Methylcyclohexane ring-contraction: A sensitive solid acidity and shape selectivity probe reaction.

In this paper we describe the utility of an acid-catalyzed isomerization reaction, specifically, ring-contraction of methylcyclohexane to an isomeric mixture of alkylcyclopentanes as a tool for characterizing the acidic properties of a wide range of platinum-loaded solid acids. Methylcyclohexane isomerization is particularly useful as a solid acidity probe reaction since it is a simple molecule containing one six-membered ring and a single methyl group substituent. As a solid acidity probe molecule methylcyclohexane has a number of advantages over cyclohexane.

Complete nucleotide sequence of the Sulfolobus islandicus multicopy plasmid pRN1.

The complete sequence of the 5350-bp plasmid pRN1 from the crenarchaeote Sulfolobus islandicus has been determined. This plasmid is the first to be sequenced from this group of thermoacidophilic archaebacteria (Archaea) and its high copy number and wide host range make it a good candidate for a cloning vector. pRN1 contains several open reading frames, including one that spans over half the plasmid and has significant similarity to the helicase domain of viral primase proteins.