Alcohols

Question 1

What 3 structures are found in alcohols

Answer 1

Primary, secondary and tertiary

Question 2

What is the functional group for alcohols

Answer 2

OH

Question 3

Draw the structures for primary, secondary and tertiary alcohols

Answer 3

Check physical flashcards for answers

Question 4

How can alkenes be formed from alcohols?

Answer 4

By dehydrating alcohols

Question 5

Describe a dehydration reaction and give the formula

Answer 5

• Eliminating water from alcohols
• CnH2n+1OH -> CnH2n + H2O

Question 6

How are alkenes produced from renewable resources

Answer 6

• Plants contain glucose and the fermentation of glucose produces ethanol

Question 7

Give one industrial use for alkenes

Answer 7

Starting material for polymers

Question 8

What is the catalyst for the dehydration of alcohols

Answer 8

Concentrated sulfuric acid or phosphoric acid

Question 9

What is the product of the dehydration using catalysts

Answer 9

A mixture with water, acid and reactant so the alkene has to be separated out

Question 10

Draw the mechanism for the elimination of water from ethanol

Answer 10

Check physical flashcards for answers

Question 11

Describe the mechanism of the elimination of water from ethanol

Answer 11

• A lone pair of electron on oxygen bonds to an H+ from the acid. The alcohol is protonated giving the oxygen a positive charge

• The positively charge oxygen pulls electrons away from carbon. The H2O leaves, leaving an unstable carbocation intermediate

• The carbocation loses an H+ and an alkene is formed

Question 12

Why do more complicated alcohols form more than one product?

Answer 12

Because the double bond can form on either side of the carbon with the OH group attached

Question 13

What process is used to separate chemicals?

Answer 13

Distillation

Question 14

Why are organic compounds purified?

Answer 14

They contain impurities

Question 15

How is a pure alkene produced

Answer 15

By separating from other substances e.g products, reactant, acid and water

Question 16

Why does the distillation technique work?

Answer 16

Different chemicals have different boiling points to separate them

Question 17

Name the stages that are needed in producing cyclohexene from cyclohexanol

Answer 17

Distillation, Separation and purification

Question 18

Describe the distillation process

Answer 18

• Add H2SO4 and H3PO4 to a round bottom flask containing cyclohexanol. Swirl the flask and add 2-3 carborundum boiling chips

• Mixture should be gently heated to 83 degrees Celsius using a water bath or electric heater

• At this temperature the chemicals will evaporate. The warm gas will rise into the condenser with cold water running through the outside which turns it into a liquid

Question 19

Describe the separation stage

Answer 19

• Transfer the product to a separating funnel to dissolve water soluble impurities and create an aqueous solution

• Allow the mixture to settle into layers. Drain the aqueous lower layer, leaving the impure cyclohexane

Question 20

Describe the stage of purification

Answer 20

• Drain the cyclohexane into a round-bottomed flask

• Add anhydrous CaCl2 and stopper the flask. Let the mixture dry for at least 20minutes with occasional swirling.

• The cyclohexane will still have small amounts of impurities so distill the mixture one last time

Question 21

What is the reagent for the elimination of water from an alcohol and what is the condition?

Answer 21

• Concentrated H2SO4/ Phosphoric acid
• hot temperature

Question 22

Why cant tertiary alcohols be oxidized

Answer 22

They have no hydrogen on the central atom