Capillary gas chromatography of C 5C 13 branched alkynes on squalane and liquid crystal stationary phases

Abstract

The retention behaviour of 49 C 5C 13 branched alkynes, including all 36 methyl- and dimethylalkynes up to C 8, were studied by capillary gas chromatography on squalane and 4- n-pentylacetophenone-O-(4- n-pentyloxybenzoyl)oxime liquid crystal as stationary phases. An additive method of retention increments based on the analogy of retention in homologous series of the corresponding branched alkynes and alkenes, showing an average precision of 1 index unit, was suggested for the calculation of retention indices of branched alkynes and alkynes with a methyl group on the α-carbon in particular. Both regularities and anomalies in the retention behaviour of branched alkynes are discussed with regard to retention—structures correlations. The advantages of liquid crystals as stationary phases for the separation of isomers with close physico-chemical characteristics are pointed out.