. Practical methods of organic chemistry . eceiver, besides some al-cohol, water, and acetal. Ifuncondensed vapours of thealdehyde escape from the re-ceiver, the mixture is admittedto the flask more slowly. Onthe other hand, if boiling is not caused by the flowing in of themixture, the reaction is assisted by heating with a small all of the mixture has been added, the flask is heated for ashort time by a flame, until boiling begins. Since the aldehyde cannot be obtained easily from the reaction-products by fractional distillation, it is first converted into alde-hyde-ammonia, which
. Practical methods of organic chemistry . eceiver, besides some al-cohol, water, and acetal. Ifuncondensed vapours of thealdehyde escape from the re-ceiver, the mixture is admittedto the flask more slowly. Onthe other hand, if boiling is not caused by the flowing in of themixture, the reaction is assisted by heating with a small all of the mixture has been added, the flask is heated for ashort time by a flame, until boiling begins. Since the aldehyde cannot be obtained easily from the reaction-products by fractional distillation, it is first converted into alde-hyde-ammonia, which, on proper treatment, readily yields thepure aldehyde. The apparatus for this purpose is arranged as follows : A smallflask to contain the aldehyde, placed on a wire gauze, is connectedwith a moderately large reflux condenser. Into the upper endof the condenser is placed a cork bearing a rj_-shaped glass tube,which is connected with two wash-bottles, each containing 50 dried ether. After the condenser has been filled with water at. Fig. 66. ALIPHATIC SERIES I45 300 (the lower side-tube of the condenser is closed with rubbertubing and a pinch-cock), the crude aldehyde is heated for 5-10minutes to gentle boiling, and the aldehyde that is not condensedpasses over, and is absorbed by the ether. Should the ether beginto ascend in the connecting tube, the flame must be somewhatincreased immediately. To obtain aldehyde-ammonia, a currentof dry ammonia (see page 348) is conducted, with the aid of awide adapter or funnel (Fig. 66), into the ethereal solution con-tained in a beaker surrounded by a freezing mixture of ice and salt,until the liquid smells strongly of it. After an hour, the aldehyde-ammonia which has separated out is scraped from the sides of thevessel and adapter with a spatula or knife, filtered with suction,washed with a little ether, and then allowed to dry on filter-paperin a desiccator. Yield, about 30 grammes. In order to obtain pure aldehyde, 10 grammes of a
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