vulcanization by polynitro compounds remains unchanged; Bruni and Geiger showed that the addition of nitrosobenzene to rubber involves no "net consumption of carbon to carbon unsaturation. If the same type of condensation occurs with the polynitroso compound, which we have considered to be formed from the polynitro compound, no change in unsaturation should be expected2.The foregoing hypothesis resembles only superficially one proposed by Ostromislensky (S3), who attempted to prove that polynitrobenzene vulcanization entails transfer of oxygen to the rubber:
1. The densities of liquid pentene-1 under its vapor pressure were determined from 0 to 50°.2. The vapor pressures of pentene-1 were determined from 0 to 200°;3. Calculated heats of vaporization are reported at 0 and 30.07°.
Observations by Aylward and Rao that hydrazine is a reducing agent for a number of unsaturated fatty acids were extended. The hydrazine reaction on linolenic acid was followed by periodic sampling until methyl esters prepared from the reduced acids had an iodine value of 162. These esters were shown by countercurrent distribution to consist of 26% triene, 43% diene, 26% monoene, and 5% stearate and by infrared analysis to contain notrans bonds.
Oxidation of the separated monoene and diene fractions by permanganate‐periodate mixtures and gas chromatography of the dibasic acids showed that the double bonds were in the original 9, 12, and 15 positions and that the double bonds farthest from the carboxyl were reduced at a slightly faster rate. Gas chromatography of the monoene fraction indicated three components that were identified in the order of elution from the column as 9, 12, and 15 monoenes; in the diene fraction three components were identified in the order of elution as 9,12; 9,15; and 12,15 dienes. After alkali isomerization of this diene fraction, the conjugated material was reacted with maleic anhydride; the unreacted 9,15 diene isomer was separated by distillation.
SummaryAcetonitrile‐pentane‐hexane makes a desirable solvent system for preparation of pure methyl esters because of its immiscibility, selectivity toward unsaturation, low boiling point, stability, and ease of recovery. Since separated esters are removed from the apparatus dissolved in the pentane‐hexane layer, successive batches may be fractionated without removing the acetonitrile layer from the instrument. Applications have been illustrated for the preparation of methyl linolenate from an 85% linolenate concentrate, methyl linoleate from safflower esters, and methyl arachidonate from pig liver lipids.This procedure provides a source of “natural” fatty acids with the double bond configuration unchanged, in contrast to those from the conventional bromination‐debromination process. Automation of the process is completed by use of a recording refractometer which monitors concentration of solutions issuing from the extractor. Resolutions to be anticipated with lesser numbers of extraction tubes than 200 are calculated for an equal mixture of linoleate and linolenate.
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