Variation of unit-cell dimensions of a crystal form of long normal chain carboxylic acids

Abstract

This work was carried out in connexion with crystalstructure investiggtions of long normal chain carboxylic acids. Vand, Aitken & Campbell (1949) found tha t all the unit-cell dimensions of silver soaps changed with chain length. In order to find the behaviour of the unit-cell dimensions of a crystal form of long normal chain carboxylic acids the unit cells of form C of several acids with an even number of carbon atoms were determined, using powder methods. The crystal structure of form C of lauric acid has been determined by Vand, Morley & Lomer (1951). The unit cell is monoclinic with four molecules in the cell. The hydrocarbon chains have the orthorhombic packing determined by Bunn (1939) and Vainshtein & Pinsker (1950). Unitcell determinations of this form have been made by Thibaud & Dupr4 la Tour 0932) (palmitic acid) and by Trillat & v. Hirsch (1932) (stearic acid).