of the borohydride before reaction with the aldehyde, and the error can be eliminated if the solvent is made Q.01AÍ in sodium hydroxide. The n-alkyl aldehydes react rapidly enough that the hydrolysis is negligible even in the absence of base. In each case where sodium hydroxide was used, a sample of the aldehyde was allowed to stand in the Q.OlAf base at 45°C. for 30 minutes before titration, and in no case were the titration results significantly different from those in which the aldehyde was titrated immediately.Furfural and o-me thoxy benzaldehyde, even when titrated in base at 45°C ., gave high results because of the slowness of the borohydride reduction.Cinnamaldehyde, p-hydroxybenzaldehyde, p-dimethylaminobenzaldehyde, vanillin, and anisaldehyde were even more unreactive and could not be determined by this titration procedure.Presumably, any of the aldehydes listed by Jensen (1) as having a rate constant less than 40 liter mole-1 minute-1 would also be too unreactive for accurate titration, Formaldehyde, hemiacetalforming aldoses, and other compounds which do not show the characteristic carbonyl absorption peak in water can not be determined by this method since no change in absorbance can be detected.Peroxides and some ketones will cause serious interference in the method. Ketones in general are much less reactive toward borohydride than are aldehydes but certain ketones such as acetone and cyclohexanone are readily reduced. Less reactive ketones such as methyl hexyl ketone or acetophenone will not cause interference unless their concentration greatly exceeds that of the aldehyde being determined.Compounds containing acidic hydrogen atoms will decompose the borohydride titrant, but these may be neutralized before titration is initiated.Functional groups which are not reduced" by borohydride in this medium include anhydrides, esters, amides, imides, acetals, nitriles, halides, and carbon-carbon double bonds. LITERATURE CITED(1) Jensen, E. ., "A Study on Sodium Borohydride," Nyt Nordisk Forlay

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