Sporidesmins. XIX. The diazotization and coupling in acid of p-Nitro- and 2,4-Dinitro-aniline to veratrole or guaiacol: 1H N.M.R. of the products in deuterochloroform and deuteroacetone

p-Nitrobenzenediazonium chloride in conc. HCl coupled to guaiacol (2-methoxyphenol) to give 4-hydroxy-3-methoxy-4'-nitroazobenzene, but did not couple to veratrole (1,2-dimethoxybenzene). 2,4-Dinitroaniline, diazotized in conc. HCl with no urea added, yielded 2-chloro-4,5-dimethoxy- 2',4'-dinitroazobenzene with neat veratrole. However, 2,4-dinitroaniline, diazotized in conc. HCl and then treated with urea, yielded 2-chloro-4-nitrobenzenediazonium chloride which again coupled in acid with guaiacol to give 2-chloro-4'-hydroxy-3'-methoxy-4-nitroazobenzene but not with veratrole in acetic acid. Veratrole added to 2,4-dinitrobenzenediazonium phosphate or trichloroacetate in acid media yielded 3',4'-dimethoxy-2,4-dinitroazobenzene. These 2,4-dinitrobenzenediazonium salts coupled to guaiacol giving 4'-hydroxy-3'-methoxy-2,4-dinitroazobenzene. p-Nitrobenzenediazonium and 2-chloro-4-nitrobenzenediazonium salts in acid gave the Gomberg reaction with veratrole forming the corresponding biphenyls. The 1H n.m.r. spectra of all the products obtained in this investigation and the deshielding effect of deuteroacetone on four of the compounds are discussed. The deuterochloroform spectrum of 4'-hydroxy-3'-methoxy-2,4-dinitroazobenzene at 60 MHz shows an anomalous set of 26 or more lines that are not attributable to a quinone hydrazone structure.