IR SPECTROSCOPY OF THE PROTONATION PROCESS OF PHTHALIMIDE DERIVATIVES

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IR SPECTROSCOPY OF THE PROTONATION PROCESS OF PHTHALIMIDE DERIVATIVES

By

R. HALA.SI*, K. ERoss-KISS, and E. PUNGOR

Department of General and Analytical Chemistry, Technical University, Budapest Received April 8, 1977

In this paper from among the phthalimides, N-phthalimides and N- phenil-phthalimides substituted in para position, the behaviour of chlorine, bromine and iodine derivatives depending on pH have been studied in aqueous-acetonic solutions.

Certain derivatives of the N-phenil-phthalimides are utilized as pesti- des. On the basis of their structure they can be assumed to have different stabilities in media of different pH values. It is important to clear up this problem from the point of view of the physiological effects of the above mentioned structures, depending on the stabilization of the anions of carboxylic acid, acid amides or the derivatives of the imide acids in an appropriate medium. It seemed advisable to follow the continuous structural changes by IR spectra recorded in a series of Britton - Robinson buffer solutions.

The phthalimides and the examined substituted N-phenil-phthalimides are analogous in structure to

n.

r. acid amides. [1] The structural formula of the anion of acid amides in an appropriate medium is as follows:

this can be described with the follo,ving structures:

In the protonation process the ring cleavage is presumably accompanied by the development of amide groups which can be characterized by the following structure:

-

^c^\.e^/"^0:NHz ^e ^----

/" 0:

-(~

"';-:H

(One of the hydrogen atoms may be substituted by alkyl or aryl.)

*

Faculty of Natural Sciences and Mathematics, University Novi Sad, Yugoslavia 1*

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310 R. HALASI et al.

In the IR spectra the bands of carbonyl groups have been studied on the basis of literature on IR spectroscopy of cyclic amides, of compounds contain- ing carboxyl ion and of carboxylic acids [2-8].

Experimental

Aqueous-acetonic solutions of phthalimide, N-phenyl-phthalimide, p-chlorine-N-phenyl-phthalimide, p-bromine-N-phenyl-phthalimide and p-iodine-N-phenyl-phthalimide were prepared and solutions of different pH-values were produced with a series of the Britton-Robinson buffer solution.

The solutions contained 1 mg/ml of the substance. The samples were synthe- tized in the laboratory for organic chemistry at Novi Sad. The pH values were measured with glass-electrodes.

Of these series of solutions IR spectra were recorded in a KRS 5 cell of 1 mm thickness by means of an IR spectrophotometer Type Zeiss UR-10, under the follo"\\'ing experimental conditions:

Recording speed: 50 cm -ljmin Slit program: 4 '.

Time of total. deflection: 50 sec Spectrum scale: 12 mm/lOO cm-¹ Amplification: 7

Bandwidth: 2 . Time constant: 2

Evaluation of results

The spectra obtained are seen in Figs 1 to 5. Although the spectral bands of solvents have been compensated the total band assignation of spectra has not been dealt mth because of their strong absorption, only the changes occurring in the range of 800 to 2000 cm -1 were studied.

The structures presumed on the evaluation of spectra, and the observa- tions supporting these structures are summarized in Table 1. In Table 2 the presumed pH dependent structures are summarized, indicating the intervals of their appearance in the case of our samples.

Evaluation of the spectra shows that in acidic media (ph

<

^{3) ring}

cleaving is accompained by the formation of a -COOH group. From pH = 3 the original (imide) structure is ring cleavage and -COO- ion, then for substituted the derivatives the ring is again closing at pH values slightly differing for. each. compound.

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311

o

I

~~NH

3000 2600

o

2200

3000

Fig. 1. IR spectra of phthalimides in aqueous-acetonic solutions*

o _n

C§X~-@

C

,

3300 o

T'io[

2500 2200 1800 1L.OO

I

18 __ - - - . ,

9

!

i 10 ___ - - - -...

13

14

3000 2600 2200 1800 1400

1000

1000 cm-!

Fig. 2. IR spectra of phenyl-phthalimides in aqueous-acetonic solutions*

Subsequently we plan to use also other methods - first of all NMR spectroscopy - for the verification of the assumed structures.

The described examinations aimed at establishing the pH-ranges including components of identical properties. Results are seen in Table 2.

In addition to structures sho"wn in the Table, other similar functional components may arise.

Our further investigations will also study these possibilities.

*

v: Stretching vibration; vs. Vas: symmetrical and asymmetrical stretching vibration y: bending vibration out of plane

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312

3000 PI.

3000 2600

2600

R. HALASI et al.

~~N-@-Br

o _C o

,

2200 1800 11.00

\."GoD 2200 1800 1400

1000

1000 cm-¹

Fig. 3. IR spectra of p-bromine-phenyl-phthalimide in aqueous-acetonic solutions·

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PROTONATION PROCESS OF PHTHALIMIDE DERIVATES 313

0 "

~)l-@-l C

3000 2€00 TOf.

3000 2600 Fig. 4. IR phthalimide

11

0

2200 1500 It.OO 1000

1800 1l.OO 1000

2200 cm-¹

spectra of p-iodine-phenyl- in aqueous-acetonic solu-

tions·

0 i

C§X~-@-Cl C

I

0

3000 2600 2200 1500 11.00 1000

Plo

3000 2600 2200 1800 lL.OO 1000

crrr¹ Fig. 5. IR spectra of p-chlorine-phthalimide

in aqueous-acetonic solutions·

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314 R. HALASI et al

Table 1

ConciU-'ion dreu'71 jrom the IR spectra o/substances

Substnnce examined Sample pH

I

Structure assumed

I

Expla.nation of a.ssumption No.

©r

COOH

The stretching vibration hund

(liOO

^{cm-I) of}

CO

^{and the}

-OH

I. <0 banding vibration out of plane of

o C-:\H, -COOH

group appear

(900

^cm-I)

11

0

0 0 Solvents prevent spectral hands from

11 2

2.94

¹¹ showing the structure of spectra

©r

^c^\

©rC>H

recorded in cr:ystalline state. The hyo

o /NH

³ ^6.14 spectral bands originating from the

C

coupled vibration of the two C:.1.rhonyl

11 4

9.63

¹¹ groups arc not separated but appear

0 0

as an inflexion

The hands of -COO-ion appe~1r in 5

10.59

the spectra: the asymmetric stret-

©r::~H'

ching vibration merges with the

6 11.27 amide I band (1700-1600 cm-I).

the symmetric stretching vibration

Fig. I 7 >14 0 11 appears at 1400 cm-¹

.. _ - -

!

I

^!

s -<-0

rOyCOOH

see Sample No. 1

~~~-:\H-@

0 i

i i

!l ^I :us

() 0

H lO 6.:lO ^I1

/ ... -V-C

.

-@ _©r>~-©

(("1. " ₁₁ _H.n5 see Samples No 2,3,4-

l: . _{, ..}

....J!/'

~/'o....('

0

1~ 1O.9U

1: 11

0 0

1:1 11.l2

Fig. :! 14 >14

©r;:NH-@

see Samples Xo 5.6,7 0

I l -

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315

Table 1 (continued)

Substance examined Sample No. pH Structure assumed E."'(pianation of assumption

©r: COOH ^I

^,

15 <0

I

see Sample Xo. 1

I

o ^W-NH-@-Br

I

0

0 0

n 11

©r:>~~@-Br

¹⁶¹⁷ ^u.25^3.0

©r::>-©-Br

see Samples 2,3.4

11 11 I

I

0 0

I

18 G.DG

©r:;=N'-@-.,

19 10.81 see Samples No. 5,6,7

20 !lAO

0 ,

I The

^{bands of}

-COO

^ion

diea'ppear

Fig. 3 14 Ring is closed aga.in from the spectrum their be~nies

similar to that of imide form

©r: COOH

22 <0

o w-:m-@-Br

see Sample X o. 1 0

i

i ⁰Ii

,

©r::>-@-r

0 ¹¹ ²³ ^2.64

I

see Samples Xo. :!, 3, 4

©r::>-@-I

^I ^I1

I

0 11

0

:!4 6.:W I

rQYCOO-

:!5 9.90 !

see Samples No. 5,0, 7

:!6 11.02

~C-Nlr-~O>-I

~ L..J

2i 11.:?2

Fig. 4

:!S ^>14 Ring if; closed again H"l' Sample No. 21

L _ _ _ _ _ _ _ _ _ _ _ _ _ ^~~_____

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316 ^R.^HALASl^{et al}

TOlblc 1 ',Continued)

~uh;:;tance cxaminc-<i ;o;tructun: a", ... um('c! Explanation of asoumption

St"e Sample Xo. I

0 ^;)0 :w

11 s.ec Samples Xo.~. :3,4

,-/.~C" ^r~\ ^:11 ^t:i~)5

19l /-<Q>-CI

^:t:.! ^!,.f)5

C ¹¹ :

:

0 i

:la

Il.:!:!

@::;:"-@-"

i

see Samples Xo. 5,6, j :H l:!.SO

0

Fig. ~ :15 :> 14 Ring is closed again see Sample No. 21

Table 2

The .-tructure oj phrJurlimidc, phenyl-phthalimide and p.halO'}cn substituted phl/v.::.limide

Symhol ! H HI

()

Ii

©r:::~~a-}

Structure

o c-x-@-x OH

11 I

c

⁰11 ^oI! ^H1 ~/

Compound ~tructu",

phthalimidc

I

^I ^il

I

^III

l'hcny!-phthalimide I il

I

^ill

p-iodine-phcnyl-phthalimide

I

^I ^II

I

^ill ^\ ring closure

I

p-brominc-phenyl-phthalimidc

I

^I

j

^II ^III ring closure

p-chlor·phenyI-phthalimide i I I

I

^il ^HI ring closure

pH

4 3 1 0 4 9 10 11 I~ 13 14 14

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Summary

Structure variations of phthalimide-, N-phenyl-phthalimide and chlorine-, bromine- and iodine-N-phenyl-phthalimides substituted in para-position have been studied pH, by IR spectrophotometry in aqueous-acetonic solutions.

The examinations have been carried out in Britton-Robinson buffer series structural variations la(;ling itself to observe in the range pH = - 5 to pH = 14.

References

1. LEMPERT K.: Szerves Kemia:* Organic Chemistry, Muszaki Konyvkiado, Budapest 1976.

2. EDWARDS, O. E.-SINGH, T.: Can. J. Chem. 32, 863 (1954).

3. SHEEHAN, J. C.-BOSE, A. K.: J. Am. Chem. Soc. 72, 5158 (1950).

4. FLETT, M. ST. C.: J. Chem. Soc. 961, (1951).

5. GROVE, J. F.- WILLIS, H. A.: J. Chem. Soc. 877 (1951).

6. EHRLICH, G.: J. Am. Chem. Soc. 76, 5263, (1964).

7. EHRLICH, G.-SUTHERLAND, G. B. B. M.: J. Am. Chem. Soc. 76, 5268 (1954).

8. GORE, R. C.-BARl\X;S, R. B. -PETERSEN, E.: Anal. Chem. 21, 382 (1949).

Prof. Dr. Erno PUNGOR }

Dr. Klara ERoss-KISS H-1521Budapest

R6zsa HAL..~SI University Novi Sad, Yugoslavia

• In Hungarian

IR SPECTROSCOPY OF THE PROTONATION PROCESS OF PHTHALIMIDE DERIVATIVES