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The effect of temperature on the course and extent of reactions involving Grignard reagents has rarely been studied below -30°. The outstanding example of a successful result at extremely low temperatures is the formation of acids by treatment of Grignard reagents with solid carbon dioxide (1). Recently it has been shown that at about -70°acetic anhydride reacts with various Grignard reagents to form the corresponding methyl ketones in high yield (2).In this paper we report on further studies of this reaction technique and demonstrate the reason for its success.Effect of temperature. We have studied the reaction which takes place when a solution of butylmagnesium bromide is added to a solution of acetic anhydride in ether at different temperatures. It was found that from the reflux temperature of ether to about -40°the yield of ketone remained almost constant at 50%.2 However, the yield increased rather sharply on further cooling and reached 79% near -70°. One experiment indicated that by going to lower temperatures higher yields might be obtained. However, because of the inconvenience we did not explore this region further. This temperature effect seemed to be about the same in the reaction of i-butylmagnesium chloride with acetic anhydride and of phenylmagnesium bromide with benzoic anhydride. At -70°each gave ketone in about 80% yield but at 0°the yields were about 50%. We did not investigate these cases further but assumed that they were approximately the same as for the case of n-butylmagnesium bromide and acetic anhydride. Our results are summarized in Table I.

Summary Variations between commercial hexanes from different sources and boiling ranges of some solvents are sufficiently large to require specific data on vapor pressures for the solvent or solvent fraction in a miscella. Pressure‐concentration‐temperature relations, experimentally determined for three commercial hexanes and a heptane in soybean oil, have been correlated and presented graphically as a single set of curves, characteristic of n‐hexane. An example of a method is given by which these curves can be used to obtain specific data for any hexane solvent. A variation of ±5°F. in solvent boiling point is shown to cause a ±6% change in miscella concentration which can be corrected by a change of ±8°F. in operating temperature. This effect is due to a ± 7.5% variation in miscella vapor pressure, when the solvent boiling point varies by ±5°F., which is sufficiently greater than the uncertainty of pressures read from the correlation, about ±2%, to require consideration in design and operation of solvent recovery equipment.