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Classification of resins


Classification of Resins

✓ Depending upon the type of the constituents:  

Resins are of three types: 

1). Acid resins examples Colophony contains abietic acid, Copaiba (copaivic and oxycopaivic acid), Myrrh (Commiphoric acid) etc 

2). Ester resins examples Benzoin (Coniferyl benzoate), Storax (Cinnamyl cinnamate) etc. 

3). Resin alcohols examples Peru balsam (Peruresinotannol), Guaiacum resin (Guaic resinol).

✓ Depending upon combination with other Constituents:

1). Gum resin: Gum resins are in homogenous combination of gum and resin. These are always associated with small quantities of other substances like bitter principle, enzymes and volatile oils etc. It may consist of two or more glycosidal acids in various proportions and contains trace amount of nitrogen e.g. Myrrh. 

2). Oleo resin: When resins are in homogenous combination with volatile oils or oily liquids, are called oleo resin. They are secreted in schizogenous or schizolysigenous ducts. Ginger, Capsicum, Turpentine oil. 

3. Oleo gum resin: These resins are in homogenous combination with volatile oil and gum. e.g. Asafoetida. 

4. Balsam resin: Those oleo resins which contain aromatic acids like benzoic acid or Cinnamic acid are known as balsam resin e.g. Benzoin. 

5. Glycoresin: These are made up of resin along with sugars e.g. Jalap, Ipomoea. 

            Some resins are complex natural substances not having transpose any specific chemical property, chemically inert and do not get hydrolysed are known as resenes. Few examples are asafoetida, colophony etc. 

Properties of resins: 

1. These are amorphous and brittle in nature. 

2. They occur in translucent hard solid form. 

3. The resin softens and finally melted upon heating. 

4. They have specific gravity ranges from 0.9 to 1.25.

5. When burnt, they produce smoky flame. 

6. They are bad conductor of electricity. 

7. They are soluble in organic solvents like alcohol, ether and chloroform. 

8. They are insoluble in water. 

9. The resin film formed upon drying becomes hard and transparent which is unaffected by moisture and air. 

10. Majority of resins undergo slow atmospheric oxidation which darkens its colour and impaired solubility.