2,6-Dimethoxy-3-nitrobenzoic acid. A hydrogen-bonded chain structure

2,4,6-Trimethoxybenzoic acid

“…2,3-Dimethoxybenzoic acid forms the normal acid dimer pattern (Bryan & White, 1982a). 2,6-Dimethoxybenzoic acid (Bryan & White, 1982b) and 2,6-dimethoxy-3-nitrobenzoic acid (Frankenbach et al, 1991) form catemers.…”

“…However, in 2,4,6-trimethoxybenzoic acid, we find a syn-anti hydrogen-bond mode and in 2,6-dimethoxybenzoic acid an anti-anti hydrogen-bond mode. So the hypothesis (Frankenbach et al, 1991) of the stabilization of the anti-anti mode by an intramolecular hydrogen bond has to be rejected. More subtle packing effects in the environment of the hydroxyl group have to be considered to give a rational explanation.…”

“…2,3-Dimethoxybenzoic acid forms the normal acid dimer pattern (Bryan & White, 1982a). 2,6-Dimethoxybenzoic acid (Bryan & White, 1982b) and 2,6-dimethoxy-3-nitrobenzoic acid (Frankenbach et al, 1991) form catemers. The carboxyl group of 2,6-dimethoxybenzoic acid exists in an anti conformation, the carboxyl group of 2,6-dimethoxy-3-nitrobenzoic acid in a syn conformation.…”

A theoretical analysis of the structure and electronic properties of 2-nitrophenylcyanate and 2-nitrophenylthiocyanate

“…For example, the nitro group in both 2,4-bis(phenylthio)nitrobenzene (Ha) [ 161 and N, N-dimethyl-2-nitrobenzenesulfenamide (IIb) [17] is essentially coplanar with the respective aromatic ring with an interatomic distance of 2.64 and 2.59 A, respectively, between the sulfur atom and the nearest oxygen atom of the orfho-nitro group. However, while the nitro group in 2,4-dinitroanisole (IIc) [18] is twisted from the ring plane by 20°, that in 2,6-dimethoxy-3-nitrobenzoic acid (IId) [19] is almost coplanar with a twist of only 3.7". Furthermore, the interatomic distances between the methoxyl oxygen and the nearest oxygen atom of the orfho-nitro group in these cases is 2.55 and 2.65 A, respectively, and well within the van der Waals sum.…”

1:1 Crystal complex of 2?,6?-dimethoxyflavone and 2,6-dimethoxybenzoic acid. Relationship of pKa to x-ray hydrogen bond data

“…The carboxyl group in Ib is found in the Z conformation, unlike the carboxyl group in IIb, which exists in the E conformation. 16,17 According to theoretical calculations on formic and acetic acid, 18 Z rotamers are more stable than E rotamers. Single C-O and double C=O bond distances are longer O ( a Numbers in parentheses are estimated standard deviations in the least significant digits.…”