4-(4-Hydroxy-3,5-dimethylphenylazo)benzenesulfonic Acid

Abstract

O(1)----C(7) 1.218 (8) C(1)---C(2) 1.516 (9) O(2)----C(8)1.231 (8)Intensities were corrected for Lorentz and polarization effects. The structure was solved by direct methods using MITHRIL (Gilmore, 1984 NOELLE EHLINGER AND MONIQUE PERRIN 1847 1993). The properties of these azocalixarenes are often compared with those of their non-cyclic analogues (Shinkai et al., 1989;Nomura, Taniguchi & Tamura, 1989;Nomura, Taniguchi & Otsuji, 1993). It is for this purpose that we describe here the crystal structure of 4-(3,5-dimethyl-4-hydroxyphenylazo)benzenesulfonic acid. The crystallization of this product gives two kinds of crystals of the monohydrate: cubes (I) and needles (II). In (I), intermolecular hydrogen bonds have been found between the water molecule and 0(2) and 0(4) of two sulfonic groups, and O(1) of the hydroxy group. There is also a bifurcated hydrogen bond between N(2) and two O atoms [0(2) and 0(4)] of two sulfonic groups, an H atom being located at 0.959/~ from N(2). This interaction corresponds to a charge-transfer interaction because a proton was transferred from the sulfonic group to N(2) of the azo group. MeIn (II), intermolecular hydrogen bonds have been found between the water molecule and 0(3) and 0(4) of two sulfonic groups, and O(1) of the hydroxyl group. We also find a fourth interaction between N(2) and 0(2) which corresponds to a charge-transfer interaction, the H atom being located at 0.945/~, from N(2).A-5-Z. ExperimentalThe title compound was prepared by a diazo coupling reaction of 2,6-dimethylphenol and diazoted sodium sulfanilate in water at ca 275 K. At the end of the reaction, the red solution was treated with hydrochloric acid and p-(4-hydroxy-3,5-dimethylphenylazo)benzenesulfonic acid was isolated by filtration and recrystallized from water (63% yield). IH NMR (D20): 6 2.18 (6H, s, CH3), 7.43 (2H, s, ArH in the phenol moiety), 7.70 and 7.87 p.p.m. (both 2H, d, ArH in the 4-sulfonic phenyl moiety). Elemental analysis: calculated for Cn4HI4N204S.H20, C 51.84, H 4.97, N 8.64, S 9.88%; found, C 51.70, H 4.91, N 8.66, S 9.89%. Form (I) Crystal dataCI4Hi4N204S.H20 NOELLE EHLINGER AND MONIQUE PERRIN 18492.541 (4) 151 ( -177.9 In both structures, H atoms bonded to C atoms were placed in calculated positions. H atoms bonded to N atoms and O atoms were located in difference maps. ©1995 International Union of CrystallographyPrinted in Great Britain -all rights reserved AbstractIn the molecule of the title compound, C15H1502P, the C==C--~ fragment has an S-cis conformation. The methoxyphenyl ring assumes an almost coplanar arrangement with the ~ bond and is almost perpendicular to the phenyl ring.

Monosulfonated Azo Dyes: A Crystallographic Study of the Molecular Structures of the Free Acid, Anionic and Dianionic Forms

“…The most common result on crystallising monosulfonated azo dyes from low pH aqueous systems is to obtain a solid-state form with protonation of the N atom of the azo group that is bonded to the sulfonate bearing aromatic ring, see Figure 2 for example. Ten of the thirteen free acid structures reported herein adopt similar zwitterionic forms and this is also the commonest form previously reported for crystal structures of similar dyes [17,[24][25][26]. The structure obtained for H9 is…”

“…The discussion will centre on the structures of 17 azo species called 1 to 17 in Scheme 1. Of these, the structures of H1, H5, H7, H12, and H13 are taken from the literature and the other structures are presented here [17,[24][25][26]. Of the free acid species, eight are of special interest, as the structures of their deprotonated, Na salt forms are available for comparison.…”

Supramolecular motifs in s-block metal bound sulfonated monoazo dyes

“…Similar distances were found in the 3,5-dimethylated analogue. 14 The effect of a second resonance structure (Scheme 2) is further shown by the marked pattern of long and short C-C bonds found in the phenol ring (Table 3) which suggest a considerable quinonoid contribution to the overall structure. This supports the conclusions of earlier work 9 based on solid-state 13 C and 15 N NMR which showed an enhanced positive charge at C10.…”