W. Marjit Singh

Crystal packing in some flexible carboxylic acids and esters attached to a naphthalene ring

A structural study of four dicarboxylic acids and four esters attached to a naphthalene ring is presented. (4-Carboxymethoxy-naphthalen-2-yloxy)-acetic acid (1) has a chain structure in the lattice while (6-carboxymethoxy-naphthalen-1-yloxy)-acetic acid (2) and (7-carboxymethoxy-naphthalen-2-yloxy)-acetic acid (3) adopt a sheet-like structure through weak intermolecular interactions, C–H⋯O and C–H⋯π hydrogen bonds. (3-Carboxymethylsulfanyl-1,4-dihydroxy-naphthalen-2-ylsulfanyl)-acetic acid has two symmetrically non-equivalent molecules per unit cell. The asymmetry is caused by weak C–H⋯S interactions. The packing pattern of the methyl esters differs significantly from the parent carboxylic acids and the packing patterns in each case were found to be determined by the C–H⋯O and C–H⋯π interactions.

Synthesis of Mixed Aryl 2,3-Diarylsulphanyl-1,4-naphthoquinones

Abstract The reaction of 2-arylsulphanyl-1,4-napththoquinone with aromatic thiols and sodium dithionate leads to bis-2,3-(arylsulphanyl)naphthalene-1,4-diols in high yield. Corresponding oxidized products, namely 2,3-diarylsulphanyl-1,4-naphthoquinones, are prepared in near quantitative yield by a copper(II)-catalyzed aerial oxidation reaction of bis-2,3-(arylsulphanyl)naphthalene-1,4-diols under mild condition.

Rosolic Acid–Catalyzed Conversion of Thiols to Disulfides

Abstract Various aliphatic and aromatic thiols are converted to the corresponding disulphides by catalytic reaction of 4-[bis-(4-hydroxyphenyl)methylene]-cyclohexa-2,5-dienone in good yield.

Solvatochromicity of 3-hydroxy-4-(1-(2,4-dihydroxyphenyl)-2-hydroxy-2,2-diphenylethylidene)cyclohexa-2,5-dienone for screening of solvents

The quinonic compound 3-hydroxy-4-(1-(2,4-dihydroxyphenyl)-2-hydroxy-2,2-diphenylethylidene)cyclohexa-2,5-dienone (I) is synthesised by the reaction of benzil with 1,3-dihydroxybenzene in basic medium. Solution of this compound shows visibly distinct colour differences in different solvents. From the different absorption maxima of the compound in visible spectra it can be used as an excellent analytical reagent to screen different solvents.