Organic Lab (I) Expt 9: Preparation of an Alkene

The reaction of cyclohexanol with sulfuric acid to form cyclohexene is

• a hydration reaction

• a substitution reaction

• an addition reaction

• an elimination reaction

When using saturated sodium bicarbonate aqueous solution to wash the organic layer, the gas generated is

• carbon dioxide

• water vapor

• sulfur dioxide

• carbon monoxide

In previous experiments (e.g. experiment 1), we diluted the crude mixture with organic solvent and then performed extraction, followed by removal of organic solvent under reduced pressure to obtain the products.

However, similar steps will not be performed in this experiment and the crude mixture is extracted without dilution. It is because

• we want to save energy

• we want to reduce the use of organic solvent

• cyclohexene cannot be dissolved in other organic solvents

• the boiling point of cyclohexene is too low and it will be removed by the rotary evaporator

Concerning the step for extraction, which of the following is a correct statement?

• A uniform emulsion will form.

• The organic layer and aqueous layer will mix together to form one uniform phase.

• The organic layer will be the bottom layer while the aqueous layer will be the top layer.

• The organic layer will be the top layer while the aqueous layer will be the bottom layer.

In the preparation of cyclohexene from cyclohexanol by sulfuric acid catalyst, the first step of the reaction mechanism involves

• deprotonation of the hydroxyl group on cyclohexanol

• protonation of the hydroxyl group on cyclohexanol

• protonation of the carbon-carbon double bond on cyclohexene

• breakdown of carbon-oxygen bond in cyclohexanol to form a carbocation and hydroxide anion