4.2.1 Alcohols Flashcards
Functional Group of Alcohols
-OH (hydroxyl group)
Polarity of alcohols
O-H bond on alcohols is polar O is slightly negative while H is slightly positive
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)
Why do alcohols have a low volatility?
due to h-bonds, strong IM force so more energy needed to separate molecules
Solubility of Alcohols in water
are able to form h-bonds due to polarity in hydroxyl group so are soluble in water.
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
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
Oxidation of alcohols experiment observations
Orange to Green when the alcohol is oxidised
Oxidation of alcohols conditions
ACIDIFIED potassium dichromate and heat and reflux/ continuous distillation
What happens when an organic substance is oxidised?
take away 2H
add O
Why is acidified potassium dichromate a good oxidising agent?
Chromium has a very high oxidation number
Oxidising Alcohols products
primary- aldehyde (distillation) - carboxylic acid (reflux)
secondary- ketone (refulx)
tertiary- No Reaction
First oxidation of primary and secondary alcohols (process)
remove 2Hs, one from OH group, the other from the carbon containing hydroxyl group
Why don’t tertiary alcohols oxidise?
there is no H on the Carbon with the OH
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)
