Wk 6: Functional groups 2

Question 1

Describe carboxylic acids

Answer 1

• Formula: RCOOH
• Functional group: Carboxyl (COOH)
• Short chain carboxylic acid form multiple H bonds
  
  • Very water soluble
• Naming: -oic acid

Question 2

Carboxylic acids in biomolecules

Answer 2

• Vinegar (ethanoic acid)
• Odour and flavours (cheese and fruit)
• Rancidity (butter/dairy)
• Ant venom (formic acid)
• Fruit acids (citrus)
• Essential metabolic intermediates (pyruvate)

Question 3

Describe Esters

Answer 3

• Formula: RCOOR’
• Functional group: modified carboxyl group (-COOR)
• Formed from esterification rxn (condensation)
  
  • Carboxylic acid + alcohol
• Naming:
  
  • 1st alcohol +2nd acid
  • Ethanol + propanoic acid = ethyl propanoate

Question 4

Biomolecule example of ester

Answer 4

• Triglycerides (glycerol + 3 fatty acids)
  
  • Fat
  • Hydrophobic tail negates hydrophilic polar head group reducing water solubility

Question 5

Which functional groups have nitrogen

Answer 5

Amines and amides

Question 6

General Features of amines

Answer 6

• Generic Formula: RNH2
• Carbon framework attached to amino group
• Naming: -amine or -ylamine

Question 7

Types of amines

Answer 7

• Primary: N bonded to 1 R/Ar group, rest is H
• Secondary: N bonded to 2 R/Ar groups, other is H
• Tertiary: N bonded to 3 R/Ar groups

Question 8

Trimethylaminuria

Answer 8

genetic disorder when body can’t metabolise certain N compounds like trimethylamine
- builds up and is released into secretions, giving fishy odour

Question 9

What are quaternary amines?

Answer 9

• N bonded to 4 groups
• Polyatomic cation
  
  • N carries + charge
• Example:
  
  • Acetylcholine: neurotransmitter in ANS and PNS
  • N + 3 methyl groups

Question 10

What are heterocyclic amines?

Answer 10

Cyclic compounds with 1+ N atoms in the ring (not attached)
E.g: purine and pyrimidine (DNA and RNA)

Question 11

What are physical properties of amines

Answer 11

• • 1, 2 and 3 amines form hydrogen bonds to different extents
    
    • 1>2>3
  • Water soluble
  • Amines function as bases
    
    • N has lone pair of electrons

Question 12

Important biomolecules that are amines

Answer 12

• Acetylcholine
• Adrenaline
• Dopamine
• Serotonin

Question 13

General Features of Amides

Answer 13

• Generic formula: RCONHR’
• Functional group: amide (carbonyl group attached directly to N atom)
• Naming: -amide

Question 14

Types of amides

Answer 14

• Based off of the amine group
  
  • Primary: N bonded to 2 H atoms
  • Secondary: N bonded to 1 H and 1 alkyl group
  • Tertiary: N bonded to 2 alkyl groups
  • Quaternary: polyatomic ion

Question 15

Physical properties of amides

Answer 15

• Highest MP and BP of all covalent organic compounds
• Slightly higher water solubility than carboxylic acids

Question 16

Biomolecule examples of amides

Answer 16

• Medications
• Proteins
  
  • 2 amino acids join in condensation reaction
  • Amino group of 1st A.A links to carboxyl group of second A.A

Question 17

General features of thiols

Answer 17

• Formula: RSH
• S has equivalent electronegativity to C
• Does not induce polarity or facilitate H bonding
• Naming: -thiol

Question 18

Physical properties of thiols

Answer 18

• Significant role in stabilising structure in biological macromolecules
• Neighbouring thiol groups form disulfide bonds
  
  • Important for protein folding (cysteine)