Amines, Amino Acids, Peptides, and Proteins

Amines, Amino Acids, Peptides, and Proteins

Amines:

• 4 amines are gases at room temperature: methylamine, dimethylamine, trimethylamine, ethylamine.

• As the molecular weight increases: the boiling point increases and the solubility in water decreases.

• Physical properties of aniline: liquid, easily oxidized, insoluble in water, sinks to the bottom of the test tube.

• Phenomenon of aniline left in the air: colorless turns black.

• Does aniline change the color of litmus paper? No.

• Evidence of the influence of the benzene ring on the -NH2 group: the basicity of aniline is very weak, it does not change the color of litmus paper.

• Evidence of the influence of the -NH2 group on the benzene ring: aniline reacts with Br2 solution to form a white precipitate.

• What is used to remove the fishy smell of fish? Vinegar.

Amino Acids:

• Molecular weight of Gly, Ala, Val, glutamic acid, lysine: 75, 89, 116, 147, 146.

• How many carbons are there in a glutamic acid molecule? 5.

• How many carbons are there in a lysine molecule? 6.

• Structural formula of Val: CH3-CH(CH3)-CH(NH2)-COOH.

• Physical properties of amino acids: crystalline solids, easily soluble in water, and have high melting points.

• Amino acids are compounds with the structure: zwitterions.

• Monosodium salt of glutamic acid is used to: make MSG, monosodium glutamate.

• Glutamic acid is used to: make nerve support drugs.

• Methionine is used to: make liver supplements.

Peptides:

• Peptide bond is a bond: -CO-NH-.

• How many ?-amino acid residues are there in a tripeptide molecule? 3.

• Is it true that all peptides give a biuret color reaction with Cu(OH)2? False, except for dipeptides.

Proteins:

• Egg white is: albumin.

• Physical properties of proteins: many proteins are soluble in water to form colloids and coagulate when heated.

• When does coagulation and precipitation of proteins occur? When heated or when acid, base, or certain salts are added to the protein solution.

Order of basicity of dimethylamine, methylamine, aniline, and ammonia in decreasing order:

Dimethylamine > Methylamine > Ammonia > Aniline.

When aniline reacts with HCl solution to form a product, then CO2 is passed through it, the product obtained is in the form of: emulsion.