Ross W. Millar

A novel method for the nitration of deactivated aromatic compounds

Novel nitration systems comprising nitric acid, trifluoroacetic anhydride and zeolite Hβ, with or without acetic anhydride, are described. The system having no acetic anhydride is more active and readily nitrates deactivated substrates such as nitrobenzene, benzonitrile, benzoic acid or 4-nitrotoluene to give predominantly the product substituted meta to the deactivating group.The system incorporating acetic anhydride is more moderate in activity, and nitrates moderately deactivated systems such as halogenobenzenes quantitatively within two hours at ice–salt bath temperature, and provides very high selectivity for the para-nitrated product. This system also nitrates 2-nitrotoluene to give high selectivity for 2,4-dinitrotoluene production. Furthermore, the system can be used for direct double nitration of toluene and gives a 92% yield of 2,4-dinitrotoluene with a 2,4-∶2,6-dinitrotoluene ratio of 25∶1. Even greater selectivity (96% yield and 70∶1 selectivity) can be achieved in the latter reaction by conducting the reaction in one flask but in two stages, with trifluoroacetic anhydride added only in the second stage. p

Preparation of N-aryl-S,S-diphenylsulfilimines by nucleophilic attack of N-lithio-S,S-diphenylsulfilimine on aromatic compounds

Abstract N-Aryl-S,S-diphenylsulfilimines with unusual substitution patterns have been prepared by reacting the novel nitrogen nucleophile N-lithio-S,S-diphenylsulfilimine with a range of activated aromatic substrates. N-Lithio-S,S-diphenylsulfilimine is not only able to displace chloro groups in conventional aromatic nucleophilic substitution reactions, but also, unlike S,S-diphenylsulfilimine itself, can attack at hydrogen-bearing positions in ‘vicarious’ aromatic nucleophilic substitutions of hydrogen.

Preparation of a Series of N-Aryl-S,S-diphenylsulfilimines by Nucleophilic Attack of S,S-Diphenyl-sulfilimine on Activated Halogenoaromatic Compounds

Some N-aryl-S,S-diphenylsulfilimines, most of which are novel compounds, are prepared and characterised, using a method based on nucleophilic attack of diphenylsulfilimine on activated aryl halides, especially polyhalogenated heterocyclic aromatic compounds.

Evidence for the formation of a guanidinium ylide

Evidence is presented for the formation fo a guanidinium fluorenylide which reacts with nitrosobenzene to give N-fluoren-9-ylideneaniline N-oxide.