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 Preparation of Ethyl hydrogen sebacate
  • Preparation of Ethyl hydrogen sebacate
  • Ethyl hydrogen sebacate (CAS NO.: ), which is also known as monoethyl sebacate, could be produced through the following synthetic routes.

    Preparation of Ethyl hydrogen sebacate

    In a 1-l. modified Claisen flask, the side arm of which is corked, is placed a mixture of 202 g. (1 mole) of sebacic acid, 150 g. (0.58 mole) of diethyl sebacate, 50 cc. of di-n-butyl ether, and 30 g. (25 cc.) of concentrated hydrochloric acid (sp. gr. 1.19). A reflux condenser is connected to the top of the distilling flask.

    The flask is heated in a Wood's metal bath at 160–170° until the mixture is completely homogeneous. The temperature of the bath is then lowered to 120–130°, and 60 cc. (1 mole) of 95 per cent ethyl alcohol is added to the solution through the condenser. The mixture is allowed to reflux for two hours. At the end of this period an additional 20-cc. portion of ethyl alcohol is poured into the solution and refluxing is continued for two hours longer.

    The Wood's metal bath is allowed to cool to about 75° and the reaction mixture is subjected to distillation under reduced pressure, using a water pump. The temperature of the bath is increased slowly and distillation is continued, with a water pump, until the bath reaches a temperature of about 125°. The bath is again cooled to 75–80° and the distillation is continued at lower pressure, using an oil pump.

    The first fractions consist of a little alcohol, water, and n-butyl ether. The next fraction is ethyl sebacate, b.p. 156–158° at 6 mm.. Ethyl hydrogen sebacate is collected at 183–187° at 6 mm. The product melts at 34–36° and weighs 114–124 g. (50–54 per cent of the calculated amount, based on the sebacic acid used). Refractionation of the fore-run (b.p. 175–183°/6 mm.) and after-run (b.p. 187–195°/6 mm.) gives an additional 24–26 g. of pure monoester. The total yield is 138–150 g. (60–65 per cent of the theoretical amount).


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