- Use the same technique as detailed for HEX-1-YNE(butylacetylene) but with a 3-litre three-necked flask.
- Charge the flask with 1.5 litres of liquid ammonia.
- Prepare the sodamide using 0.7 g of iron(m) nitrate and 2 g of sodium, followed by 46 g (total 2.1 mol) of sodium, and convert it into a solution of sodium acetylide as before.
- Add, with stirring, a solution of 196 g (206 ml, 2 mol) of dry, redistilled cyclohexanone (1) in 256 ml of dry ether during 1 hour and continue the stirring for a further 2 hours.
- Decompose the sodium derivative of the product by the gradual addition of a slight excess (118 g) of powdered ammonium chlorchloride.
- Allow to stand overnight, preferably with stirring, by which time all the ammonia will have evaporated.
- Extract the residue repeatedly with ether, i.e. until all the alkynol has been separated from the inorganic material (2).
- Wash the ethereal extract successively with water, dilute sulphuric acid and sodium hydrogen carbonate solution, dry with magnesium sulphate and distil.
- Collect the 1-ethynylcyclohexanol at 83 °C/20 mmHg (3); the yield is 210 g (85%).
Notes to keep in mind:
1. Dry the cyclohexanone over excess of anhydrous calcium chloride before distillation.2. A continuous ether extractor is recommended.
3. The product has m.p. c. 25 °C, but the m.p. depends upon the purity of the cyclohexanone and the efficiency of the distillation. Pure 1-ethynylcyclohexanol has m.p. 32 °C.
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