4.2.1 Alcohols Flashcards Preview

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Flashcards in 4.2.1 Alcohols Deck (19)
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1

Functional Group of Alcohols

-OH (hydroxyl group)

2

Polarity of alcohols

O-H bond on alcohols is polar O is slightly negative while H is slightly positive

3

Why do alcohols have a high bp/mp than alkanes of a similar Mr?

Hydrogen bonding
OH group allows to form h-bonds with other alcohol molecules (strong IM forces)

4

Why do alcohols have a low volatility?

due to h-bonds, strong IM force so more energy needed to separate molecules

5

Solubility of Alcohols in water

are able to form h-bonds due to polarity in hydroxyl group so are soluble in water.

6

solubility of alcohols in water and chain length

the longer the chain, the less soluble in water as only O-H group forms hydrogen bonds, the rest of the chain prefer to form london forces. Sometimes chain length can interfere with h-bonds

7

Classification of Alcohols

Primary Alcohols -> carbon with hydroxyl group is directly bonded to 1 other Carbon

Secondary Alcohols -> carbon with hydroxyl group is directly bonded to 2 other Carbons

Tertiary Alcohols-> carbon with hydroxyl group is directly bonded to 3 other Carbons

8

Oxidation of alcohols experiment observations

Orange to Green when the alcohol is oxidised

9

Oxidation of alcohols conditions

ACIDIFIED potassium dichromate and heat and reflux/ continuous distillation

10

What happens when an organic substance is oxidised?

take away 2H
add O

11

Why is acidified potassium dichromate a good oxidising agent?

Chromium has a very high oxidation number

12

Oxidising Alcohols products

primary- aldehyde (distillation) - carboxylic acid (reflux)
secondary- ketone (refulx)
tertiary- No Reaction

13

First oxidation of primary and secondary alcohols (process)

remove 2Hs, one from OH group, the other from the carbon containing hydroxyl group

14

Why don't tertiary alcohols oxidise?

there is no H on the Carbon with the OH

15

Elimination of H2O process (Dehydration)

Take H off OH group and one from H next carbon next to hydroxyl group (can result in a mixture of products)

16

Dehydration conditions

Acid catalyst ( concentrated H3PO4/ H2SO4)
Heat
under Reflux

17

General dehydration equation

Alcohol -> alkene + H2O

18

Substitution with halide ion process

swap OH for halogen

19

Substitution with halide ion conditions

react alcohol with acid and halide ion (NaBr/H2SO4)