preparation of acetylene
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Acetylene, also called Ethyne, the simplest and best-known member of the hydrocarbon series containing one or more pairs of carbon atoms linked by triple bonds, called the acetylenic series, or alkynes. It is a colourless, inflammable gas widely used as a fuel in oxyacetylene welding and cutting of metals and as raw material in the synthesis of many organic chemicals and plastics; its chemical formula is C2H2.
15 g of calcium carbide are place in a 150 ml distilling-flask. A dropping funnel and a glass tube are fitted to the top of the flask. The glass tube is connected with a wash-bottle containing 10% aqueous copper sulfate solution. The tall dropping funnel is required in order to give a sufficient “head” of water in the funnel to force the acetylene to pass through the wash-bottle. Additionally a delivery-tube is fitted to the wash-bottle, which is used for the collecting acetylene under water or delivering the gas for required experiment. The dropping-funnel is filled with water, and added to the flask drop-wise. By contacting with calcium carbide acetylene is at once generated, and on passing through the copper sulfate solution is freed from hydrogen sulfide, or other impurities. In the beginning of experiment the acetylene passes through the apparatus until all the air is expelled. The acetylene as is collected under water or directly used for an experiment.
Preparation of acetylene from 1,2-dibromoethane and potassium hydroxide
Preparation of acetylene from 1,2-dibromoethane and potassium hydroxide
Preparation of acetylene from 1,2-dibromoethane and potassium hydroxide.
F is a wide-necked 250 ml bolt-head flask, to which is fitted a double-surface reflux water-condenser C and the dropping funnel D. From the top of C, a delivery-tube leads down to the pneumatic trough T, where the gas can be collected in jars in the usual way. 100 ml of rectified ethanol and 25 g of powdered potassium hydroxide are placed in the flask F. The mixture is gently boiled under reflux until the potassium hydroxide is almost entirely dissolved. 15 ml (or 33 g) of 1,2-dibromoethane is place in the dropping funnel D, and added drop-wise into the boiling solution of potassium hydroxide in ethanol. A rapid reaction occurs, acetylene being generated and potassium bromide precipitated. Generated acetylene is passes through the apparatus until all the air is expelled. Then acetylene is collected under water or directly used for an experiment.
Practical organic chemistry, by F. G. Mann, 86-88, 1960
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