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The polymorphism of odd and even saturated single acid triglycerides, C 8 –C 22
Author(s) -
Lutton E. S.,
Fehl A. J.
Publication year - 1970
Publication title -
lipids
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.601
H-Index - 120
eISSN - 1558-9307
pISSN - 0024-4201
DOI - 10.1007/bf02531101
Subject(s) - glyceride , alternation (linguistics) , polymorphism (computer science) , crystallography , chemistry , diffraction , fatty acid , organic chemistry , physics , genotype , philosophy , linguistics , biochemistry , optics , gene
The polymorphism of single fatty acid odd triglycerides, C 11 through C 17 has been reinvestigated, with extension of the study to C 9 , C 19 and C 21 . With study of the even glycerides C 8 , C 20 and C 22 it has been possible to review the whole series (odd and even) C 8 through C 22 . The odd glycerides resemble the even in showing three distinct melting levels. Lowest melting forms are α. Stable forms are β except for C 9 and C 11 which show a different structure type. Intermediate melting β′ forms of odd glycerides are substantially more stable than their even counterparts as well illustrated by differential thermal analysis. There are no vitreous forms. Alternation in mp (between odd and even) is confirmed for stable phases and nonalternation for α and (within experimental error) for β′. Both β′ and β long spacings show alternation but not α. Alternation is evident in the short spacings of β′ and β forms. While short spacings of β′ forms of even triglycerides are much alike especially for C 14 through C 22 , those of odd glycerides show a fortuitous 4‐carbon cycle. This appears to involve no significant structural variation as chain length increases but simply an approximate 4‐carbon cycle of variation in diffraction details derived from the presumed unvarying 0 ⊥ type subcell structure.