A spectrophotometric method of analysis for the quantitative estimation of cyclopropenoid fatty acids in cottonseed oil based upon the Halphen‐test reaction has been described. Various parameters involved in the reaction have been investigated and two pigment fractions responsible for the characteristic Halphen‐test cherry‐red color have been isolated. The method is applicable to relatively small amts of sample material. The average deviation from the actual cyclopropenoid acid contents as determined by the stepwise HBr titration method was less than ŷ0.02% in both the refined and crude oil series.

IR spectra in the 7.5–25.0 µm region are shown to be unique for polymorphic modifications of long chain saturated fatty acids of even carbon number and also for the individual fatty acids. IR spectra are presented for the A‐, B‐, C‐ and E‐forms of stearic acid and for the C‐form of myristic, palmitic, arachidic and behenic acid and the differences discussed. X‐ray determined crystal long spacings for the A‐, B‐, C‐ and E‐forms of a series of homologous even carbon‐numbered acids are presented and compared with literature values. The formation of the different polymorphic forms are found to be temperature‐concentration related and affected little by polarity of the solvent. Wideline nuclear magnetic resonance second moment values are given for the polymorphic forms of stearic acid.

Twenty compounds, diesters of ethylene glycol, diethylene glycol, or cis-2-butene-l,4-diol, were screened for antimicrobial activity against a grampositive bacterium, Staphylococcus aureus; a gramnegative bacterium, Escherichia coli; a mold, either AspergHlus flavus or A. species; and a yeast, either Candida albicans or Torula species. All of the compounds were inhibitory against two or more of the test organisms, and eight mixed diesters were inhibitory against all four types of organisms. Each of these eight compounds had a benzoate group at one ester function and an acyl group other than benzoyl, mostly fatty acyl groups of 12-22 carbons, at the other.

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The treatment of Sterculia foetida oil with concentrated aqueous HC1 or with HBr in acetic acid results in the addition of one hydrohalogen molecule per cyclopropenoid moiety. Iodine value (I.V.) and infrared absorption measurements indicate that the mechanism parallels that of the polymerization of sterculic acid and involves the formation of four isomeric monounsaturated monohalo moieties.