BRIEF COMMUNICATIONS

DIPOLE MOMENTS OF para-SUBSTITUTED

E. A. Ishmaeva, F. M. Kharrasova, A. P. Zav'yalov, and A. N. Pudovik

P H E N Y L P H O S P H O N A T E S

UDC 539.143.43+G61.7118.1

As a continuation of our studies of organophosphorus compounds we determined the dipole moments of some p-subst i tu ted phenylphosphonates. By introducing various substituents in the p-posi t ion of the phenyl ring (C1, Br, CH 3, CH~O) we hoped to obtain some information on the t r ans fe r of the effect of sub- stituents to the diethoxyphosphono group.

In calculating the dipole moments we started with the assumption that a planar arrangement of the phenyl ring and the phosphoryl group is the most favorable [I, 2]..The orientation of the molecule in the coordinate system is shown in Fig. I. The valence angles at the phosphorus atom were adopted on the basis of the data given in [3], while the moment of the Csp2-H bond is taken equal to 0.70D [4]. The dipole mo- ments of the Csp2- X bonds were calculated by the additive scheme [4] from the experimental dipole mo- ments [5] of the corresponding substituted benzenes: X = C1 0.89, Br 0.86, CH 3 1.06 D. In this connection the interact ion between the substituent and the phenyl r ing was also taken into account. The moments of the bonds in the methoxy group are given in [3]. Analogous to [3], we postulated that s t ruc tures with differently oriented methoxy groups should be presen t in the mixture in equal amounts.

The dipole moments of the diethyl e s t e r s of the p-subst i tu ted phenylphosphonic acids were calculated on the basis of the diethoxyphosphono group having a moment of 2.30 D, with such an orientation of this group that the components along the coordinate axes (see Fig. 1) have the values: m x = 0.72, my = 0, m z = 2.19D [3]. The moment of the Csp2- P bond = 0.69D was determined f rom the experimental dipole moment of the diethyl es te r of phenylphosphonic acid. The dipole moments of the p-subst i tu ted phenytphosphonates, calcu- lated on the basis of these data, a re given together with the experimental dipole moments in Table 1. The calculated dipole moments do not coincide with the experimental values, which is evidently caused by the interact ion of the p-subst i tuents with the diethoxyphosphono group. The t r ans fe r of e lectrons f rom a donor substituent to the diethoxyphosphono group along the direct ion f rom the halogen atoms or the oxygen of the methoxyl group is charac te r i zed by the moment of interaction, which is d i rected along the x axis (see Fig. 1). The moments of interaction for the diethyl e s t e r s of p -methoxy- and p-halophosphonic acids a re ap- p roximate ly 1 D, which indicates substantial involvement of the diethoxyphosphono group in the common conjugation chain.

We also determined the dipole moment of phenylphosphonyl dichloride (3.99 D). The valence angle of Csp2- P = O was taken equal to 116 ~ [2]. the dipole moment of the P = O bond was taken equal to 3.21D (calculated f rom the experimental dipole moment of phosphorus oxychloride [5]), and the moment of the

OC~H 5

Fig. 1. For calculating the dipole moments of p - sub- stituted phenylphosphonates: C = H , CH3, CH30 , CI, Br.

P - CI bond was taken equal to 0.66 D (calculated f rom the experimental dipole moment of phosphorus t r ichlor ide [5]). The dipole moment of the Csp2- P bond, calculated on the basis of the given data f rom ~he experimental dipole moment of phenylphosphonyl dichloride, is equal to 0.70D, and prac t ica l ly coincides with the moment of the C s p 2 - P bond, calculated f rom the unsubstituted phenylphosphonate (0.69 D).

The corre la t ion of the experimental dipole moments of the di- ethyl es te r s of p-subst i tuted phenylphosphonates with the crH- substi- tuents in the phenyl ring was found; the correla t ion coefficient [s r = 0.999 and p = -0 .997.

V. L Ul 'yanov-Lenin Kazan State Universi ty. Trans la ted f rom Izvest iya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 619-620, March, 1971. Original ar t ic le submitted May 25, 1970.

�9 1971 Consultants Bureau, a division of Plenum Publishing Corporation, 227 West 17th Street, New York, N. Y. 10011. All rights reserved. This article cannot be reproduced for any purpose whatsoever without permission of the publisher, d copy of this article is available from the publisher for $15.00.

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TABLE 1. Dipole Mo- ments (D) of Com- pounds p-XC6H4P (O) �9 (OC2H5) 2

X Pcalc /~exp Pinter

CH3 c1 Br CH~O

3,30 2,25 2,26 3,21

3,23 2,83 2,84 3,34

• 4,27 4,22 0,98

TABLE 2. Coefficients of Calcu- lation Equations and Exper imen- tal Di)ole Moments of p-XC6H4P(O )

X a 7 P0, crna Pexp' D

H CH~ CH30 C1 Br

8,588 9,014 8,931 6,475 5,366

0,168 0,088 0,135 0,t79 0,089

190,45t 2t5,265 226,830 t65,301 i63,448

3,04 3,23 3,31 2,83 2,8i

EXPERIMENTAL METHOD

The diethyl e s t e r s of the p-subst i tu ted phenylphosphonic acids were synthesized as descr ibed in [6]�9 The dipole moments were determined in CCI 4 at 25 ~ The dielectr ic permeabi l i t ies of the solutions were determined on an IDM-2 instrument [7], while the ref rac t ive indices were determined on an IRF-23 re - f rac tometer . The orientation polar izat ion was calculated by the Guggenhe im- Smith method [8]�9 The coefficients of the calculation equations and the resul t ing data are given in Table 2.

C O N C L U S I O N S

1. The dipole moments of some p-subst i tu ted phenylphosphonates were determined�9

2. In the investigated compounds the diethoxyphosphono group takes a substantial par t in the con- jugation with the substituents in the phenyl ring.

i�9

2.

3.

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5.

6.

7.

8.

LITERATURE CITED

M. I. Kabachnik. T. A. Mastryukova, and T�9 A�9 Melent'eva, Zh. Obshch. Khim.. 3._33, 382 (1963). L�9 V. Vilkov, N. I. Sadova, and I. Yu. Zil 'berg, Zh. Strukt�9 Khim., 8, 528 (1967). E. A. Ishmaeva, A. N. Vereshchagin, N.A. Bondarenko, G. E. Yastrebova, and A. N�9 Pudovik, Izv. AN SSSR, Ser. Khim�9 2695 (1970). L. A. Gribov and E�9 M. Popov, Dokl. AN SSSR, 145, 761 (1962). O. A. Osipov and V. I. Minkin, Handbook on Dipole Moments [in Russian], Vysshaya Shkola (1965). H. Z. Lecher , R. A. Greenwood, K. C. Whitehouse, and T. H. Chao, J. Amer . Chem. Soc., 78, 5018 (1956); F. M. Kharrasova, G. Kh. Kamai, and G. I. Matveeva, Zh. Obshch. Khim., 3__~8, 1262 (1968). R. Sh�9 Nigmatullin, M. R. Vyaselev, and V. S. Shatunov, Zavodsk. Lab., 500 (1964). E. A�9 Guggenheim and J. E. l>rue, Physicochemical Calculations [Russian translation], IL (1958), p. 100.

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