Royston M. Roberts

Low-temperature pyrolysis of Texas lignite, basic extracts and some related model compounds

Abstract Low-temperature (400 °C) pyrolysis of Texas lignite produced volatile products typical of coal tars, with tar evolution beginning at about 300 °C. n -Alkanes up to about C 30 were observed among the products and these were accompanied by smaller but significant amounts of 1 -alkenes. Similar pyrolyses were performed on pyridine extracts and sodium hydroxide extracts of lignite. The alkanes and alkenes were seen among the pyrolysis products from the pyridine extracts and from the residual lignite from both types of extractions, but they were not seen among the pyrolysis products from the sodium hydroxide extracts. Pyrolyses of some model compounds suggested that dealkylation of alkyl-substituted arenes can be significant at 400 °C and can account for the production of the alkanes and alkenes from the lignite.

Aluminium bromide catalysed transalkylations of a Texas lignite coal

Abstract Texas lignite coal was treated at a variety of reaction times and temperatures with water-activated AlBr 3 in the presence of either m -xylene or diphenyl ether. Reactions with m -xylene resulted in increases in coal weights, probably due to incorporation of xylene into the coal structure, whereas reactions with diphenyl ether resulted in weight losses in the treated coal. The solubility in pyridine of the coal recovered from these reactions was increased significantly, reaching a maximum of 50% in one reaction with diphenyl ether. Suggestions are made for processes that may explain both the weight increases and the greater pyridine solubility. Support for the occurrence of transalkylation of alkyl groups from lignite to diphenyl ether was provided by g.c.-m.s. analysis of an ether extract in which diphenyl ether molecules substituted with C 1 –C 13 alkyl groups could be identified. Also of interest was the observation of the compound phenoxathin among the products of transalkylation.

New friedel-crafts chemistry—XX : Reported lack of rearrangement in alkylations with primary alcohols and aluminum chloride

Abstract Aluminum chloride-catalyzed alkylations of benzene with 1-propanol, cyclobutylcarbinol, cyclopentylcarbinol, and cyclohexylcarbinol have been reported to take place without any rearrangement of the alkylating species. We have now reinvestigated these alkylations and have found that in every case isomerizations occur which are consistent with expected rearrangements of intermediate carbonium ions or equivalent complexes. The relative amounts of n-propyl- and isopropylbenzene obtained from 1-propanol depend on the severity of the conditions; long heating results in disappearance of isopropylbenzene from the liquid reaction mixture owing to much more rapid dealkylation of this isomer than of n-propylbenzene. The major product from cyclobutylcarbinol is cyclopentylbenzene; from cyclopentylcarbinol, cyclohexylbenzene; and from cyclohexylcarbinol, a mixture of isomeric methylphenylcyclohexanes. These reactions are now shown to be consistent in mechanism with other aluminum chloride-catalyzed alkylations with primary alkyl derivatives.Abstract Aluminum chloride-catalyzed alkylations of benzene with 1-propanol, cyclobutylcarbinol, cyclopentylcarbinol, and cyclohexylcarbinol have been reported to take place without any rearrangement of the alkylating species. We have now reinvestigated these alkylations and have found that in every case isomerizations occur which are consistent with expected rearrangements of intermediate carbonium ions or equivalent complexes. The relative amounts of n -propyl- and isopropylbenzene obtained from 1-propanol depend on the severity of the conditions; long heating results in disappearance of isopropylbenzene from the liquid reaction mixture owing to much more rapid dealkylation of this isomer than of n-propylbenzene. The major product from cyclobutylcarbinol is cyclopentylbenzene; from cyclopentylcarbinol, cyclohexylbenzene; and from cyclohexylcarbinol, a mixture of isomeric methylphenylcyclohexanes. These reactions are now shown to be consistent in mechanism with other aluminum chloride-catalyzed alkylations with primary alkyl derivatives.

ACYLATION/CYCLIALKYLATION OF ALLYLBENZENE : A NOVEL SYNTHESIS OF 4-BENZYL-2-TETRALONE

Abstract A novel synthesis of 4-benzyl-2-tetralone from allylbenzene and phenylacetyl chloride is described.

New Friedel-Crafts chemistry—XXI : Alkylations with isobutyl alcohol and isobutyl chloride under “drastic” conditions

Alkylations of benzene with isobutyl alcohol and isobutyl chloride using massive amounts of aluminum chloride gave low yields of butylbenzene mixtures composed of mainly t-butylbenzene, but also containing minor amounts of isobutyl- and sec-butylbenzene. Alkylations with t-butyl chloride under similar alkylation conditions also yielded isobutyl- and sec-butylbenzene. It is shown that reasonable explanations of these results can be given without resort to the ad hoc theory that drastic experimental conditions reverse the usual order of isomerizations.