Postulated scheme forβ crystal structures of mixed palmitic‐stearic triglycerides

Abstract

A structural scheme is proposed forβ phases of the six palmitic‐stearic triglycerides, based on known configurations of tricaprin and 2‐11‐bromoundecanoyl‐1,1′‐dicaprin. The scheme receives some support from short spacing and binary system data.

Structures of mono-unsaturated triacylglycerols. III. The β-2 polymorphs of trans-mono-unsaturated triacylglycerols and related fully saturated triacylglycerols

“…Interestingly, when crystallizing from a melt, the opposite occurs, with melting points of phase(s) that are higher than those of the 0 phase(s). The methyl end-plane configuration in -2 PEP and -2 PSP is of the same type as postulated for mixed palmitic stearic TAGs (Lutton, 1971).…”

“…The pairs, however, are shifted relative to each other along and parallel to the back of the seat. According to Lutton (1971), members of this subgroup are expected to have a h3-3i alignment at the methyl end-plane and PSS indeed shows this alignment (Table 3). LMM, however, has a h2-2i alignment and this is not in line with this postulation.…”

“…Lutton postulated that for mixed-chain-length TAGs, with n and/or n þ 2 C atoms (n even) and similar molecular conformations, the shape of the methyl end-plane should not change because the end-plane is stepped and only the position of the step changes with a difference in chain length (Lutton, 1971(Lutton, , 1972). An hn-ni alignment of chains marks the centres of the three possible step-plane positions.…”

“…An indication for the correctness of the packing can be found by inspection of the methyl end-plane. For example, for PPE a h1-1i alignment at the methyl endplane has been predicted (Lutton, 1971). The PPE model found initially with FOX had an h2-2i alignment, but after rotating the molecule manually in FOX, as described above, the h1-1i alignment was obtained and eventually the final R value of this model became lower than that of the initial h2-2i alignment model.…”

“…Although packing models of saturated mixed-acid TAGs have been proposed (Lutton, 1971(Lutton, , 1972de Jong & van Soest, 1978) and a structural study of the E-chain containing TAGs has been carried out (Elisabettini et al, 1998), the precise influence of replacement of the saturated S-chain by an Echain on their physical properties and packing are still not known.…”