4.2.1: Alcohols Flashcards
Alcohol function group
R-OH
Primary alcohol
The carbon to which the OH group is attached has at least 2 hydrogens.
Secondary alcohol
The carbon to which the OH group is attached has 1 hydrogen.
Tertiary alcohol
The carbon to which the OH group is attached has 0 hydrogens.
Reasons for alcohol polarity (and ability to bond with water)
- OH bond is polar
* Lone pair of e- on oxygen atom can form hydrogen bonds (hydrophilic compared to hydrophobic rest of molecule)
Trend in alcohol solubility
• Solubility decreases with increasing length of chain
∵ More London forces so chains more strongly attract to each other than water
• Long wiggly chain gets in the way
• Higher proportion of the chain is hydrophobic
Volatility
The ease with which liquid turns to vapour
Boiling point of alcohol compared to alkane
• Boiling point of alcohol much higher than alkanes
∵ Both London forces and hydrogen bonds (that the alcohol formed to itself) must be broken)
Partial oxidation of a primary alcohol
Aldehyde + H₂O
Full oxidation of a primary alcohol
Carboxylic acid
Oxidation of a secondary alcohol
Ketone
Oxidation of a tertiary alcohol
Impossible
Oxidising agent (alcohol)
Acidified Potassium Dichromate
Cr₂O₇²⁻/H⁺
Heat under reflux to get
- Carboxylic acid from 1⁰ alcohol
* Ketone from 2⁰ alcohol
To get aldehyde from 1⁰ alcohol
Simple distillation
