SYNTHESIS OF CYCLOHEXA-1,3-DIENE

STEP 1: In a 100-ml round-bottomed flask place 16.1 g (0.10 mol) of 3-bromocyclo­hexene, 38.7 g of dried, redistilled quinoline and a magnetic stirrer follower. 

STEP 2: Attach to the flask a Claisen still-head fitted with a thermometer and a condenser set for downward distillation. 

STEP 3: Protect the apparatus from atmospheric moisture by a calcium chloride guard-tube attached to the side­arm of the receiver. 

STEP 4: Support the reaction flask in an oil bath which rests on a magnetic stirrer/hotplate, commence stirring rapidly and heat the oil bath to 160-170 °C. 

STEP 5: The cyclohexadiene steadily distils as colourless liquid, b.p. 80­82 °C, over a period of about 30 minutes, yield 5.4 g (68%). 

STEP 6: The product is 99 per cent pure by g.l.c. analysis; use either a 2.7 m column of 10 per cent poly­ethyleneglycol adipate on Chromosorb W held at 60 °C with a flow rate of carrier gas of 40 ml/minute, t_R 2.4 minutes, or, a 1.5 m column of 10 per cent Silicone oil on Chromosorb W held at 6 °C with a flow rate of carrier gas of 40 ml/minute, t_R 1.5 minutes.