R. Garth Pews

Synthesis of 2,6-disubstituted and 2,3,6-trisubstituted anilines

Abstract A number of 2,6-disubstituted and 2,3,6-trisubstituted anilines have been prepared via the selective para dehalogenation of the corresponding anilines. Modification of the substituents on the amino nitrogen demonstrates that the selectivity is derived from steric rather than electronic effects. The effects of the choice of formate hydrogen donor, Pd catalyst, solvent, and temperature upon the efficiency and selectivity of the dehalogenation are discussed.

Pyrrolidine Carboxaldehyde Hydrohalide Catalyzed Halogenations of Aliphatic Aldehydes

Abstract Efficient methods for the direct chlorination or bromination of aliphatic aldehydes to their corresponding α,α-dihalo aldehydes in high yield and purity are unknown. Many approaches have suffered from one or more of the following, formation of byproducts, aldol condensations incomplete conversions and losses through tedious workup procedures. Early investigations have shown that the vapor phase chlorination of aliphatic ketones has produced good yields of 2-chloro ketones,(1) while the vapor phase chlorination of aliphatic aldehydes has resulted in the formation of acid chlorides.(2) One of the first successful acid catalyzed chlorinations of propionaldehyde was reported by Dick(3) who obtained 50–60% yields of 2,2-dichloropropionaldehyde accompanied by aldol condensations and polyhalogenated trioxanes. The reaction was carried out in standardized aqueous mineral acid solutions and the product was isolated by means of a laborious azeotropic distillation. The use of sulfuryl chloride in the presen...

Poly(hydroxy ether sulfonamides). A new class of epoxy‐based thermoplastics

Base-initiated polymerizations of N,′N-dimethyl-1,3-benzenedisulfonamide or other N,′N-dialkyldisulfonamides with various arylene-diglycidyl ethers afford a broad range of poly(hydroxy ether sulfonamides) (2). Polymers 2, which represent a new family of epoxy-based thermoplastics, are moldable, amorphous materials characterized by moderate Tg (58–127°C) and by good barrier to oxygen, reflected by oxygen transmission rates of 0.45–2.89 cc-mil/100 in2-atm (O2)-day at 234 °C and about 60% relative humidity. In addition to a discussion of how structural changes in the backbones of 2 influence their barrier properties, details of the synthesis, thermal analysis and mechanical evaluation of the polymers are described.

A novel synthesis of 2,6-disubstituted and 2,3,6-trisubstituted anilines

Abstract 2,6-Disubstituted and 2,3,6-trisubstituted anilines have been synthesized by a four-step approach involving the selective reduction of a para halogen of the diacetanilide derivatives utilizing a palladium-on-carbon catalyst and formic acid salts as the in situ hydrogen donor.

1,1,1,-trichloro-3-[5-(2,4,6-trifluoropyrimidyl)]-3,4-epoxybutane

Abstract The synthesis of 1,1,1-trichloro-3[5-(2,4,6-trifluoropyrimidyl)]-3-4-epoxybutane has been accomplished in nine steps from diethyl malonate and urea. The epoxide was prepared from the olefinic precursor via oxidation with anhydrous trifluoroperacetic acid in a non-buffered system . Product isolation from trifluoroacetic acid solution demonstrates an unexpected stability of this class of epoxides toward protonic media.

Synthesis of cyclic carbonates by a novel carbonate rearrangement

2,3-Dibromopropyl ethyl carbonate (1) and 1,3-dibromo-2-propyl ethyl carbonate (2) equilibrate at 180° with concomitant formation of 3-bromopropylene carbonate (3) and ethyl bromide (4).

Aromatic fluorine chemistry. Part 5. Preparation of 2,6-difluoroaniline and 1,2-difluorobenzene

Abstract The preparation of 2,6-difluoroaniline and 1,2-difluorobenzene from 1,2,3- trichlorobenzene is described. An isomeric mixture of 1-chloro-2,3-difluorobenzene and 2-chloro-1,3-difluorobenzene is obtained from KF exchange on 1,2,3- trichlorobenzene. Selective dechlorination of 1-chloro-2,3-difluorobenzene with H2 and Pd/C catalyst gives 1,2-difluorobenzene. 2,6-Difluoroaniline is obtained via ammonolysis of 2-chloro-1,3-difluorobenzene.

A practical synthesis of 2-methoxy-6-trifluoromethylaniline

Abstract A practical synthesis of 2-methoxy-6-trifluoromethylaniline is described via halogenation, nitration and reduction of 3-trifluoromethylanisole

Novel synthesis of benzotrihalides: the pyrolysis of phenyl trihalogenoacetates

Pyrolysis of 4-chlorophenyl trichloroacetate (I) at 500 °C yields 4-chlorobenzotrichloride (II) and some 1,4-dichlorobenzene (III) as by-product; the corresponding trifluoroacetate is converted into 4-chlorobenzotrifluoride.

Bromide catalysis in the preparation of benzylidyne trichlorides via photochlorination

Bromine catalyses the photochlorination of substituted toluenes to benzylidyne trichlorides.