Hydroxyl Compounds

Question 1

Why do alcohols have higher boiling point than alkanes of comparable Mr?

Answer 1

Larger amount of energy is needed to overcome the stronger hydrogen bonds between the alcohol molecules than the weaker id-id interactions between the alkane molecules.

Question 2

Describe the solubility of alcohols in water.

Answer 2

Alcohols are relatively more soluble in water than slammed due to the presence of the -OH group which enables them to form hydrogen bonds with water molecules. Solubility decreases as the number of carbon atoms increases as the bulky non polar aryl/alkyl groups in the higher alcohols hinder the formation of effective hydrogen bonds between alcohol and water molecules.

Question 3

State the reagents and conditions to prepare alcohols from alkenes.

Answer 3

(Laboratory method)
1. concentrated H2SO4, cold
2. H2O, heat

(Industrial method)
steam, conc H3PO4 catalyst and heat

Question 4

State the reagents and conditions to prepare alcohols from halogenoalkanes.

Answer 4

Reagent and conditions: aqueous NaOH/KOH, heat

Question 5

State the reagents and conditions to prepare alcohols from aldehydes and ketones.

Answer 5

Reagents and conditions: LiAlH4 om dry ether, r.t OR NaBH4 in ethanol, r.t OR H2, Ni/Pt/Pd catalyst, r.t

Question 6

State the reagents and conditions to prepare alcohols from carboxlic acids.

Answer 6

Reagent and Conditions: LiAlH4 in dry ether, r.t