2.7.4 Chemical Properties of Resins
The various chemical properties of resins may be summarized as stated below:
1. Resins, in general, are enriched with carbon, deprived of nitrogen and contain a few oxygen in their respective molecules.
2. Majority of them undergo slow atmospheric oxidation whereby their colour get darkened with impaired solubility.
3. Resins are found to be a mixture of numerous compounds rather than a single pure chemical entity.
4. Their chemical properties are exclusively based upon the functional groups present in these substances.
5. Consequently, the resins are broadly divided into resin alcohols, resin acids, resin esters, glycosidal resins and resenes (i.e., inert neutral compounds).
6. Resins are regarded as complex mixtures of a variety of substances, such as: resinotannols, resin acids, resin esters, resin alcohols and resenes.
7. One school of thought believes that resins are nothing but oxidative products of terpenes.
8. They may also be regarded as the end-products of destructive metabolism.
9. The acidic resins when treated with alkaline solutions they yield soaps (or resin-soaps).
Note The solutions of resins in alkalies distinctly differ from ordinary soap solutions by virtue of the fact that the former cannot be easily ‘salted-out’ by the addition of NaCl, unless it is used in large excess quantity.
