Verfahren zur Darstellung reiner,geradkettiger Paraffinkohlenwasserstoffe

A normal paraffin having 12-16 carbon atoms is separated from a mixture with other hydrocarbons by separating by distillation a fraction containing more than a specified minimum content of the desired hydrocarbon and subjecting this fraction to fractional crystallization at above - 30 DEG C.; the minimum content specified is by weight, for c -dodecane 60%, for c -tridecane 56%, for c -tetradecane 50%, for c -pentadecane 35% and for c hexadecane 25%. The feed may have been previously concentrated by a urea adduction or molecular sieve adsorption process and the fractionation is conducted to separate a fraction having the desired c -paraffin content, e.g. having a boiling range of less than 8 DEG C. in the case of c -dodecane. Dodecane may be crystallized in bulk, others are crystallized from a solution, e.g. in methylethylketone, dichloroethane, acetone, benzene, toluene or trichloroethylene or mixtures thereof. Crystallization is effected at - 20 DEG to - 30 DEG C. The crystallized c -paraffin may then be washed with solvent in an amount of 1-5 volumes per volume of charge and the filtrate may be recycled.