Enol-Keto tautomerism
The tautomeric migration of a hydrogen atom from an adjacent carbon atom to a carbonyl group of a keto-compound to produce the end form of the compound, the reverse process of hydrogen atom migration also occurs.
Epoxy resins
Polyethers obtained by condensation of epichlorophydrin with polyols like bisphenol A, or by epoxidation of Diels-Alder adducts with peroxy compounds. These are used as adhesives protective coatings, etc.

Equivalent electrons
Electron in an atom which have the same principal and orbital quantum numbers, but not necessarily the same magnetic orbital and magnetic spin quantum numbers.

Essential amino acid
Refers to an amino acid that an organism is unable to synthesize in sufficient quantities. It must therefore be present in the diet. In man, the essential amino acids are arginine, Histidine, lysine, threonine, methionine, isoleucine, leucine, valine, phenylanine, and tryptophan.

Ethylene oxide
1, 2-epoxyethane, oxirane CH2. CH2O. Colourless gas with a sweet odour which is somewhat lachrymatory; b.p. 10.50C.

Emulsification
The process of dispersing one liquid in a second immiscible liquid; the largest group of emulsifying agents are soaps, detergents, and other compounds, whose basic structure is a paraffin chain terminating in a polar group.