Question

(1 pts) . PUSL HD Questions 8. TA signature POST LAB QUESTIONS: 1. What major alkene product is produced by dehydrating the following alcohols? a. Cyclohexanol b. 1-Methylcyclohexanol c. 4-Methylcyclohexanol d. 3,3-Dimethylcyclohexanol 2. What is the purpose of the calcium chloride in this experiment? 3. There are three possible isomers when dehydrating 2-methylcyclohexanol. Which do you expect to be the major product and can IR be used to determine which one you have? 4. In this experiment, 1.0 mL of saturated sodium chloride is used to rinse the Hickman still head after the initial distillation. Why is saturated sodium chloride, rather than pure water, used for this procedure and the subsequent washing of the organic layer? Exp 7-5

Answer 1

o when al • It is an . exampl Dehydration of alcohol then alcohol react with brolic acids it trends to ose a molecule of water in order to form alkenes f an elimination reaction • The rates differ for the 1 , 2° and 3° alcohola. 3 carbocation is more stable in tertiary alcohols, hence the rate of dehydration is highest for tertiary alcohols as compared to secondary and primary - alcohols. @ Qehydration of cyclohexanol Hesot 0+, CE Toth (cyclohexand) = ) Z 16+ - H304- ht: 1 - HO+ (cyclohexene) (b) - methylcyclohexanol. C CH3 HO CH3 H2 504 H-methylcycloluxaudf) 1-methylly clohexene methylene wycloluxane . . (major) (Minor) Alehydration of 1-methyl cyclohexanol gius more stable alkene (more highly substituted) as the major product. The major product is 1-methylcyclohexene and methylenecyclohexane is the minor product. CC) 4-methylcyclohexanol CH3 CHз на - > + D + ] сиз muthal welchevene 3-methyl- 1-muthyl- 4-methylcyclohexanol le cyclohexame lyclohexone

4 methylcyclohexene is the major alkene product d) 3,3 - Dimethylcyclohexanol OH -CH3 CH3 CH3 - (3,3-dimethylcyclohexanol Ayclohexanol 1.2 . Paulakeret 1, 2-dimuthylcyclohexene major) isopropyle demeryclopentane (minor)