CD 1 - Bonding and Structure

Question 1

How do dyes attach themselves to fibres?

Answer 1

• Hydrogen bonding (and other intermolecular forces)
• Covalent bonds
• Ionic bonds

Question 2

What is the chromophore?

Answer 2

An atom or group responsible for the colour of a compound

Question 3

What functional groups modify the chromophore?

Answer 3

• Functional groups such as -OH, -NH2 or -NR2 are often added/attached to chromophores to alter the colour of the compound
• The groups added have lone electron pairs which join the system of delocalisation

Question 4

What functional groups allow the dye to bond to fibres?

Answer 4

• In polymers such as nylon, wool and silk, -COOH and -SO3H groups are attracted to the slightly basic -NH groups of the amide links
• OH groups allow hydrogen bonding to occur between the dye and fibre

Question 5

What functional groups affect the solubility of the dye?

Answer 5

• Auxochromes e.g. Carboxylic acid, sulfonic acid, amino and hydroxyl groups
• They are most commonly used to alter dye solubility