Abstract
Levo-2,3-Butanediol is more effective than glycerol and less effective than ethylene glycol as a freezing point depressant for water. The considerable discrepancy that is reported between observed freezing points and values calculated from Raoult's law for solutions of these chemicals is attributed to hydration. The antifreeze property of levo-2,3-butanediol is not impaired by prolonged refluxing or by use in automobile cooling systems. The viscosity of 50 to 60% solutions is considerably greater than that of 50 to 60% ethylene glycol and is slightly greater than that of 50 to 60% glycerol at 20 °C., the differences in viscosity between these solutions being magnified by low temperatures. Kinematic viscosity data are presented for levo-2,3-butanediol solutions at concentration intervals of 10% over the greater part of the liquid range.The comparatively low surface tension of levo-2,3-butanediol solutions indicates a possible need for precautionary measures against creeping and foaming. Metallic corrosion is not greater than with water, barring excessive contamination with acetates. levo-2,3-Butanediol and ethylene glycol are judged equally satisfactory with respect to heat capacity, flash point, expansion on solidification and heating, and effects on metal finishes and rubber. Density of levo-2,3-butanediol solutions cannot be used as a measure of freezing point protection. The mixtures of 2,3-butanediol isomers obtained with Aerobacter aerogenes, Aeromonas hydrophila, and Bacillus subtilis are lacking in antifreeze properties because of their high content of the meso-isomer.

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