Summary
Existing ultraviolet spectrophotometric methods have been modified for application primarily to the detection and estimation of low proportions of conjugated and nonconjugated unsaturated constituents in fats, oils, and soaps. The method is applicable also to fatty materials having high proportions of these constituents.
Modifications include corrections for absorption by interfering substances, use of alkaline glycerol as an isomerization medium in the analytical procedure, and correction of absorption data on the isomerized product for absorption by conjugated constituents in the material before isomerization.
The presence of small proportions of highly unsaturated conjugated and nonconjugated compounds is established in lards, tallows, tallow soaps, and highly purified esters and acids. Tall oil fatty acids are shown to contain approximately 10% of conjugated diene acids and a small amount of linolenic acid.
SynopsisThis paper describes the preparation of the first members of a new series of polysiloxanes characterized by having m-carborane nuclei in the backbone of the polymers. Although neither hydrolysis of 1,7-bis( chlorodialkylsilyl)-mcarborane monomers nor catalytic dehydration of the corresponding dihydroxy compounds would proceed to give the type of polysiloxanes desired, the polymers were readily prepared by the ferric chloridecatalyzed elimination of an alkyl halide from equimolar mixtures of dichloro-and dialkoxysilanes. This t,echnique allowed the systematic introduction of dialkylsiloxy groups between m-carborane nuclei. Characterization of the polymers is described as well as differential scanning calorimetry studies which show the prime members of the series to be thermally stable to 500°C. and oxidatively stable to about 350OC.
CHICHI CH3
When the carbons of carborane participate in exocyclic rings the thermal rearrangement of the ortho carborane nucleus to the meta configuration is opposed. These molecules as a whole therefore resist degradation at elevated temperature. Chemically these cyclics are stable under acid conditions but the silicon-carborane carbon bond is attacked by bases. Additional types of cyclic silazanes are reported and reactions of some functional groups at the silicon atoms are described.
Results and DiscussionConsiderable evidence of both a chemical and a physical nature has been amassed to establish the skeletal structure of 1,2-dicarbaclovodod ecaborane (12) (carborane) as an icosahedron of ten boron atoms and two atoms in which the carbon atoms are in nearest proximity or ortho to each other,1-6 although other structures have been postulated.
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