X-ray study of primary long chain alkylammonium halides

Abstract

Primary normal alkylammonium halides crystallize in a preferred crystallographic orientation, forming single or twinned layers. The basal spacings are related to the number of carbon atoms within the homologous series, and are doubled in the twin layers. The orientation of the hydrocarbon chains between the ionic heads is discussed.

Polymorphism in n-Alkylammonium Halides. A Wide Line Nuclear Magnetic Resonance Study of the Chlorides C11—C15

“…If the longer chain compounds are heated, to remove solvent for instance, they will return to a different crystal structure upon cooling to room temperature. The reported X-ray results for n-dodecyclammonium chloride and bromide suggest that this change may involve a doubling of the (001) spacing (7,8 Thus we believe that two different crystal structures can exist for those members of the series which have transitions sufficiently far above room temperature. One form can be obtained by crystallization below the lowest transition and the other by heating the first above the transition.…”

“…The reported X-ray structural studies are limited almost entirely to room temperature measurements of the (001) long spacings (4)(5)(6)(7)(8), and only n-propyl-and npentylamnioniu~i~ chlorides (9,10) and t1-dodecylamrnoni~~m bromide (7) appear to have been s t~~d i e d in any greater detail. In general the chlorides are tetragonal up to a chain length of about 10 carbon atoms and either monoclinic (C,,,C,,,C,,,C,, ) or orthorhombic (C, ,,C,,) thcreafter.…”

A differential scanning calorimetric study of phase transitions in polysubstitutedn-alkylammonium halides

“…For example, the quaternary salts are excellent cationic detergents when dissolved in hydrocarbons; their concentrated solutions are known as liquid membranes (and are believed to control a large number of biological processes, with their bioactivity being a function of the structure of the solute); and they are pharmacologically active substances [1]. The secondary salts are widely used in solvent extraction processes in general and in the extraction of fused salts in particular [2].During the course of these investigations, attempts have been made to correlate the properties of these materials in solution and in the molten state with the structure in the solid state [2,3]. However, the existence of several solid-solid transitions in these compounds have been previously established [4][5][6][7].…”