SYNTHESIS OF 2,7-DIMETHYLOCTA-3,5-DIYNE-2,7-DIOL

STEP 1: Place in a 250-m1 conical flask 17.4 g of 2-methylbut-3-yn-2-ol (20 ml, 0.207 mol), 20 ml of methanol, 6 ml of dry pyridine (0.074 mol, CAUTION), 1 g of copper(i) chloride (0.010 mol) and a magnetic following bar. 

STEP 2: Then, with fairly vigorous stirring, bubble oxygen through the solution for 2 hours, at a rate of at least 10 litre/hour. 

STEP 3: The solution becomes warm and rapidly turns dark green. 

STEP 4: Cool the reaction mixture using an ice-water cooling bath and add 10 ml of concentrated hydrochloric acid to neutralise the pyridine and to keep copper salts in solution. 

STEP 5: Add 50 ml of a saturated aqueous sodium chlor­ide solution, cool and filter off the precipitated product. 

STEP 6: Wash the filtered solid with a little ice-cold water to remove any remaining colour and recrys­tallise it from dry toluene. 

STEP 7: This also serves to dry the product if the toluene/ water azetrope is removed by using a Dean and Stark water-separator. 

STEP 8: Cool the toluene solution and filter the colourless crystalline prod­uct; 12 g (70%) of alkynol, m.p. 132-133 °C, is obtained. 

STEP 9: Further recrystallisa­tion from toluene raises the m.p. to 133-133.5 °C.