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Chapter 22: Amines



Summary | Amines | Preparation of Amines | Reactions of Amines | Spectroscopic Analysis | Self Assessment | Quiz |


Summary

Chapter 22: Amines

Amines (e.g. RNH2) are organic derivatives of ammonia, NH3 (replace the N-H with N-C bonds) and have certain similarities with ammonia (e.g. basicity, nucleophilicity).

Nitrogen containing compounds are biologically very important amines, amino acids, amides, proteins, vitamins etc.

When looking at the Chime images, try to identify the N functional groups that are present.
 

COCAINE : C17H21NO4,  mol. wt. = 303.36 g/mol 
Cocaine is a central nervous stimulant found in the leaves of the coca plant.
 
 
 
 
 

N functional group ? tertiary amine
 

RANITIDINE : C13H22N4O3S,  mol. wt. = 314.41 g/mol 
Physical properties: Solid, mp = 69-70oC. US patent is held by Allen and Hanburys. 
The hydrochloride of Ranitidine is called Zantac, one of the most prescribed drugs in the western world as an  antiulcerative. Off white solid, mp = 133-134 oC. It is soluble in acetic acid, water and methanol, sparingly soluble in ethanol, insoluble in chloroform. 
Ranitidine is a histamine H2-receptor antagonist which inhibits gastric acid secretion.

N functional groups ? tertiary amine and nitro

PRONTOSIL : C12H13N5O2S,  mol. wt. = 291.33 g/mol 
The hydrochloride salt is an orange-red crystaline material, mp : 248-250 oC, solubility: 1g in 400 ml water, much more soluble in hot water, soluble in alcohol, acetone, fats and oils. 

Prontosil was original prepared as an "azo-dye" for wool fibers. However, in an in vivo study it was found to be active against Gram-positive infections and became a prototype compound that led to the development of the important sulphonamide antibacterials. Prontosil was first drug introduced to treat bacterial infections. 

N functional group ? tertiary amine

PROMAZINE : C17H20N2S, mol. wt. = 284.43 g/mol 
Physical properties: an oily liquid, having an "amine" odor. bp(0.3) : 203-210 oC. 
US patent for Promazine is held by Rhone-Poulenc. 
The hydrochloride salt, Prazine (also known as Talofen or Sparine) is a white/yellow crystalline material that oxidizes in air. One gram is soluble in 3 ml of water. it is also soluble in alcohols and chloroform, insoluble in diethyl ether and benzene. Aqueous solutions are slightly acidic to litmus. 
Used as an antipsychotic and an antihistamine in man and as a tranquilizer for animals. 

N functional group ? tertiary amines

NOVOCAIN : C13H20N2O2.HCl,  mol.  wt. = 273.07 g/mol 
Novocain,a crystaline material : mp = 153-156 oC, is the hydrochloride salt of Procaine. Numbing taste. Air stable. Solubility: 1g dissolves in 1ml water and 30ml of alcohol, slightly soluble in chloroform, virtually insoluble in diethyl ether. pH of 0.1M solution is 6.0. Aqueous solutions can be sterilised by boiling. LD50 (mice mg/kg) = 660.  Novocain was synthesised to replace cocaine due to the abuse of cocaine.  Designed to have the same pain-killing properties but without the psychological side effects. 
Used as a local anesthetic for humans and animals.
N functional group ? primary and tertiary amines
LIDOCAINE : C14H22N2O, mol. wt. = 234.34 g/mol 
Physical properties: crystaline needles (from benzene or alcohol) mp = 68-69oC, bpt (4mm) = 180-182oC. 
Soluble in chloroform, benzene, ether and alcohol. Insoluble in water. Developed from Procaine , which due to the presence of a labile ester bond, has only a short lifetime/duration of action. Changing this to a more stable amide linkage as in Lidocaine provides a material with a longer lifetime and therefore duration. The US patent is held by Astra. 
Used as a local anesthetic and a class IB antiarrhythmic.

N functional group ? amide and tertiary amine

DIAZEPAM : C16H13ClN2O, mol. wt. = 284.74 g/mol 
Physical properties: crystaline plates (from acetone and petroleum ether) mp = 125-126oC. pKa = 3.4. Soluble in chloroform, dimethyl formamide, benzene, acetone and alcohol. Slightly soluble in water. LD50 (orally for rats) = 710mg/kg 
This is a controlled substance in US code of Federal Regulations. US patent is held by Hoffmann-La Roche. 
Also known as Valium, Novazam amongst many other names. 
Therapeutically it is a anxiolytic, a skeletal muscle relaxant.
N functional group ? imine and tertiary amine
MIFEPRISTONE : C29H35NO2, mol. wt. = 429.60 g/mol 
Physical properties: mp = 150oC. Specific rotation = +138.5o (c = 0.5 in chloroform). Mifepristone is a progesterone receptor antagonist with partial agonist activity. When used with prostaglandins, Mifepristone terminates pregnancy within the first 9 weeks of gestation. Structurally it is very similar to Norethindrone. The US patent is held by Rousell-UCLAF. Also known as RU-486 and Mifegyne. 
Therapeutically it is used as an abortifacient.

N functional group ? primary amine

Information source: The Merck Index. 12th edition

The important organic reactions of amines (nucleophiles) are with the common electrophiles :

Amines Preparation of Amines Reactions of Amines Spectroscopic Analysis Problems

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