Reaction Oxidation of a Primary Alcohol to an Aldehyde

Since the aldehyde cannot be obtained easily from the reaction-products by fractional distillation, it is first converted into aldehyde-ammonia, which, on proper treatment, readily yields the pure aldehyde. 

The apparatus for this purpose is arranged as follows A- small flask to contain the aldehyde, placed on a wire gauze, is connected with a moderately large reflux condenser. Into the upper end of the condenser is placed a cork bearing a rL-shaped glass tube, which is connected with two wash-bottles, each containing 50 c.c. of dried ether. After the condenser has been filled with water at 

In order to obtain pure aldehyde, 10 grammes of aldehyde-ammonia are dissolved in 10 grammes of water, treated with a cooled mixture of 15 grammes of concentrated sulphuric acid and 20 grammes of water, and heated on the water-bath. Since aldehyde has a low boiling-point (210), the receiver is connected with the condenser by a cork, and well cooled with ice and salt. 

Aldehydes can be obtained by the use of the general reaction, which in many cases serves as a method of preparation, of extracting two hydrogen atoms from a primary alcohol by oxidation. 

The name of the class of compounds is derived from this action Aldehyde = Al(cohol)dehyd (rogenatum). As an oxidising agent in the above case, chromic acid is the most suitable in the form of potassium, or sodium dichromate in the presence of sulphuric add  

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