Key Principles

What are two effects of hydrogen bonding among alcohols?

1. Increases boiling point
2. Increases miscibility in water

What contributes to the acidity of alcohols?

• The hydroxyl groups of alcohols makes them protic solvents, i.e. solvents capable of donating a proton (hydrogen).
• The presence of stabilizing resonance structures, e.g. an aromatic ring with one hydroxyl group (aka phenols) makes aromatic alcohols more acidic than straight-chained alcohols.

What is the acidity of simple alcohols (e.g. CH$_{3}$OH) compared to water?

Quite similar: the $pK_{a}$ of H$_{2}$O is 15.74 while the $pK_{a}$ of methanol is 15.5:

$pK_{a} \ H_{2}O \sim pK_{a} \ CH_{3}OH$

What is the effect of hydrocarbon branching on the physical properties of alcohols?

Increasing hydrocarbon branching negates the effects of the hydoxyl group(s). Therefore, properties ascribed to hydrocarbons (non-polarity, hydrophobicity, miscibility in organic solvents) prevail and hydroxyl properties (polarity, hydrophilicity, hydrogen bonding) are less dominant.