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BAND 26 b ZEITSCHRIFT FÜR NATURFORSCHUNG HEFT 9

Chelating Tendencies of some N-(2-Acyl-l,3-Indandione) Tri Alkyl Ammonium Iodides

M . K . B A C H L A U S * , K . L . M E N A R I A * * , a n d P . N A T H * *

Dept. of Chemistry, M.B.M. Engineering College, University of Jodhpur, Jodhpur (Rajasthan), India

(Z. Naturforsdi. 26 b, 865—869 [1971] ; received May 17, 1971)

The L-T.M.A.I. and L-T.E.A.I. have been synthesised and their dissociation constants are 7.943 x l O - 1 0 and 1.413 x 10 — 1 0 respectively. The Potentiometrie studies show that these reagents form 1 : 1 complex with copper (II) and iron (II). The stability constants of copper complex and iron complex with L-T.M.A.I. are 5.75 and 6.05 respectively and for L-T.E.A.I., 5.97 and 6.215 respectively. The free energy of complex formation at 25 ° C are 7841 cals/mole and 8150 cals/mole for Cu (II)-L-T.M.A.I. and Fe (II)-L-T.M.A.I. respectively, whereas the free energy of the Cu(II)-L-T.E.A.I. and Fe (II) -L-T.E.A.I. are 8141 cals/mole and 8375 cals/mole respectively.

Recent survey of the literature reveals that there is a growing tendency to prepare reagents which are stable and more soluble so that they can be more useful f o r analytical methods viz. conductometry, potentiometry and polarography. Most commonly used solubilising groups are — O H , — COOH, — S 0 2 0 H , and the quaternary ammonium group. Y O E KLOOSTER 2 , a n d EPPHRAIM 3 h a v e s t u d i e d the effect of introducing such solubilising groups and have shown that the introduction of such groups does not appreciably effect the properties of the complex-forming groups but yields water soluble inner complex anions rather than the usual insoluble innercomplex precipitate with metal ions. COOK and MARTIN4 have studied the chelating tendency of some substituted 2 - (Pyr idy l ) and 2 - ( q u i n o l y l ) - l , 3 -indandiones with bivalent metals and have also re-ported the formation constants of these metal c om-plexes. The present work was therefore undertaken to prepare such reagents and to study their detailed properties.

The present paper communicates the synthesis of reagents possessing a trialkyl ammonium group. This group possesses greater solubilising action than the corresponding acid groups. Accord ing ly N-( 2-acyl- l ,3- indandione) trimethyl ammonium iodide (L-T.M.A.I . ) and TV-(2-acyl-l ,3-indandione) tri-ethyl ammonium iodide (L-T.E.A.I . ) have been syn-thesised. The chelating properties of these reagents

Reprints request to Dr. M. K. BACHLAUS, Defence Labora-tory, Jodhpur, India.

* Defence Lab oratory, Jodhpur, India. ** Department of Chemistry, University of Jodhpur, Jodhpur,

India. 1 J. H. YOE, J. Amer. chem. Soc. 54, 4139 [19321. 2 H . S . V A N KLOOSTER, J. A m e r . chem. S o c . 4 3 , 7 4 6 [ 1 9 2 1 ] . 3 E . EPHRAIM, Chem. Ber. 6 3 , 1 9 2 8 [ 1 9 3 0 ] .

with transition metal ions such as c o p p e r ( I I ) and iron ( I I ) have been studied by Potentiometrie and gravimetric methods. The /5-ketoalkylation reaction of heterocyclic tertiary bases as reported by KING 5 ' 6

has been extented to aliphatic tertiary amines viz. trimethyl amine and triethyl amine, using 2-acyl-1,3-indandione giving corresponding trimethyl, tri-ethyl quaternary compounds.

R C 0 C H 3 + I2 + 2 N < } R ' © ©

- R C O C H 2 - N < } R' + H N < } R ' I® I s

where r n

R = C 6 H 4 < 2 o > C H - and R ' = ( C H 3 ) 3 , ( C 2 H 5 ) 3 .

Experimental

Preparation of 2-acyl-l,3-indandione

The 2-acyl-l,3-indandione was obtained by the reaction of dimethyl phthalate and acetone in the pre-sence of sodium methoxide according to the method of K I L G O R E 7 .

Preparation of N-(2-acyl-l,3-indandione trimethyl am-monium iodide (L-T.M.A.I.)

2-acyl-l,3-indandione (5.0 gm) was added to a solu-tion of iodine (6.5 gm) in methanol (10 ml) and tri-methyl amine (10 ml) was then added gradually with constant shaking. A vigorous reaction started imme-diately with the evolution of heat. The reaction mixture was allowed to cool and left overnight. The dark coloured solid separated was filtered and washed

4 J. R. COOK and D. F. MARTIN, J. inorg. nuclear Chem. 2 6 , 5 7 1 7 [ 1 9 6 4 ] .

5 L . C . KING, J. A m e r . d i e m . Soc. 6 6 , 8 9 4 [ 1 9 4 4 ] . 6 L . C . KING and MCWHIRTER, J. A m e r . chem. Soc. 6 8 , 7 1 7

[ 1 9 4 6 ] . 7 L . B . KILGORE, J. H . FORD, and W . C. WOLFE, Ind. E n g n g .

C h e m . 3 4 , 4 9 4 [ 1 9 4 2 ] .

|

866 M . K . B A C H L A U S , K . L. M E N A R I A , A N D P. N A T H

with little methanol to separate it from tri methyl am-monium hydro iodide. The latter being more soluble in methanol. The product was recrystallised from ab-solute alcohol. The compound is dark green crystalline solid (m.p. 221 °C —223 °C) highly soluble in water but insoluble in ether (3.5 g yield 70%). C14H16NO3I

Calc. N 3.75 I 34.04. Found N 3.65 I 37.0.

Preparation of N-(2-acyl-l,3-indandione) triethyl am-monium iodide (L-T.E.A.I.)

This was prepared by method similar to L-T.M.A.I, using trimethylamine (13 ml). It is a brown crystalline solid m.p. 131 °C —132 °C. It is highly soluble in water but insoluble in ether. It was recrystallised from absolute ethanol (3.7 gm, yield 74%). C17H22NO3I

Calc. N 3.37 I 30.6, Found N 4.0 I 33.2.

Acid dissociation constant

The acid dissociation constants have been deter-mined potentiometrically. The pH titrations are car-ried out using a Cambridge pH-meter ( ± 0 . 0 2 ) . The solution m/50 of the ligands were prepared in distilled water by accurate weighing and a known amount was titrated with alkali (NaOH) M/5 free from CO 3 2 0 . The test solution was maintained at 25 + 0.1 °C in a double-walled vessel, by circulating water from a ther-mostat and stirred by a small glass paddle. A micro-burette was used whose nozzle was dipped in the covered vessel containing the solution and the glass and calomel electrodes dipped in it.

Similar procedure was used to determine the for-mation constant. A M/50 copper sulphate (A.R.) solu-tion and M/50 M o h r's salt (AR) solution were pre-pared in distilled water by accurate weighing. All other reagents used were of analytical grade.

Gravimetric method for establishing the composition of the complex

The complex was precipitated in the pH range 5.6 — 6.0. Precipitate was filtered through a Whatmann filter paper No. 42. The precipitate was washed several

times with distilled water and then dried at 70 c C in the oven. Weigh 0.1 gm of the complex accurately in a beaker (Pyrex). The organic matter was oxidised with conc.nitric acid and evaporated to dryness. The residue was then treated with conc. sulphuric acid and evaporated to dryness. The residue was dissolved in dil. sulphuric acid and copper was determined in the solution iodometrically. The ratio of copper (II) to ligands i .e. L-T.M.A.I. and L-T.E.A.I. was 1 : 1. For results see Table I.

The organic matter was oxidised with conc. nitric acid. The residue was then ignited at 800 °C and weighed as Fe203 . The metal: ligand ratio was thus found to be 1 : 1. For results see Table I.

Name of the Percentage of Cu Percentage of complex in the complex Fe(II) in the complex

complex Theore Found Theore Found tical tical

1. Cu(II)-L-T.M.A.I . 14.4 13.65 —

2. Cu(II) -L-T.E.A.I . 13.18 13.05 - —

3. Fe(II) -L-T.M.A.I . — — 13.02 12.96 4. Fe(II) -L-T.E.A.I . — — 11.22 11.02

Table I. Metal/ligand ratio.

Calculations

Dissociation constant

BJERRUM defined the degree of formation of the proton complexes fj^ as the average no. of protons attached to the ligand. Tbe acid, dissociation con-stants (pK's) were calculated by BJERRUM'S me-thod 8 . CA - (Na® + H ® - O H ° )

CA

Where C\ is the analytical concentration of the acid. A plot of fj^ against pH gave the formation curve for the protonation of the ligand. The pH at rjh = 0.5 gave the value of pKi, see Table II.

The values were corrected by Least Square Me-thod.

Name of the Reagent Disociation Formation Formation Free Energy Free Energy constant constant of constant of Copper Ferrous Ki copper Ferrous copmlex complex

complex complex [Cals/mole] [Cals/mole]

1.Ar-(2-acyl-l,3 - indandione) -trimethyl-ammonium-iodide 2.A7-(2-acyl-l,3-indandione)-triethyl -ammonium-iodide

7.943 X 1 0 - 1 0 5 .75

1.413 X l O - 1 0 5.97

6.05

6.215

7841

8141

8150

8375

Table II. Dissociation and formation constants.

8 B. J. BJERRUM, Metal Ammine formation in aqueous solution, P. Hasse & Sons, Copenhagen 1957.

FORMATION CONSTANTS OF BIVALENT M E T A L ION CHELATES 867

Formation constant

The formation constants were calculated both graphically and by calculations. The average number of ligand molecules bound per metal ion is given by the expression

C\-(H®/K+l)A® V = CM

Where A e is the free ligand concentration and is given by the expression.

e (1 — a) CA—H® + O H e

Ae = H ®/K

The formation curve was obtained by plotting fj against — log The — \ogAe value at »7 = 0.5 gives the value of log K. The values are given in the Table II.

Further the values of the stability constants were calculated by the formula

Cx-ß{A°) K = Ae[Cu+ßA°-CA] •

where P= V + 1 • The free energy of the complex formation at 25 ° C has been calculated by the formula

-AF=RT\nk.

Results and Discussion

The dissociation of the reagent can be represented

O II

II O

e^R CH—C—CH»—N R

II 0

O II

/ v - c x

•

OH O II

C - C - C H 2 - N — R II I 9 ^ R 0

e ^ R 'C—C—CH2—N—R

II I e ^ R 0

O -

+ H®

The probable structure of the metal-complex may be represented as

/

I O

0 II

c \

f C - C - C H 2 - N >

I©

—Mr O

where R = CHS , C2H5 ; M = Cu(II), Fe(II) .

The authors' sincere thanks are due to the Director, Defence Laboratory, Jodhpur, and Prof. R. C. KAPOOR, Head of Chemistry Department University of Jodhpur for providing necessary facilities.

Formation Constants of some Bivalent Metal Ion Chelates of N(2-hydroxy-l-naphthalidene) Anthranilic Acid (Schiff Base)

R . K . M E H T A , V . C . S I N G H I , a n d R . K . G U P T A

Department of Chemistry, University of Jodhpur, Jodhpur (India)

(Z. Naturforsdi. 26 b, 867—869 [1971] ; received May 25, 1971)

Protonation constants (log and log K 2 E ) of the S c h i f f base derived from 2-hydroxy-l-naphthaldehyde and anthranilic acid and, the formation constants of certain bivalent metal ion chelates have been determined potentiometrically in 50 per cent (vol./vol.) dioxan solutions (ju = 0.1 M NaC104). The stabilities of these metal chelates are in the order, U 0 2 > Cu > Ni > Co > Zn > Cd, in which the sequence of those of first transitional metal ion chelates are in agreement with I r v i n g and W i l l i a m s order.

No systematic study of the formation constants of the protonation constants of H 2NA and formation bivalent metal ion chelates of Ar-(2-hydroxy-l-naph- constants of its metal chelates. The measurements thalidene) anthranilic acid (abbr. H 2 N A ) has been were carried out in50 per cent dioxan at 30 + 0 . 1 °C as carried out. It is, therefore, of interest to investigate the ligand and its metal chelates are insoluble in water.