Deck 2: Classification of alcohols

Question 1

How do you classify a primary alcohol?

Answer 1

The -OH groups is attached to a carbon atom with no alkyl groups or bonded to one alkyl group.

Question 2

Is methanol a primary alcohol?

Answer 2

Yes, because the -OH group is attached to a carbon atom with no alkyl groups.

Question 3

How do you classify a secondary alcohol?

Answer 3

The -OH group is attached to a carbon atom bonded to two alkyl groups.

Question 4

Classify propan-2-ol and explain why.

Answer 4

• Propan-2-ol is a secondary alcohol
• Propan-2-ol has an -OH group attached to a carbon with two CH3 - alkyl groups.

Question 5

How do you classify wether an alcohol is a tertiary alcohol?

Answer 5

• The -OH is attached to a carbon atom bonded to three alkyl groups.

Question 6

Name a suitable oxidising agent used to oxidise primary and secondary alcohols.

Answer 6

Acidified dichromate ions H+/Cr₂O₇²⁺

Question 7

How can acidified dichromate ions be made?

Answer 7

This oxidising mixture can be made from potassium dichromate, K₂Cr₂O_7,and sulfuric acid, H₂SO_4.

Question 8

On gentle heating with acidfified potassium dichromate, a primary alcohol will be oxidised to produce what?

Answer 8

An alcohol will be oxidised to produce an alcohol.

Question 9

What does the symbol [O] represent?

Answer 9

The symbol [O] is used to represent the oxidising agent.

Question 10

Write the reaction for Propan-1-ol reacting with acidified potassium dichromate.

Answer 10

-H₂O is also released.

Question 11

For propan-1-ol to be oxidised to form propanal, what must the reaction conditions be?

Answer 11

• Gentle heating
• Using a distillation fraction to prevent the alcohol from completely reacting to form a carboxylic acid.

Question 12

Write out the reaction for propan-1-ol reacting with acidified dichromate to form a carboxylic acid and give the reaction conditions.

Answer 12

Question 13

Define reflux

Answer 13

Reflux is the continual boiling and condensing of a reaction mixture to ensure that the reaction takes place without the contents of the flask boiling dry.

Question 14

what is wrong about placing the condenser of a reflux the wrong way round?

Answer 14

If you connect a condenser the wrong wat around, the water cannot fill the outer water jacket of the condenser and it will not cool vapour efficiently. Water always enters lower than it leaves.

Question 15

Draw a reflux

Answer 15

Question 16

Draw distillation apparatus

Answer 16

Question 17

Secondary alcohols are oxidised by acidified dichromate ions to produce what?

Answer 17

To produce ketones.

Question 18

Write the reaction of the oxidation of butan-2-ol with acidified dichromate.

Answer 18

CH₃CH(OH)CH₂CH₃+ [O] —–> CH₃COCH₂CH₃+ H₂O

• Oxidising agent is acidified dichromate
• Reaction mixture is heater
• Product called butanone

Question 19

What is a tertiary alcohol?

Answer 19

The -OH group is attached to a carbon atom bonded to three alkyl groups.