Organic 2 Review Problem 91

Organic 2 Review Problem 91 - PREPARATIONS 75 50 ml. water...

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PREPARATIONS 75 50 ml. water contained in a small beaker, add 40 ml. (32-5 g.) of ethanol, and then place the well-stirred mixture in the drop- ping-funnel. Ensure that a rapid stream of cold water is passing through the condenser and that the adaptor A dips into a ioo ml. conical flask which is surrounded with ice-water. Now heat the dilute acid in the flask until it starts to boil gently, and then remove the flame and run the dichromate solution very slowly into the flask. Directly the ethanolic dichromate solution enters the hot acid, a vigorous reaction occurs, and a mixture of acetalde- hyde and water, containing a little acetic acid, begins to distil over: meanwhile the reaction mixture becomes green owing to reduction of the dichromate. The addition of the dichromate solution should take about 20 minutes: towards the end of this time it will be necessary to replace the flame under the flask to maintain gentle boiling. When the addition of the dichromate solution is complete, a moderately concentrated aqueous solution
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