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SECTION 13

Tin and Lead

M. BAUDLER

Tin Sn

TIN POWDER

S o m e w h a t b e l o w its m e l t i n g p o i n t (232°C) tin b e c o m e s b r i t t l e , s o t h a t it c a n be b r o k e n down to a p o w d e r . A p o l y m o r p h i c y- m o d i f i c a ­ t i o n , to w h i c h t h i s p r o p e r t y w a s f o r m e r l y a s c r i b e d , is not p r e s e n t a c c o r d i n g to r e c e n t x - r a y s t u d i e s .

P o w d e r e d tin c a n b e c o m m e r c i a l l y o b t a i n e d in v a r i o u s g r a d e s of f i n e n e s s . To p r e p a r e s m a l l e r q u a n t i t i e s in t h e l a b o r a t o r y , p u r e tin i s m e l t e d in a p o r c e l a i n d i s h and h e a t i n g i s c o n t i n u e d until t h e m a s s g l o w s d a r k r e d . L i q u i d t i n i s p o u r e d off f r o m t h e s u r f a c e o x i d e s c u m into a p r e h e a t e d p o r c e l a i n m o r t a r and i s v i g o r o u s l y p o u n d e d i m m e d i a t e l y a f t e r h a r d e n i n g . Since t h e m e t a l c o o l s down q u i c k l y to t e m p e r a t u r e s at which b r i t t l e n e s s d i s a p p e a r s , t h e m o r t a r s h o u l d be k e p t at about 200°C. If t h i s i s not d o n e , t h e l a r g e r u n b r o k e n p i e c e s m u s t b e h e a t t r e a t e d a g a i n .

B e c a u s e of i t s high r e a c t i v i t y , tin p o w d e r i s u s e d in p l a c e of g r a n u l a t e d tin o r tin b a r s for t h e p r e p a r a t i o n of v a r i o u s Sn c o m p o u n d s .

REFERENCES:

L . Vanin, Handb. d. p r a p . C h e m . , 3 r d E d , , Vol. I, S t u t t g a r t , 1925.

p . 587.

C. L . M a n t e l l . T i n , 2nd E d . , N e w Y o r k , 1949.

G R A Y a -TIN

C o m m o n , t e t r a g o n a l β - S n c o n v e r t s into p o w d e r y , g r a y α-Sn on i n t e n s e cooling to b e l o w 13.2°C, p a r t i c u l a r l y in t h e p r e s e n c e of s u i t a b l e c a t a l y s t s .

7 2 7

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Tin filings a r e m i x e d with a 10% s o l u t i o n of ( N H4)3 S n C l6 in a b s o l u t e alcohol in a c l o s e d flask and, when p o s s i b l e , s o m e a - S n (about 1/100 of the Sn c h a r g e ) i s added. C o m p l e t e c o n v e r s i o n to g r a y α-Sn o c c u r s on s t a n d i n g for s e v e r a l d a y s in a r e f r i g e r a t o r at — 5°C. The r e c o v e r e d p o w d e r i s c a r e f u l l y w a s h e d with cold, d i l u t e h y d r o c h l o r i c a c i d , t h e n with alcohol and e t h e r , and d r i e d in a v a c u u m d e s i c c a t o r at low t e m p e r a t u r e s .

REFERENCES:

E. Cohen and C. van Eijk. Z. p h y s i k . C h e m . 30, 601 (1899).

E . Cohen. Z. p h y s i k . C h e m . 3 5 , 588 (1900).

Tin (II) Chlorid e SnCl2

A n h y d r o u s tin (II) c h l o r i d e i s o b t a i n e d by d e h y d r a t i o n of t h e d i h y d r a t e :

SnCl2 · 2 H20 + 2 (CH3CO)20 = SnCl2 + 4 CH3COOH

225.7 204.2 189.6

C o m m e r c i a l , c r y s t a l l i z e d S n C l3 · 2 HsO (226 g.) is added with s t i r r i n g to 204 g. of a c e t i c a n h y d r i d e (99-100%) in a 6 0 0 - m l . b e a k e r . T h e d e h y d r a t i o n s t a r t s i n s t a n t a n e o u s l y with i n t e n s e h e a t evolution and t h e ( C H3C O )gO o c c a s i o n a l l y r e a c h e s boiling (use a h o o d ) ; t h e a n h y d r o u s s a l t s e p a r a t e s out in fine, white c r y s t a l s at t h e s a m e t i m e . After 1.5 h o u r s of t h i s t r e a t m e n t it i s f i l t e r e d to d r y n e s s u n d e r s u c t i o n , w a s h e d with two 1 5 - m l . p o r t i o n s of d r y e t h e r , and d r i e d in a v a c u u m d e s i c c a t o r . T h e yield i s q u a n t i t a t i v e (189 g.). T h e p r o d u c t c a n b e f u r t h e r p u r i f i e d by high v a c u u m d i s t i l l a t i o n in a V y c o r c o n t a i n e r o r , p r e f e r a b l y , in o n e of q u a r t z .

S t o r e in tightly c l o s e d g r o u n d g l a s s b o t t l e s .

PROPERTIES:

White c r y s t a l l i n e s u b s t a n c e with an oily s h e e n ; r e l a t i v e l y s t a b l e in a i r ; p a r t i a l d e c o m p o s i t i o n with h y d r o l y s i s and oxidation on c o n t i n u e d e x p o s u r e .

M.p. 247°C; t h e m e l t t e n d s to s u p e r c o o l . B . p . 606°C; d 3.95.

R h o m b i c c r y s t a l s .

R e a d i l y s o l u b l e in w a t e r ; t h e d i h y d r a t e c r y s t a l l i z e s f r o m c o n ­ c e n t r a t e d solution; at g r e a t e r d i l u t i o n s , h y d r o l y z e s with f o r m a t i o n of Sn(OH)Cl; q u i t e s o l u b l e in a c e t o n e , a m y l a l c o h o l , ethyl a c e t a t e , and a b s o l u t e m e t h a n o l and e t h a n o l .

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1 3 . T I N A N D L E A D 729

REFERENCES:

T h e a p p a r a t u s shown in F i g . 236 i s u s e d , w i t h v e s s e l s i z e c h o s e n a c c o r d i n g to t h e a m o u n t of SnCl 4 d e s i r e d . T h e P y r e x r e a c t i o n v e s s e l a i s c o n n e c t e d t h r o u g h t h e o v e r f l o w t u b e e to t h e c l o s e d r e c e i v e r o. T h e d i a m e t e r of t u b e e m u s t b e l a r g e enough s o t h a t t h e liquid o v e r f l o w i n g f r o m a d o e s not block t h e e s c a p e of g a s f r o m ο into d. Tube d i s d i r e c t l y c o n n e c t e d (via a CaCl 2 d r y i n g tube) to t h e s t a c k p a r t of t h e hood a r r a n g e m e n t . F l a s k b s e r v e s a s a s a f e t y t r a p in c a s e of liquid b a c k u p . V e s s e l α i s filled with p u r e Sn g r a n u l e s to a h e i g h t of 1-2 c m . b e l o w t h e b r a n c h i n g - o f f p o i n t of e. If p o s s i b l e , a few m i l l i l i t e r s of S n C l4 a r e a d d e d (to f a c i l i t a t e i n i t i a t i o n of t h e r e a c t i o n ) s o t h a t t h e g a s inlet t u b e / j u s t b a r e l y d i p s b e l o w t h e s u r f a c e of t h e l i q u i d . A fast s t r e a m of p u r e , d r y CI s

(see p . 272) i s i n t r o d u c e d t h r o u g h t u b e g. I m m e d i a t e l y following t h e s t a r t of t h e r e a c t i o n , a i s c o o l e d by i m m e r s i o n in w a t e r and t h e C l2 s t r e a m i s s o r e g u l a t e d t h a t t h e SnCl 4 f o r m e d d o e s not b o i l . An o c c a s i o n a l glowing of t h e Sn b e n e a t h t h e liquid c a u s e s no h a r m . T h e v e s s e l a fills r a p i d l y with S n C l4, which t h e n o v e r f l o w s into o. The

Tin (IV) Chlorid e SnCl4

I. Sn + 2 Cl2 = SnCI4

118.7 141.8 260.5

c

F i g . 2 3 6 . P r e p a r a t i o n of t i n (IV) c h l o r i d e .

O r g a n i c S y n t h e s e s , Vol. 2 3 , N e w Y o r k , 1943, p . 6 3 . H. Stephen. J . C h e m . Soc. (London) 1930, 2786.

W. F i s c h e r and R. G e w e h r . Z . a n o r g . a l l g . C h e m . 242, 188 (1939).

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y i e l d i s a l m o s t q u a n t i t a t i v e . S e v e r a l k i l o g r a m s of SnCl 4 c a n t h u s b e e a s i l y p r e p a r e d within a d a y . T h e c r u d e p r o d u c t f r o m c and α i s left s t a n d i n g for s o m e t i m e o v e r Sn foil (with o c c a s i o n a l shaking) to r e m o v e t h e d i s s o l v e d C l2. T h e c r u d e is t h e n s e p a r a t e d f r o m e x c e s s m e t a l by d i s t i l l a t i o n in a g r o u n d g l a s s a p p a r a t u s , with c a r e f u l e x c l u s i o n of m o i s t u r e ; t h e boiling p o i n t of t h e p u r e s u b ­ s t a n c e i s 114°C.

Π. SnCl4 · 5 H20 + 5 SOCl2 = SnCl4 + 5 SO, + 10 HC1

350.6 594.9 260.5 320.3 364.7

S o m e w h a t m o r e than t h e t h e o r e t i c a l l y n e c e s s a r y a m o u n t of S O C l2 ( s e e p . 382) is p o u r e d o v e r c r y s t a l l i z e d S n C l4 · 5 H20 in a flask with g r o u n d g l a s s j o i n t s and t h e m i x t u r e i s r e f l u x e d for a few h o u r s , with a d r y i n g t u b e a t t a c h e d to t h e c o n d e n s e r . After t h e r e a c t i o n , m o s t of t h e u n c o n v e r t e d S O C l2 i s d i s t i l l e d off on a w a t e r b a t h , u s i n g t h e a p p r o p r i a t e g r o u n d g l a s s a t t a c h m e n t . T h e l a s t t r a c e s of S O C l2, a s well a s of d i s s o l v e d S 02 and HC1, a r e r e m o v e d by r e p e a t e d e v a c u a t i o n of t h e r e a c t i o n flask at r o o m t e m p e r a t u r e . T h e c r u d e p r o d u c t i s p u r i f i e d by c a r e f u l f r a c t i o n a t i o n in a c o l u m n , while p r e v e n t i n g a c c e s s of m o i s t u r e . T h e c o m p l e t e l y c o l o r l e s s m i d d l e f r a c t i o n , boiling at 114°C, i s c o l l e c t e d .

PROPERTIES:

C o l o r l e s s liquid, fuming in a i r ; t a k e s up m o i s t u r e , f o r m i n g v a r i o u s h y d r a t e s and t h e r e f o r e is s t a b l e only when k e p t in h e r m e t i ­ c a l l y c l o s e d v e s s e l s .

M.p. - 3 0 . 2 ° C , b . p . +114°C; d. (20°C) 2 . 2 3 .

D i s s o l v e s e x o t h e r m i c a l l y in w a t e r with e x t e n s i v e h y d r o l y s i s to c o l l o i d a l s t a n n i c acid; m i s c i b l e in all p r o p o r t i o n s with CS 2.

REFERENCES:

I. H. D a n n e e l , Angew. C h e m . 39, 1553 (1926); s e e a l s o R. L o r e n z , Z. a n o r g . C h e m . 10, 44 (1895).

II. H. Hecht, Z. a n o r g . C h e m . 254, 37 (1947).

Hexachlorostanni c Aci d

H2S n C lE- 6 H20

SnCl4 + 2 HC1 + 6 H20 = H2SnCl6 · 6 H20

260.5 72.9 108.1 441.6

T h e s t o i c h i o m e t r i c q u a n t i t y of Η 20 ; in t h e f o r m of c o n c e n t r a t e d h y d r o c h l o r i c a c i d (66.1 g . , d 1.19) i s added to 100 g. of p u r e S n C l4 (see p r e v i o u s s e c t i o n ) . C o n s i d e r a b l e h e a t and HC1 evolution a c c o m ­ p a n y t h e r e a c t i o n . When t h e r e a c t i o n s u b s i d e s , t h e flask i s c l o s e d

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1 3 . T I N A N D L E A D 7 3 1

with a t w o - h o l e r u b b e r s t o p p e r with g a s i n l e t and o u t l e t t u b e s , both of which r e a c h to the b o t t o m of t h e flask. P u r e , d r y HC1 ( s e e p . 280) is i n t r o d u c e d at r o o m t e m p e r a t u r e . A b s o r p t i o n of t h e g a s is f a v o r e d by g e n t l e r o t a t i o n of t h e flask. At s a t u r a t i o n (weight i n c r e a s e of about 8 g . ) , t h e g a s flow i s s t o p p e d and t h e r e a c t i o n m i x t u r e is c o o l e d by p l a c i n g t h e flask in cold w a t e r . C r y s t a l s begin to s e t t l e out a f t e r a s h o r t t i m e , and s o o n t h e e n t i r e c o n t e n t s of t h e flask solidify to a flaky, c o l o r l e s s m a s s . If p u r e m a t e r i a l s h a v e b e e n u s e d a s r e a c t a n t s , t h e p r o d u c t i s q u i t e p u r e at t h i s s t a t e . It c a n b e s e p a r a t e d into f r a c t i o n s of v a r i o u s g r a d e s of p u r i t y by r e p e a t e d m e l t i n g , p a r t i a l c r y s t a l l i z a t i o n and d e c a n t a t i o n of t h e m o t h e r l i q u o r . T h e y i e l d i s a l m o s t q u a n t i t a t i v e .

R e m a i n s s t a b l e only when s t o r e d in s e a l e d a m p o u l e s .

PROPERTIES:

C o l o r l e s s , flaky c r y s t a l s ; v e r y d e l i q u e s c e n t in m o i s t a i r with s i m u l t a n e o u s l i b e r a t i o n of HC1 and f o r m a t i o n of S n C l4 · 5 H20 .

M . p . 19.2°C; g i v e s off HC1 at s o m e w h a t h i g h e r t e m p e r a t u r e s ; d (27-28°C) 1.925.

REFERENCE:

K. S e u b e r t . B e r . d t s c h . c h e m . G e s . 2 0 , 793 (1887).

Ammoniu m Hexachlorostannate ; Potassiu m Hexachlorostannat e

(NH4)2SnCle; K2SnCle SnCl4 + 2 NH4C1 = (NH4)2SnCl6

260.5 107.0 367.5

SnCl4 + 2 KC1 = K2SnCl6

260.5 149,1 409.6

P u r e , a n h y d r o u s S n C l4 ( s e e p . 729) i s d i s s o l v e d in an e q u a l weight of H20 and i s d e c o m p o s e d with a 50% e x c e s s of s a t u r a t e d M(I)C1 s o l u t i o n . White c r y s t a l s of M ( I )sS n C l6 s e p a r a t e out on c o o l i n g . If d e s i r e d , t h e v o l u m e of s o l u t i o n c a n b e s o m e w h a t r e d u c e d b e f o r e h a n d by e v a p o r a t i o n . To c o m p l e t e t h e c r y s t a l l i z a t i o n , t h e s o l u t i o n i s a l l o w e d to s t a n d for s o m e t i m e in i c e and t h e c r y s t a l s a r e t h e n s u c k e d d r y w h i l e c o l d . T h e y a r e w a s h e d w i t h s o m e i c e w a t e r and d r i e d on c l a y in a d e s i c c a t o r . A c o n c e n t r a t e d s o l u t i o n of S n C l4- 5 H20 , c o n t a i n i n g s o m e h y d r o c h l o r i c a c i d , m a y a l s o b e u s e d in t h i s r e a c t i o n .

SYNONYM:

T h e a m m o n i u m s a l t ( N H4)2S n C l6, i s known in i n d u s t r y a s

"pink s a l t . " It i s u s e d a s a m o r d a n t in dyeing.

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PROPERTIES:

White, c r y s t a l l i n e s u b s t a n c e s , m a y b e s t o r e d in a i r . Both m a t e r i a l s a r e v e r y s o l u b l e in w a t e r ; boiling c a u s e s p r e c i p i t a t i o n of S n 02 · η H20 f r o m d i l u t e s o l u t i o n s .

( N H4)2S n C l6: d 2.39 K g S n C l e : d 2.71

C r y s t a l s h a v e a J Ι χ - t y p e s t r u c t u r e ( K3P t C l6) .

REFERENCES:

H. F . W a l t o n . I n o r g a n i c P r e p a r a t i o n s , N e w Y o r k , 1948, p . 110.

R. G. D i c k i n s o n . J . A m e r . C h e m . Soc. 4 4 , 276 (1922).

B o l l e y . L i e b i g s Ann. C h e m . 3 9 , 100 (1841).

Tin (II) Bromid e SnBr2

T h i s c o m p o u n d i s p r e p a r e d by d i s s o l v i n g Sn in c o n c e n t r a t e d h y d r o b r o m i c a c i d and c o n c e n t r a t i n g t h i s s o l u t i o n , t h u s f o r m i n g H20 - a n d H B r - c o n t a i n i n g c r y s t a l s of S n B r2. P u r e S n B r2i s f o r m e d on f u r t h e r h e a t i n g .

C o n c e n t r a t e d h y d r o b r o m i c a c i d i s p o u r e d o v e r Sn p o w d e r ( s e e p . 727) c o n t a i n e d in a f l a s k , and t h e l a t t e r i s w a r m e d on a s a n d b a t h until t h e i n i t i a l v i g o r o u s h y d r o g e n e v o l u t i o n s l o w s down. T h e

liquid i s t h e n d e c a n t e d f r o m t h e u n d i s s o l v e d Sn and e v a p o r a t e d on a w a t e r b a t h in t h e p r e s e n c e of s o m e Sn foil until a s a l t s c u m f o r m s on t h e s u r f a c e . N e e d l e - s h a p e d c r y s t a l s s e p a r a t e out on cooling.

T h e s e a r e q u i c k l y s u c k e d d r y t h r o u g h a f r i t t e d g l a s s f i l t e r and a r e p l a c e d in a v a c u u m o v e r H2S 04, w h e r e t h e y a r e s u r f a c e - d r i e d for a

s h o r t t i m e on c l a y . While s t i l l m o i s t , t h e c r y s t a l s a r e p u t into a r o u n d - b o t t o m e d P y r e x f l a s k and h e a t e d in a s t r e a m of p u r e N3. An o p e n f l a m e i s u s e d . T h e f l a s k i s at f i r s t fanned c a r e f u l l y , t h e n t h e f l a m e i s a p p l i e d s o m e w h a t m o r e d i r e c t l y . T h e w a t e r and t h e H B r a d h e r i n g t o t h e c r y s t a l s c o m e o v e r f i r s t . With c o n t i n u e d i n c r e a s e in t e m p e r a t u r e , l a r g e r a m o u n t s of H B r a r e l i b e r a t e d b e c a u s e of d e c o m p o s i t i o n of t h e i n t e r m e d i a t e c o m p o u n d s p r e s e n t . H e a t i n g i s c o n t i n u e d until no f u r t h e r g a s b u b b l e s a r e p r o d u c e d and a c l e a r m e l t of S n B r2 i s f o r m e d . After cooling in a s t r e a m of Ν 2, t h e p r o d u c t m a y b e p u r i f i e d by d i s t i l l a t i o n in a q u a r t z a p p a r a t u s ( u n d e r a n i t r o g e n b l a n k e t ) . B . p . (1 a t m . ) in a weak s t r e a m of N3: 618°C,

PROPERTIES:

F o r m u l a weight 2 7 8 . 5 3 . B r i g h t yellow, c r y s t a l l i n e s u b s t a n c e ; s o m e w h a t h y g r o s c o p i c and s e n s i t i v e to light.

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1 3 . T I N A N D L E A D 733 M . p . 232°C, b . p . 618°C; p a r t i a l l y o x i d i z e d to Sn (IV) c o m p o u n d s on h e a t i n g in a i r ; d 4.92.

H y d r o l y z e d b y w a t e r but s o l u b l e without c h a n g e i n p y r i d i n e .

REFERENCES:

F . F r e y e r and V. M e y e r . Z. a n o r g . C h e m . 2 , 1 (1892).

G. Wittig and H. H a r t m a n n . B e r . d t s c h . c h e m . G e s . 72, 1387 (1939).

J . K e n d a l l , E. D. C r i t t e n d e n and Η. K. M i l l e r . J . A m e r . C h e m . Soc. 4 5 , 963 (1923).

Tin (IV) Bromid e SnBr4

Sn + 2 B r2 = SnBr4

118.7 319.7 438.4

T h e r e a c t i o n i s c a r r i e d out in a d i s t i l l i n g flask with a long n e c k , t h e s i d e a r m of which i s a t t a c h e d a s c l o s e to t h e body of t h e flask a s p o s s i b l e and e n d s in a C a C l2 d r y i n g t u b e . P i e c e s of Sn, 2 - 3 c m . long, a r e p l a c e d in t h e f l a s k , which i s t h e n c l o s e d above with a s i n g l e - h o l e r u b b e r s t o p p e r . A d r o p p i n g funnel, with i t s t u b e d r a w n out to a c a p i l l a r y , i s i n s e r t e d in s u c h a way t h a t t h e t u b e e n d s in t h e l o w e s t p a r t of t h e n e c k of the flask but d o e s not p e n e t r a t e into t h e body of t h e f l a s k . P u r e B r2 ( s e e p . 275) i s c a r e f u l l y a d d e d d r o p w i s e ; t h i s i n s t a n t l y p r o d u c e s a v i g o r o u s r e a c t i o n , a c c o m p a n i e d by a l a r g e h e a t evolution a n d p o s s i b l e ignition. F u r t h e r a d d i t i o n of B r2 m u s t b e s o r e g u l a t e d t h a t t h e r e a c t i o n t e m p e r a t u r e s t a y s b e l o w 59°C (b.p. of B r2) and no S n B r4 o r B r 2 p e n e t r a t e s into t h e s i d e a r m . When m o s t of t h e t i n i s c o n s u m e d and a sufficient a m o u n t of liquid c o l l e c t s on t h e b o t t o m of t h e flask, t h e d r o p p i n g funnel i s r e p l a c e d by a t h e r m o m e t e r and t h e flask i s m a n i p u l a t e d s o t h a t t h e s i d e a r m p o i n t s d i r e c t l y u p w a r d s . E x c e s s B r2 i s r e m o v e d b y boiling for a few m i n u t e s , d u r i n g which t i m e t h e S n B r 4 c o n d e n s e s and r u n s b a c k into t h e f l a s k . When t h e p r o d u c t b e c o m e s n e a r l y c o l o r l e s s , t h e flask i s r e s t o r e d to n o r m a l p o s i t i o n and t h e m a t e r i a l is d i s t i l l e d into an a t t a c h e d r e c e i v i n g v e s s e l , t a k i n g c a r e to k e e p a t m o s p h e r i c m o i s t u r e out. F r e e z i n g of t h e SnBr 4 to a s n o w - w h i t e c r y s t a l l i n e m a s s i s a c c o m p a n i e d by a s m a l l i n c r e a s e in v o l u m e (caution, t h i n - w a l l e d r e c e i v e r s m a y b u r s t ) . F o r f u r t h e r p u r i f i c a t i o n , t h e c r u d e p r o d u c t m a y b e r e m e l t e d , p a r t i a l l y s o l i d i f i e d and t h e liquid p o u r e d off and d i s c a r d e d . A l t e r n a t e l y , t h e l a s t s t e p m a y b e r e p l a c e d by f r a c t i o n a l d i s t i l l a t i o n in a g r o u n d g l a s s a p p a r a t u s .

To p r e s e r v e for e x t e n d e d p e r i o d s of t i m e , m u s t b e s t o r e d in s e a l e d a m p o u l e s o r in g r o u n d g l a s s b o t t l e s with t i g h t l y fitting s t o p p e r s .

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S Y N O N Y M :

Tin t e t r a b r o m i d e , s t a n n i c b r o m i d e .

P R O P E R T I E S:

W h i t e , c r y s t a l l i n e s u b s t a n c e s ; f u m e s s o m e w h a t in d a m p a i r ; h y g r o s c o p i c .

M.p. 33°C, b . p . 201°C; s u b l i m e s r e a d i l y in a s e a l e d t u b e ; s t a b l e e v e n on s t r o n g h e a t i n g ; d (35°C) 3.35.

D i s s o l v e s in w a t e r with c o m p l e t e h y d r o l y s i s ; s o l u b l e without c h a n g e in A s B r3.

R h o m b i c c r y s t a l s , Dsh

R E F E R E N C E:

R. L o r e n z . Z. a n o r g . a l l g . C h e m . 9, 365 (1895).

Tin (II) Iodid e Snl2

Sn + 2 HI = Snl2 + H2

118.7 255,9 372.5 2.0

P u r e tin i s c o v e r e d with an e x c e s s of c o n c e n t r a t e d h y d r i o d i c a c i d in a flask with g r o u n d j o i n t s . A r e f l u x c o n d e n s e r i s t h e n a t t a c h e d and t h e flask c o n t e n t s b o i l e d until t h e m e t a l d i s s o l v e s and r e d c r y s t a l s of S n l3 begin to s e p a r a t e out. The c o p i o u s p r o d u c t which p r e c i p i t a t e s on cooling is s u c k e d t h r o u g h a f r i t t e d g l a s s f i l t e r c r u c i b l e and r e c r y s t a l l i z e d f r o m a l c o h o l . T h e c r y s t a l s a r e finally d r i e d in a v a c u u m d e s i c c a t o r o v e r P205. F o r a v e r y p u r e p r e p a r a ­ tion t h e m a t e r i a l c a n be r e p u r i f i e d by h i g h - v a c u u m d i s t i l l a t i o n in a q u a r t z a p p a r a t u s .

II. SnCl2 + 2 KI = Snl2 + 2 KC1

(2 H20 )

225.7 332.0 372.5

An a g i t a t e d , m o d e r a t e l y c o n c e n t r a t e d a q u e o u s s o l u t i o n of SnCl 8 i s r a p i d l y m i x e d with a KI s o l u t i o n of about t h e s a m e c o n c e n t r a t i o n c o n t a i n i n g half the s t o i c h i o m e t r i c a m o u n t of KI. If a l a r g e r q u a n t i t y of KI i s added, a y e l l o w double s a l t c o p r e c i p i t a t e s with t h e r e d S n l2 and i s difficult to s e p a r a t e . After f i l t e r i n g t h e S n l3, a d d i t i o n a l p r o d u c t m a y b e o b t a i n e d f r o m t h e m o t h e r l i q u o r b y addition of t h e s e c o n d half of t h e s t o i c h i o m e t r i c a m o u n t of KI. T h i s m e t h o d y i e l d s a p r e p a r a t i o n which, in g e n e r a l , i s l e s s p u r e t h a n t h a t o b t a i n e d via m e t h o d I. P u r i f i c a t i o n and d r y i n g of the p r o d u c t a r e a s in I.

I.

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1 3 . T I N A N D L E A D 735

SYNONYM:

Stannous i o d i d e .

PROPERTIES:

R e d , c r y s t a l l i n e s u b s t a n c e . M.p. 320°C, b . p . 720°C; d 5 . 2 8 . S o m e w h a t s o l u b l e in w a t e r (100 g. of s o l u t i o n c o n t a i n s 0.96 g. of S n l2 at 19.8°C, 1.72 g. at 49.5°C, 3.70 g. a t 97.3°C); a l s o s o l u b l e in w a r m C H C 13, C Sa and C6H6.

R h o m b i c c r y s t a l s .

REFERENCES:

I. W. R e i n d e r s and S. de L a n g e . Z. a n o r g . a l l g . C h e m . 79, 230 (1913); W. F i s c h e r and R. G e w e h r . Z. a n o r g . a l l g . C h e m . 242, 188 (1939).

II. B, Kohnlein. L i e b i g s Ann. C h e m . 2 2 5 , 171 (1884); G. W a g n e r . A n o r g a n i s c h - p r a p a r a t i v e s P r a k t i k u m , Vienna, 1947, p . 85.

Tin (IV) Iodid e Snl4

S n 4- 2 I2 = S n l4 118.7 507,7 626.4

Six p a r t s by w e i g h t of v e r y p u r e C S3a r e p o u r e d o v e r o n e p a r t by weight of S n p o w d e r in a r o u n d flask with a g r o u n d g l a s s s t o p p e r , and four p a r t s by w e i g h t of I2 a r e g r a d u a l l y a d d e d . T h e s t o p p e r m u s t b e i n s e r t e d e x c e p t d u r i n g a c t u a l addition. If l a r g e a m o u n t s of r e a c t i o n s a r e u s e d , the flask m u s t b e c o o l e d with i c e . The r e d - b r o w n s o l u t i o n f o r m e d i s t h e n d r a w n off f r o m t h e e x c e s s of Sn (keep m o i s t u r e out) and e v a p o r a t e d to d r y n e s s u s i n g an a s p i r a t o r v a c u u m . W a t e r v a p o r f r o m t h e a s p i r a t o r m u s t be p r e v e n t e d f r o m r e a c h i n g t h e p r o d u c t . The r e d S n l4 o b t a i n e d is a n a l y t i c a l l y p u r e .

SYNONYM:

T i n t e t r a i o d i d e , s t a n n i c i o d i d e .

PROPERTIES:

O r a n g e - r e d , n e e d l e - s h a p e d c r y s t a l s . M o i s t u r e s e n s i t i v e , h y d r o - l y z e c o m p l e t e l y in w a t e r ; s o l u b l e without c h a n g e i n C S2, C H C 13 and

C H g I2. M.p. 143.5°C, b . p . 340°C, d 4 . 4 6 . C r y s t a l s : D l l s t r u c t u r e t y p e .

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REFERENCES:

R. S c h n e i d e r . P o g g . Ann. 127, 624.

H. H e c h t . P r a p a r a t i v e a n o r g a n i s c h e C h e m i e , B e r l i n - G o t t i n g e n - H e i d e l b e r g , 1 9 5 1 , p . 102.

Tin (II) Oxid e SnO

The p r e p a r a t i o n i n v o l v e s c o n v e r s i o n of t i n (II) c h l o r i d e to h y d r a t e d tin (II) o x i d e , which i s t h e n d e h y d r a t e d to SnO by e x t e n d e d h e a t i n g in an a q u e o u s s o l u t i o n .

A s o l u t i o n of C P . S n C l2 · 2 H20 i s p r e p a r e d in t h e s m a l l e s t p o s s i b l e q u a n t i t y of hot c o n c e n t r a t e d h y d r o c h l o r i c a c i d , and a N a2C 03 s o l u t i o n i s a d d e d until t h e m i x t u r e g i v e s an a l k a l i n e r e a c t i o n with p h e n o l p h t h a l e i n p a p e r (not l i t m u s p a p e r , s i n c e t h e l a t t e r g i v e s a r e a c t i o n at too s m a l l an e x c e s s of a l k a l i ) . T h e N a20 O3 s o l u t i o n m u s t b e added c a r e f u l l y and g r a d u a l l y s i n c e the m i x t u r e f o a m s o v e r q u i t e r e a d i l y . The white h y d r a t e d Sn (II) oxide which s e t t l e s out i s h e a t e d for 2 - 3 h o u r s in t h e s u p e r n a t a n t liquid (bath l i q u i d : s a t u r a t e d s o l u t i o n of N a C l , b . p . 110°C), t h u s c a u s i n g q u a n t i t a t i v e c o n v e r s i o n t o b l u e - b l a c k , m e t a l l i c a l l y l u s t r o u s SnO. T h e p r o d u c t i s p u r i f i e d by w a s h i n g s e v e r a l t i m e s with d i s t i l l e d w a t e r and d r i e d at 110°C.

Y i e l d : about 80%.

P u r e SnO s h o u l d yield a c l e a r s o l u t i o n with h y d r o c h l o r i c a c i d , but a v e r y s l i g h t o p a l e s c e n c e i s a c c e p t a b l e .

SYNONYM:

Stannous o x i d e .

PROPERTIES:

F o r m u l a w e i g h t 134.70. B l u e - b l a c k , c r y s t a l l i n e s u b s t a n c e w i t h m e t a l l i c s h e e n . In a i r , i s o x i d i z e d to S n 02 a b o v e 220°C; in i n e r t g a s , d e c o m p o s e s to Sn and S n304 at ~ 4 0 0 ° C . An SnO m e l t i s s t a b l e

and h a r d e n s (with s i m u l t a n e o u s d i s p r o p o r t i o n a t i o n into Sn and S n304) at 1040°C. Above 1000°C, SnO a t t a c k s s i l i c a t e - c o n t a i n i n g m a t e r i a l s , f o r m i n g Sn (II) s i l i c a t e ; v e s s e l s m a d e of s i n t e r e d c o r u n d u m m a y b e u s e d up to 1600°C. B.p. ( e s t i m a t e d ) 1700°C, d 6.32.

I n s o l u b l e in w a t e r ; s o l u b l e in a c i d s , y i e l d i n g Sn (II) s a l t s . C r y s t a l s : Β 10 s t r u c t u r e t y p e .

REFERENCES:

W. F r a e n k e l and K. S n i p i s c h s k i . Z. a n o r g . a l l g , C h e m . 125, 235 (1922).

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1 3 . T I N A N D L E A D 737 M. S t r a u m a n i s and C. S t r e n k . Z. a n o r g . a l l g . C h e m . 2 1 3 , 301

(1933).

C. G. F i n k and C. L. M a n t e l l . J . P h y s . C h e m . 3 2 , 103 (1928).

H. S p a n d a u a n d E . J . K o h l m e y e r . Z. a n o r g . C h e m . 254, 65 (1947).

Stanni c Acid s

S n 02n H20 a-STANNIC ACID

I. PREPARATION BY HYDROLYSIS OF AN S n ( S 04)2 SOLUTION

V e r y p u r e t i n (30 g.) i s d i s s o l v e d in 20 m l . of b o i l i n g c o n c e n t r a t e d

Η2^ 04 (at 1.84) and t h e s o l u t i o n i s k e p t b o i l i n g until t h e s e p a r a t e d s u l f u r a g g l o m e r a t e s and t h e liquid c l e a r s . A f t e r c o o l i n g , t h e m i x t u r e i s f i l t e r e d t h r o u g h a f r i t t e d g l a s s f i l t e r c r u c i b l e . C o n c e n t r a t e d H2S 04 i s a g a i n a d d e d to t h e f i l t r a t e to m a k e t h e t o t a l v o l u m e 200 m l . F o r t h e h y d r o l y s i s t h e S n ( S 04)2 s o l u t i o n i s r a p i d l y and d r o p w i s e a d d e d to o n e l i t e r of d i s t i l l e d w a t e r (good a g i t a t i o n i s n e c e s s a r y ) . T h e t e m p e r a t u r e of t h e w a t e r i s m a i n t a i n e d at 0-2°C by e x t e r n a l c o o l i n g . A s l i g h t l y o p a l e s c e n t liquid i s f o r m e d . T h i s i s d i l u t e d t h e n e x t d a y with 5 l i t e r s of i c e - c o l d d i s t i l l e d w a t e r . Milky w h i t e α - s t a n n i c a c i d s e p a r a t e s out. It i s a l l o w e d to s e t t l e for a s h o r t t i m e , and m o s t of t h e s u l f u r i c a c i d i s r e m o v e d b y w a s h i n g t h e p r e c i p i t a t e w i t h s u c c e s s i v e l y l a r g e r a m o u n t s of d i s t i l l e d w a t e r . T h i s i s c o n t i n u e d until t h e w a s h w a t e r g i v e s an a l m o s t n e u t r a l r e a c t i o n to l i t m u s . T h e p r e c i p i t a t e i s t h e n t r a n s f e r r e d to a leaf f i l t e r and t h e w a s h i n g i s c o n t i n u e d by r e p e a t e d r e s u s p e n s i o n in w a t e r and f i l t r a t i o n . C o m p l e t e r e m o v a l of t h e a d s o r b e d s u l f u r i c a c i d (negative B a C l 2 r e a c t i o n in t h e w a s h w a t e r ) i s u s u a l l y a t t a i n e d o n l y a f t e r a f o u r - w e e k t r e a t m e n t . The α - s t a n n i c a c i d c a n b e d r i e d in a i r at r o o m t e m p e r a t u r e a n d t h e n g r o u n d t o p o w d e r . H o w e v e r , it p a r t i a l l y c o n v e r t s to t h e / ? - f o r m d u r i n g t h i s o p e r a t i o n .

II. REACTION OF AN M e ( I )s Sn(OH)e SOLUTION WITH ACID

An a g i t a t e d s o l u t i o n of N asS n ( O H )6 (see s e c t i o n on h y d r o x y s a l t s ) i s s l o w l y a l l o w e d to r e a c t with d i l u t e h y d r o c h l o r i c a c i d a t r o o m t e m p e r a t u r e until t h e m i x t u r e i s a l m o s t n e u t r a l . The c o p i o u s α - s t a n n i c a c i d p r e c i p i t a t e s e t t l i n g out i s t r e a t e d a s in m e t h o d I.

C o m p l e t e r e m o v a l of a d s o r b e d f o r e i g n i o n s , p a r t i c u l a r l y N a+, p r e s e n t s g r e a t e r difficulty h e r e t h a n in m e t h o d I, w h e r e no a l k a l i i s u s e d .

III. REACTION OF AN S n C i4 SOLUTION WITH AMMONIA

A s m a l l e x c e s s of a m m o n i a i s a d d e d to an a q u e o u s s o l u t i o n of S n C l4« 5 H20 , w h i c h m a y b e c l e a r e d b y a d d i n g a few d r o p s of c o n c e n t r a t e d h y d r o c h l o r i c a c i d . T h e g e l a t i n o u s w h i t e p r e c i p i t a t e

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of α - s t a n n i c a c i d i s p u r i f i e d a s in m e t h o d I. H o w e v e r , t h e c o m p l e t e r e m o v a l of a d s o r b e d f o r e i g n i o n s i s e x t r e m e l y difficult.

PROPERTIES:

White, g e l a t i n o u s p r e c i p i t a t e ; after d r y i n g , a w h i t e , g l a s s y s u b s t a n c e ; i n c r e a s e d d e h y d r a t i o n and c o n v e r s i o n to α - s t a n n i c a c i d on aging; t h i s p r o c e s s is a c c e l e r a t e d by h e a t .

F r e s h l y p r e p a r e d , m o i s t α - s t a n n i c a c i d i s s o l u b l e in s u l f u r i c , h y d r o c h l o r i c and n i t r i c a c i d s a s well a s in s o d i u m h y d r o x i d e , f o r m i n g t h e c o r r e s p o n d i n g Sn (IV) s a l t s .

X - r a y a n a l y s i s s h o w s t h a t f r e s h l y p r e p a r e d α - s t a n n i c a c i d is a m o r p h o u s ; on aging, t h e m a t e r i a l i n c r e a s i n g l y s h o w s a faded p o w d e r p a t t e r n with S n Os l i n e s .

REFERENCES:

I. A. G u t b i e r , G. F . Huttig and H. Dobling. B e r . d t s c h . c h e m . G e s . 59, 1232 (1926); W. M e c k l e n b u r g . Z. a n o r g . a l l g . C h e m . 74, 207 (1912).

II. E . P o s n j a k . J. P h y s . C h e m . 30, 1073 (1926).

III. Η. B. W e i s e r and W. O. M i l l i g a n . J . P h y s . C h e m . 36, 3030 (1932).

β-STANNIC ACID

The c o m p o u n d i s p r e p a r e d by oxidation of m e t a l l i c Sn with c o n c e n t r a t e d n i t r i c a c i d .

An e x c e s s of c o n c e n t r a t e d n i t r i c a c i d (d 1.41) i s p o u r e d o v e r p u r e , g r a n u l a t e d Sn in a deep p o r c e l a i n d i s h , and t h e m i x t u r e i s h e a t e d on a w a t e r b a t h with r e p e a t e d addition of f r e s h a c i d . A f t e r c o o l i n g , m o s t of t h e n i t r i c a c i d i s d e c a n t e d . T h e p o w d e r e d p r e c i p i ­ t a t e of β - s t a n n i c a c i d i s d i g e s t e d s e v e r a l t i m e s with cold d i s t i l l e d w a t e r and w a s h e d on a f i l t e r until t h e w a s h w a t e r s h o w s no f u r t h e r r e a c t i o n with d i p h e n y l a m i n e (about 25 w a s h i n g s a r e r e q u i r e d ) . The p r o d u c t m a y b e d r i e d in a i r at r o o m t e m p e r a t u r e .

PROPERTIES:

White, m i c r o c r y s t a l l i n e p o w d e r . L o s e s w a t e r i n c r e a s i n g l y on h e a t i n g and finally c o n v e r t s to SnO 2 at r e d h e a t .

I n s o l u b l e in s u l f u r i c a c i d (as o p p o s e d to α - s t a n n i c a c i d ) , c o n ­ c e n t r a t e d h y d r o c h l o r i c and n i t r i c a c i d s , a s well a s c o n c e n t r a t e d s o d i u m h y d r o x i d e .

G i v e s t h e s a m e p o w d e r p a t t e r n a s S n Os.

REFERENCES:

A. K l e i n s c h m i d t . M o n a t s h . C h e m . 3 9 , 149 (1918).

E . P o s n j a k , J . P h y s . C h e m . 30, 1073 (1926).

Η. B. W e i s e r and W. O. M i l l i g a n . J . P h y s . C h e m . 36, 3030 (1932).

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1 3 . T I N A N D L E A D 739 Sodiu m Orthostannat e

N a4S n 04

S n 02 + 2 Na20 = Na4Sn04

150.7 124.0 274.7

Since b o t h t h e N asO s t a r t i n g m a t e r i a l and t h e N a ^ S n O ^ p r o d u c t a r e s e n s i t i v e to C 03 and m o i s t u r e in t h e a i r , t h e p r e t r e a t m e n t of s t a r t i n g m a t e r i a l s , t h e r e a c t i o n i t s e l f and t h e h a n d l i n g of the p r o d u c t m u s t c o n f o r m to c e r t a i n r u l e s . An a l l - g l a s s a p p a r a t u s i s u s e d and t h e p r e p a r a t i o n p r o c e e d s e i t h e r in a v a c u u m o r u n d e r an i n e r t g a s b l a n k e t . F o r d e t a i l s c o n c e r n i n g s u i t a b l e a p p a r a t u s and i t s h a n d l i n g , a s well a s t h e t e c h n i q u e s of w o r k i n g with e x c l u s i o n of a i r , s e e t h e q u o t e d o r i g i n a l l i t e r a t u r e and P a r t I, p . 53 ff.

P u r e SnO 3 i s d r i e d in a v a c u u m at 500°C and i s g r o u n d and t h o r o u g h l y m i x e d with t h e s t o i c h i o m e t r i c a m o u n t of N a Os in a v a c u u m b a l l m i l l ( d e s c r i b e d in P a r t I, pe 76), When t h e p o w d e r b e c o m e s s o fine t h a t it b e g i n s to a d h e r e to t h e g l a s s w a l l s , t h e g r i n d i n g i s s t o p p e d and t h e m i x t u r e i s t r a n s f e r r e d into a s i n t e r e d m a g n e s i a b o a t , e x c l u d i n g a i r a s m e n t i o n e d a b o v e . T h e b o a t , in a p r o t e c t i v e s i l v e r t u b e p l a c e d in t h e h e a t e d z o n e of a h i g h - m e l t i n g g l a s s t u b e (I.D. of 25 m m . ) , i s h e a t e d i n a v a c u u m for s o m e t i m e a t 500°C. C o m p l e t e c o n v e r s i o n to N a ^ n O , ^ t a k e s p l a c e . The h a r d p r o d u c t of t h e r e a c t i o n i s l o o s e n e d with a c h i s e l while m a i n t a i n i n g a flow of p u r i f i e d g a s a n d t h e e x a c t c o m p o s i t i o n (which v a r i e s s o m e w h a t with t h e length of h e a t i n g t i m e ) i s d e t e r m i n e d by a n a l y s i s . O c c a s i o n a l l y , t h e white s a l t i s t i n t e d g r e e n o r b r o w n by s o m e Ag f r o m t h e p r o t e c t i v e t u b e ; h o w e v e r , t h i s i m p u r i t y i s u n d e t e c t a b l e by a n a l y t i c a l o r x - r a y t e c h n i q u e s .

PROPERTIES:

White, h y g r o s c o p i c c r y s t a l l i n e s u b s t a n c e ; r e a c t s v i g o r o u s l y with w a t e r , f o r m i n g a s l i g h t l y c l o u d y s o l u t i o n , w h i c h c l e a r s on addition of o x a l i c a c i d .

REFERENCE:

E . Z i n t l and W. M o r a w i e t z . Z . a n o r g . a l l g . C h e m . 236, 372 (1938).

Tin (II) Sulfid e SnS (Crystalline )

Sn + S = SnS

118.7 32,1 150.8

T h e p r e p a r a t i o n f r o m t h e e l e m e n t s c a n n o t b e c a r r i e d out in a s i n g l e s t e p , s i n c e at t h e high t e m p e r a t u r e s u s e d a p o r t i o n of t h e

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sulfur v a p o r i z e s b e f o r e it c a n r e a c t . F o r t h i s r e a s o n an e x c e s s of S m u s t b e u s e d and t h e f i r s t r e a c t i o n p r o d u c t m u s t b e r e p e a t e d l y t r e a t e d with a d d i t i o n a l s u l f u r until t h e a p p r o x i m a t e c o m p o s i t i o n SnS is a t t a i n e d . F i n a l p u r i f i c a t i o n i s c a r r i e d out in a s t r e a m of Η 2.

A p o r c e l a i n t u b e , c l o s e d on one s i d e , i s filled with a few g r a m s of s u l f u r and h e a t e d in a f u r n a c e to about 900°C. A m i x t u r e of Sn and double t h e s t o i c h i o m e t r i c q u a n t i t y of s u l f u r i s added in p o r t i o n s to t h e t u b e , which by t h i s t i m e i s filled with S v a p o r . A s o m e w h a t n o n u n i f o r m c a k e i s f o r m e d . T h e u p p e r l a y e r c o n t a i n s l a r g e , flaky c r y s t a l s of SnS, while t h e u n d e r s i d e i s r i c h e r in Sn. After c o o l i n g , t h e p r o d u c t i s p u l v e r i z e d , m i x e d with t h e s a m e q u a n t i t y of sulfur a s b e f o r e , and r e p l a c e d in t h e h e a t e d t u b e . T h i s s e c o n d t r e a t m e n t often y i e l d s a h o m o g e n e o u s c a k e with t h e a p p r o x i m a t e c o m p o s i t i o n SnS. If t h i s i s not t h e c a s e , t h e h e a t i n g m u s t b e c o n ­ t i n u e d with o r without t h e a d d i t i o n of S, d e p e n d i n g on t h e a n a l y s i s . F o r p u r i f i c a t i o n , t h e c r u d e p r o d u c t i s t r a n s f e r r e d into an o p e n p o r c e l a i n t u b e and s u b l i m e d f r o m a b o a t in a s t r e a m of Η 2 at b r i g h t r e d h e a t . Any e x c e s s s u l f u r which m i g h t b e p r e s e n t i s d r i v e n off at l o w e r t e m p e r a t u r e s and t h e p u r e SnS v a p o r i z e s at high h e a t . It c o n d e n s e s n e a r t h e boat in beautiful s h i n y c r y s t a l s .

Π. S n 02 + 2 KSCN = SnS + K2S + 2 CO + N2

150.7 194.4 150.8 110.3 56.0 28.0

V e r y p u r e , c o m p l e t e l y a n h y d r o u s KSCN i s u s e d a s t h e s t a r t i n g m a t e r i a l . It is o b t a i n e d b y t h e r e p e a t e d r e c r y s t a l l i z a t i o n of t h e c o m m e r c i a l p r o d u c t f r o m boiling 96% ethanol and d r y i n g u n d e r v a c u u m a t l 0 0 ° C . About 10 p a r t s of t h e s a l t a r e m e l t e d in a p o r c e l a i n c r u c i b l e until t h e a p p e a r a n c e of a b l u e c o l o r (t ? » 4 5 0oC ) , and 1 p a r t of p u r e S n 02 i s t h e n g r a d u a l l y added. T h e r e a c t i o n is a c c o m p a n i e d by a v i g o r o u s evolution of g a s , and one s h o u l d wait b e f o r e e a c h n e w addition of S n Os until a c l e a r , flowing m e l t i s r e e s t a b l i s h e d . T h e t e m p e r a t u r e s h o u l d not e x c e e d t h e i n i t i a l v a l u e 450°C) to avoid c o n v e r s i o n of t h e SnS p r o d u c t to K2S n S3. When all t h e S n Os h a s b e e n a d d e d , t h e m i x t u r e i s f u r t h e r h e a t e d for 15 m i n u t e s and i s t h e n a l l o w e d to cool g r a d u a l l y . On t r e a t m e n t with w a t e r , t h e g r a y m e l t y i e l d s a r e s i d u e of c r y s t a l l i n e , a n a l y t i c a l l y p u r e SnS.

PROPERTIES:

D a r k b l u e - g r a y , c r y s t a l l i n e m a s s with a b l u i s h m e t a l l i c s h e e n . The c r y s t a l s a r e soft, f r i a b l e and g i v e a c o l o r e d s t r e a k .

M . p . 882°C; on h a r d e n i n g , t h e m e l t e x p a n d s n o t i c e a b l y b e t w e e n 400 and 600°C s o that t h i n - w a l l e d v e s s e l s m a y b u r s t . B.p. (in i n e r t g a s ) ~ 1230°C; h e a t i n g in a i r to a high t e m p e r a t u r e r e s u l t s in o x i d a t i o n to S n 02; d 5 . 0 8 .

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1 3 . T I N A N D L E A D 7 4 1

A l m o s t i n s o l u b l e in w a t e r (1.36 · 10 "6 g. in 100 g. at 18°C);

s o l u b l e (with c h e m i c a l c h a n g e ) in c o n c e n t r a t e d h y d r o c h l o r i c a c i d and y e l l o w a m m o n i u m s u l f i d e .

C r y s t a l s : Β 29 s t r u c t u r e t y p e .

REFERENCES:

I. W. B i l t z and W. M e c k l e n b u r g . Z. a n o r g . a l l g . C h e m . 64, 226 (1909); A. D i t t e . C o m p t e s R e n d u s Hebd. S e a n c e s A c a d . Sci.

96, 1790 (1883).

II. J . M i l b a u e r . Z. a n o r g . C h e m . 4 2 , 433 (1904).

Tin (IV) Sulfid e SnS2 (Crystalline )

(NH4C1)

Sn + 2S = SnS2

118.7 64.1 182.8

T h e t i n n e c e s s a r y for t h e p r e p a r a t i o n i s a d d e d in t h e f o r m of a r e a c t i v e Sn a m a l g a m . T h e l a t t e r i s p r e p a r e d b y g e n t l y h e a t i n g 6.5 p a r t s of Hg in an e v a p o r a t i n g d i s h on a s a n d b a t h (use a hood) with g r a d u a l a d d i t i o n of 13 p a r t s of Sn c h i p s . When t h e c o n v e r s i o n i s c o m p l e t e , t h e p r o d u c t i s a l l o w e d to cool and i s c o a r s e l y g r o u n d with a g l a s s r o d d i r e c t l y a f t e r s o l i d i f i c a t i o n . T h e m a s s i s t h e n f u r t h e r p u l v e r i z e d . T h e e n t i r e a m a l g a m i s t h e n finely g r o u n d with 8 p a r t s of f l o w e r s of s u l f u r and 6.8 p a r t s of finely p u l v e r i z e d N H4C 1 . T h e m i x t u r e i s t h e n t r a n s f e r r e d to a H e s s i a n c r u c i b l e , which m a y b e l o o s e l y c o v e r e d with a c l a y o r p o r c e l a i n lid. T h e r e a c t i o n m i x t u r e i s m o d e r a t e l y h e a t e d (about 400°C) on a s a n d b a t h for s o m e l e n g t h of t i m e , e i t h e r u n d e r a good hood o r , s t i l l b e t t e r , in t h e o p e n (caution: m e r c u r y v a p o r ) . T h e h e a t i n g i s c o n t i n u e d until no f u r t h e r v a p o r s a r e l i b e r a t e d . T h e t e m p e r a t u r e i s t h e n q u i c k l y r a i s e d t o r e d h e a t . A s s o o n a s S v a p o r s b e g i n to e v o l v e o r t h e b r o w n m a s s b e g i n s to b l a c k e n at s o m e p o i n t s , t h e h e a t i n g is s t o p p e d and t h e c r u c i b l e i s s l o w l y c o o l e d without i n c r e a s i n g t h e m o v e m e n t of a i r . Depending on t h e c h a r g e , t h e r e a c t i o n will l a s t f r o m 3 to 4 h o u r s . After c o o l i n g , t h e c r u c i b l e i s c a r e f u l l y b r o k e n and t h e well c r y s t a l l i z e d u p p e r l a y e r , w h i c h g l i s t e n s l i k e g o l d , i s s e p a r a t e d . T h e l a y e r s b e l o w t h e t o p m o s t a l s o c o n t a i n S n S2. H o w e v e r , it i s p r e s e n t in l e s s well d e v e l o p e d c r y s t a l s . T h e b o t t o m l a y e r often c o n t a i n s s o m e p u r e S. If t h e i n i t i a l c h a r g e i s too l a r g e , d e c o m p o s i t i o n of t h e p r o d u c t (black d i s c o l o r a t i o n ) due to o v e r h e a t i n g m a y o c c u r at t h e b o t t o m and on t h e w a l l s b e c a u s e of t h e p o o r h e a t t r a n s f e r , while t h e c e n t e r c h a r g e m a y not r e a c t t h o r o u g h l y . T h e b e s t

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c r y s t a l l i z i n g l a y e r i s p u r i f i e d by s u b l i m a t i o n on t h e s a n d b a t h . T h e t r a n s l u c e n t f l a k e s of S n S2 t h u s o b t a i n e d h a v e a b e a u t i f u l gold s h e e n ; t h e y i e l d i s about 50%.

T h i s p r o d u c t , u n d e r t h e n a m e of " m o s a i c g o l d , " i s u s e d in t h e p a i n t i n d u s t r y . A s " t i n - b r o n z e , " it i s a l s o e m p l o y e d for b r o n z i n g . I n s t r u c t i o n s f o r p r e p a r i n g p r o d u c t s w i t h s o m e w h a t b r i g h t e r o r r e d d e r c o l o r t o n e s a r e given in t h e a p p e n d e d o r i g i n a l

l i t e r a t u r e .

PROPERTIES:

F l a k y o r s c a l y c r y s t a l s w i t h a h i g h g o l d - y e l l o w s h e e n , soft a s t a l c ; v e r y s t a b l e in a i r . On h e a t i n g , t h e c o l o r d e e p e n s r e v e r s i b l y t o d a r k r e d , t h e n t o d e e p b r o w n , a b o v e about 600°C d e c o m p o s i t i o n to SnS and S t a k e s p l a c e ; d 4 . 5 .

Insoluble in w a t e r and m i n e r a l a c i d s ; s o l u b l e (with c h e m i c a l change) in a q u a r e g i a , a l k a l i sulfide and a m m o n i u m sulfide s o l u ­ t i o n s .

C r y s t a l s : C6 s t r u c t u r e t y p e .

REFERENCES:

W. O b s t . F a r b e und L a c k 1927, 5 7 . H. H a d e r t . C h e m i k e r - Z t g . 50, 7 (1926).

J . L a g u t t . Angew. C h e m . 1897, 5 5 7 .

Sodiu m Metathiostannat e Na2SnS3 · 8 H20

Na4SnS4 + SnS2 = 2 Na2SnS3

(18 H20 ) (8 H20 ) 663.2 182.8 810.0

A s o l u t i o n of 50 g. of p u r e N a4S n S4 · 18 H20 ( s e e t h e following p r e p a r a t i o n ) in 1.5 l i t e r s of d i s t i l l e d w a t e r i s p r e p a r e d . T h i s s o l u t i o n i s t i t r a t e d at t h e b o i l i n g point with I N HC1 u n t i l a s a m p l e of t h e liquid g i v e s a y e l l o w c o l o r w i t h b r o m o c r e s o l g r e e n (pH 4 - 5 ) . To c o m p l e t e t h e s e p a r a t i o n of S n S2, t h e m i x t u r e i s b o i l e d gently f o r 4 h o u r s . After cooling, t h e p r e c i p i t a t e i s v e r y c a r e f u l l y w a s h e d and d e c a n t e d 10 t i m e s ( t h i s t a k e s s e v e r a l days) a n d t h e e x c e s s liquid i s r e m o v e d in a leaf f i l t e r . T h e p u r e S n S3 i s d r i e d at 120°C and finely p u l v e r i z e d . T h e b r o w n i s h p o w d e r i s t h e n p l a c e d in a b o i l i n g s o l u t i o n of 50 g. of N a4S n S4 · 18 HsO in 100 m l . of d i s ­ t i l l e d w a t e r , w h i c h c o n t a i n s a few Sn g r a i n s f o r p r o t e c t i o n a g a i n s t a i r o x i d a t i o n . H e a t i n g i s c o n t i n u e d u n t i l t h e r e a c t i o n (with d i s ­ s o l u t i o n of t h e SnS2) i s c o m p l e t e d . T h e m i x t u r e i s t h e n e v a p o r a t e d

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1 3 . T I N A N D L E A D 743 and t h e c o n c e n t r a t e d s o l u t i o n i s left s t a n d i n g in a c r y s t a l l i z i n g d i s h o v e r C a C l3. T h e c o l o r l e s s s a l t p r e c i p i t a t e i s s e p a r a t e d f r o m t h e m o t h e r l i q u o r , w a s h e d w i t h s o m e i c e - c o l d w a t e r , a n d p u r i f i e d by d o u b l e r e c r y s t a l l i z a t i o n f r o m w a t e r . Y i e l d : 37 g. of a n a l y t i c a l l y p u r e N a2S n S 3 · 8 H20 .

PROPERTIES:

F o r m u l a w e i g h t 4 0 5 . 0 2 . C o l o r l e s s , p r i s m a t i c c r y s t a l s , w h i c h l o s e t h e i r w a t e r of c r y s t a l l i z a t i o n in v a c u u m o v e r P20B o r by h e a t i n g t o 2 0 0 - 2 5 0 ° C . R e a d i l y s o l u b l e in w a t e r ; 100 g. of s o l u t i o n a t 16°C c o n t a i n s 3 8 . 1 g. of NagSnSg · 8 H30 .

REFERENCE:

Ε. E . J e l l e y . J . C h e m . Soc. (London) 1933, 1580.

Sodiu m Tefrathiostcmnat e (IV) N a4S n S41 8 H20

Na2Sn(OH)e + 4 Na2S = Na4SnS4 + 6 NaOH

( 9 H20 ) ( 1 8 H20 ) 266.7 960.8 663.2

F o r t h e p r e p a r a t i o n , 100 g. of t e c h n i c a l g r a d e N a2S n ( O H )e

(about 80% p u r e ) a n d 250 g. of N a3S · 9 HaO a r e d i s s o l v e d in 700 m l . of b o i l i n g d i s t i l l e d w a t e r . T h e s o l u t i o n , c o l o r e d g r e e n i s h - b l a c k by i m p u r i t i e s c o n t a i n e d in t h e s t a n n a t e , i s h e l d f o r 3 h o u r s a t 90 to 100°C. T h e n 40 g. of finely p u l v e r i z e d MgO i s a d d e d a n d t h e s o l u t i o n i s h e a t e d f o r a n o t h e r 2 - 3 h o u r s . T h e p r e c i p i t a t e d i m p u r i t i e s a r e s u c t i o n - f i l t e r e d a n d t h e s l i g h t l y y e l l o w f i l t r a t e i s c o n c e n t r a t e d on a w a t e r b a t h t o a b o u t 300 m l . On s t a n d i n g , c o l o r l e s s N a4S n S4 · 18 HsO s e p a r a t e s out. T h e s a l t i s p l a c e d on a f r i t t e d g l a s s f i l t e r , w a s h e d w i t h s o m e i c e - c o l d w a t e r , a n d p u r i f i e d by d o u b l e r e c r y s t a l l i z a t i o n f r o m w a t e r . T h e p r o d u c t i s t h e n p l a c e d on a c l a y p l a t e a n d d r i e d f o r a s h o r t t i m e in a i r . It t h e n h a s t h e c o m p o s i t i o n i n d i c a t e d by t h e f o r m u l a . On l o n g e r d r y i n g , p a r t of t h e w a t e r of c r y s t a l l i z a t i o n i s l o s t . Y i e l d : 80 g. of N a4S n S4 · 18 H20 .

PROPERTIES:

C o l o r l e s s , c r y s t a l l i n e s u b s t a n c e ; l o s e s p a r t of i t s w a t e r of c r y s t a l l i z a t i o n on long s t a n d i n g in a i r o r in v a c u u m o v e r P3Os o r on h e a t i n g t o 2 0 0 - 2 7 0 ° C ; t h e l a s t two m o l e s a r e g i v e n off only at

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r e d h e a t , but s i m u l t a n e o u s d e c o m p o s i t i o n of t h e s a l t t o SnS and N a2Sx o c c u r s .

R e a d i l y s o l u b l e in w a t e r (57.1 g. in 100 g. of s o l u t i o n a t 18°C).

Monoclinic c r y s t a l s .

REFERENCE:

Ε. E . J e l l e y . J . C h e m . Soc. (London) 1 9 3 3 , 1 5 8 0 .

Tin (IV) Sulfat e S n( S 04)2- 2 H20

T h e p r e p a r a t i o n s t a r t s f r o m α - s t a n n i c and s u l f u r i c a c i d s . F r e s h l y p r e c i p i t a t e d α - s t a n n i c a c i d ( s e e p . 737) i s d i s s o l v e d in a n e x c e s s of hot, d i l u t e s u l f u r i c a c i d , and t h e c o l o r l e s s s o l u ­ t i o n i s e v a p o r a t e d . W h i t e c r y s t a l s of S n ( S 0 4 )2 · 2 H20 s e p a r a t e . T h e s e a c q u i r e a n e e d l e - s h a p e d , p l a t e l i k e , o r p r i s m a t i c a p p e a r ­ a n c e w i t h i n c r e a s i n g a c i d c o n c e n t r a t i o n . A f t e r c o o l i n g , t h e s a l t i s s u c t i o n - f i l t e r e d t h r o u g h a f r i t t e d g l a s s c r u c i b l e and left f o r s o m e t i m e s in a d e s i c c a t o r , on c l a y and o v e r PaOB, in o r d e r t o f r e e it of t h e m o t h e r l i q u o r . T h e p u r e p r o d u c t m u s t b e s t o r e d in s e a l e d a m p o u l e s , s i n c e it i s v e r y h y g r o s c o p i c .

PROPERTIES:

F o r m u l a w e i g h t 3 4 6 . 8 5 . C o l o r l e s s , c r y s t a l l i n e s u b s t a n c e ; v e r y h y g r o s c o p i c . H y d r o l y z e s c o m p l e t e l y in w a t e r , w i t h s e p a r a t i o n of α - s t a n n i c a c i d . R e a d i l y s o l u b l e in d i l u t e s u l f u r i c a c i d .

REFERENCES:

A. D i t t e . C o m p t e s R e n d u s Hebd. S e a n c e s A c a d . Sci. 104, 172 (1887).

Tetramethylti n Sn(CH3)4

The s m o o t h e s t c o n v e r s i o n a n d t h e b e s t y i e l d s a r e o b t a i n e d in t h e G r i g n a r d r e a c t i o n w h e r e b y S n C l4 i s t r e a t e d w i t h a C H3M g B r s o l u t i o n :

4 Mg + 4 CH3Br ( 4 CH3MgBr

97,3 379,8

4 CH3MgBr + SnCl4 ( e t h e r ) Sn(CH3)4 + 4 Mg(Cl, Br)2

260.5 178.8

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1 3 . T I N A N D L E A D 7 4 5 T h e G r i g n a r d r e a g e n t ( C H3M g B r ) i s p r e p a r e d in a 1 - l i t e r , t w o - n e c k f l a s k p r o v i d e d w i t h a r e f l u x c o n d e n s e r and a g a s i n l e t t u b e r e a c h i n g t o t h e b o t t o m . A C a C la d r y i n g t u b e i s a t t a c h e d to t h e end of t h e c o n d e n s e r t o p r e v e n t a c c e s s of a t m o s p h e r i c m o i s t u r e . T h e f l a s k i s c h a r g e d w i t h 2 4 . 5 g. of Mg s h a v i n g s (about 1 g r a m - a t o m ) a n d 500 m l . of c a r e f u l l y d r i e d e t h e r . T h e r e a c t i o n i s i n i t i a t e d w i t h about 1 g. of " a c t i v a t e d " Mg t u r n i n g s . T h e s e a r e p r e p a r e d a s f o l l o w s : About 1 g . of Mg t u r n i n g s and 0.5 g. of I2 a r e c a r e f u l l y h e a t e d in a d r y t e s t t u b e o v e r a f r e e f l a m e , u n t i l m o s t of t h e iodine s u b l i m e s onto t h e cool p a r t of t h e t u b e . After cooling in a d e s c i c a t o r t h e t u r n i n g s , w h i c h a r e c o v e r e d with a b r o w n i s h l a y e r , a r e p l a c e d in t h e r e a c t i o n f l a s k . P u r e C H3B r f r o m a c y l i n d e r o r f r o m a c o o l e d supply t r a p i s slowly a d d e d t o t h e liquid v i a t h e g a s i n l e t t u b e . If t h e c o n v e r s i o n t o C H3M g B r d o e s not s t a r t within 3 m i n u t e s (which c a n b e r e c o g n i z e d by t h e p e r s i s t e n c e of t h e iodine c o l o r ) t h e n t h e C H3B r flow i s i n t e r r u p t e d a n d t h e f l a s k i s c a r e f u l l y h e a t e d on a w a t e r b a t h t o 60 t o 70°C. A v e s s e l filled with i c e w a t e r m u s t b e on h a n d t o p e r - m i t r a p i d c o o l i n g if t h e r e a c t i o n i s t o o v i g o r o u s . O n c e t h e r e a c t i o n s t a r t s , t h e a d d i t i o n of C H3B r i s s o r e g u l a t e d t h a t t h e e t h e r r e - m a i n s at a m o d e r a t e b o i l . It i s a b s o l u t e l y n e c e s s a r y in f u r t h e r p r o c e s s i n g t h a t t h e Mg b e c o m p l e t e l y d i s s o l v e d . About 120 g. of C H3B r (about 1.25 m o l e s ) i s n o r m a l l y n e e d e d t o a c c o m p l i s h t h i s , but c o n s i d e r a b l y m o r e m a y b e if t h i s r e a g e n t i s i n t r o d u c e d t o o r a p i d l y . In t h e l a t t e r c a s e , m o s t of t h e m e t h y l b r o m i d e e s c a p e s t h r o u g h t h e c o n d e n s e r without r e a c t i n g . If n e c e s s a r y , t h e l a s t t r a c e s of Mg c a n b e c o n v e r t e d by a d d i n g about 5 g, of CHgl t h r o u g h t h e r e f l u x c o n d e n s e r . After t h e a d d i t i o n , t h e r e a c t i o n m i x t u r e i s r e f l u x e d f o r half a n h o u r on t h e w a t e r b a t h . T h e f l a s k i s t h e n c l o s e d off w i t h a C a C ls t u b e a n d a l l o w e d t o s t a n d a t r o o m t e m - p e r a t u r e u n t i l f u r t h e r u s e .

T h e r e a c t i o n w i t h S n C l2 i s c a r r i e d out u n d e r a hood, u s i n g a t h r e e - n e c k , 1 - l i t e r g r o u n d g l a s s f l a s k p r o v i d e d w i t h a r e f l u x c o n d e n s e r , a w e l l - s e a l e d s t i r r e r a n d a d r o p p i n g funnel. Both t h e c o n d e n s e r a n d t h e d r o p p i n g funnel a r e e q u i p p e d w i t h C a C ls d r y i n g t u b e s . T h e S n C l4 c a n n o t b e a d d e d d i r e c t l y t o t h e G r i g n a r d r e a g e n t , a s i s u s u a l l y done in a n a l o g o u s p r e p a r a t i o n s . T h i s r e a c t i o n i s t o o v i o l e n t s i n c e e v e n t h e r e a c t i o n of S n C l4 w i t h e t h e r , w h i c h y i e l d s a c r y s t a l l i n e e t h e r a t e , i s v e r y e x o t h e r m i c . It i s t h e r e f o r e m u c h m o r e p r a c t i c a l to p r e p a r e t h i s e t h e r a t e s e p a r a t e l y and t h e n a d d t o it t h e G r i g n a r d s o l u t i o n .

T h e r e a c t i o n f l a s k i s c h a r g e d w i t h 200 m l . of a b s o l u t e e t h e r , and 4 5 g. of a n h y d r o u s S n C l4 ( s e e p . 729) i s a d d e d d r o p w i s e , w h i l e v i g o r o u s l y s t i r r i n g a n d c o o l i n g w i t h i c e w a t e r . A f t e r t h e a d d i t i o n , t h e d r o p p i n g funnel i s r e p l a c e d with a c l e a n o n e a n d t h e e t h e r e a l solution of CHgMgBr i s added o v e r a p e r i o d of 45 m i n u t e s w i t h v i g o r o u s a g i t a t i o n . T h a t a d d i t i o n p r o c e e d s at r o o m t e m p e r a t u r e .

(20)

T h e r e a c t i o n i s c o m p l e t e d by r e f l u x i n g for 2 d a y s ( t w i c e for 10 h o u r s ) on t h e w a t e r b a t h . T h e p r o d u c t i s t h e n c h e c k e d for m a l ­ o d o r o u s m e t h y l t i n h a l i d e s w h i c h a r e i n i t i a l l y p r e s e n t . If t h e o d o r i s p r e s e n t , r e f l u x i n g m u s t b e c o n t i n u e d . T h e r e a c t i o n m i x t u r e i s t h e n c a r e f u l l y d e c o m p o s e d w i t h d i s t i l l e d w a t e r f r o m t h e d r o p p i n g funnel. T h e f l a s k m u s t b e c o o l e d w i t h i c e w a t e r , and a d d i t i o n i s c o n t i n u e d u n t i l t h e i n i t i a l e f f e r v e s c e n c e s u b s i d e s . F i n a l l y , 10%

h y d r o c h l o r i c a c i d i s added u n t i l t h e p r e c i p i t a t e d Mg s a l t d i s s o l v e s c o m p l e t e l y and two l a y e r s c a n b e o b s e r v e d in t h e s o l u t i o n (if n e c e s s a r y , l e t s t a n d for s o m e t i m e ) . T h e e t h e r l a y e r i s s e p a r a t e d in a s e p a r a t o r y funnel and w a s h e d s u c c e s s i v e l y w i t h s o m e w a t e r and a 5% K F s o l u t i o n . Any m e t h y l t i n h a l i d e s s t i l l p r e s e n t a r e t h u s c o n v e r t e d to t h e c o r r e s p o n d i n g f l u o r i d e s . T h e s e a r e i n s o l u b l e and c a n b e f i l t e r e d off. T h e e t h e r s o l u t i o n i s d r i e d for s e v e r a l h o u r s w i t h C a C l2. T h e n m o s t of t h e s o l v e n t i s r e m o v e d in a slow d i s t i l l a t i o n w i t h a s u i t a b l e c o l u m n . T h e r e m a i n d e r i s f r a c ­ t i o n a t e d at a t m o s p h e r i c p r e s s u r e , u s i n g t h e s a m e c o l u m n . T h e boiling point of t h e p u r e s u b s t a n c e i s 76°C. T h e y i e l d c o r r e ­ s p o n d s to about 90% of t h e o r e t i c a l , b a s e d on t h e S n C l4 u s e d .

PROPERTIES:

W a t e r - c l e a r , highly r e f r a c t i v e , m o b i l e liquid w i t h a n a g r e e a b l e , s w e e t , e t h e r o d o r ; p o i s o n o u s ; s t a b l e t o a i r and w a t e r . B . p . 76°C, df5 1.291. I n s o l u b l e in w a t e r ; m i s c i b l e in a l l p r o p o r t i o n s w i t h e t h e r , a b s o l u t e a l c o h o l and o t h e r o r g a n i c s o l v e n t s .

REFERENCES:

F . O s s e n b r i n k . T h e s i s , C o l o g n e , 1952; s e e A l s o E . K r a u s e and A. von G r o s s e . Die C h e m i e d e r m e t a l l - o r g a n i s c h e n V e r b i n d u n - g e n , B e r l i n , 1937, p . 314 ff.

Tetraethylti n Sn(C2H5)4

4 C2H5Br + 4 Mg = 4 C2H5MgBr

435.9 97.3

4 C2H5MgBr + SnCl4 = Sn(C2H5)4 + 4 Mg(Cl, Br)2

260.5 234.9

T h e p r e p a r a t i o n i s a n a l o g o u s to t h a t of S n ( C H 3 )4. T h e r e a d e r i s r e f e r r e d t o t h e d e t a i l e d d e s c r i p t i o n of t h e p r o c e d u r e g i v e n u n d e r t h a t c o m p o u n d , u n l e s s c h a n g e s a r e e x p r e s s l y i n d i c a t e d in w h a t f o l l o w s .

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