CD (from PMT Notes)
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What are dyes?
Coloured compounds that chemically bond to a substrate and absorb light in the visible spectrum.
What is a chromophore?
An atom or chemical group responsible for the colour of a compound.
Which functional groups can modify a chromophore?
• -OH • -NH2 • -NR2
How do dyes bond to fibers?
By intermolecular forces, covalent bonds, and ionic bonds.
What groups in fibers attract dyes?
• -COOH • -SO3H • -NH groups
What are auxochromes?
Functional groups that alter the solubility of a dye, such as carboxylic acid, sulfonic acid, amino, and hydroxyl groups.
What are triglyceride esters?
Esters formed from glycerol and carboxylic acids through esterification.
How does the chain length of carboxylic acids in triglycerides vary?
Ranges from C4 to C22.
Why do oils have a lower melting point than fats?
Oils are more unsaturated, containing more carbon-carbon double bonds.
What is the effect of carbon-carbon double bonds on oil molecules?
They alter the shape, preventing close packing and reducing melting point.
What are the main types of reactions?
• Addition • Substitution • Oxidation • Reduction • Hydrolysis • Condensation • Elimination
What defines an aromatic compound?
Compounds that contain a benzene ring.
What is the molecular formula of benzene?
C6H6.
What stabilizes benzene compared to other molecules?
The delocalised electron ring structure.
What is the enthalpy change of hydrogenation for benzene?
-208 kJ mol-1.
What does the bond length evidence from X-ray diffraction show about benzene?
All bond lengths between carbon atoms are the same.
Why does benzene not undergo electrophilic addition reactions?
It would break the stable delocalised ring of electrons.
What type of reaction does benzene undergo instead of electrophilic addition?
Electrophilic substitution reactions.
What is halogenation in relation to benzene?
A type of electrophilic substitution where benzene reacts with halogens in the presence of a catalyst.
What is nitration in the context of benzene?
An electrophilic substitution where NO2+ is the electrophile.
What is produced during the nitration of benzene?
Nitrobenzene
What does Friedel-Crafts acylation involve?
The nucleophilic attack of the benzene ring on acyl chlorides.
What are diazonium salts?
Salts containing the diazonium ion, R-N2+.
What happens when diazonium salts react with phenol?
They form azo compounds.