In the SI, the. angle of optical rotation is expressed in radians (rad). The optical rotation is measured on a layer of suitable thickness (optical path length. l. ) at the wavelength Î». and temperature T specified in the monograph. A typical optical path length is 100 mm, the most common. wavelength is 589 nm (Sodium D-Line), while the reference temperature is usually between 20-25 Â°C.
Cetearyl, Cetyl, Myristyl and Behenyl Alcohols are straight-chain alcohols. Isostearyl Alcohol is a branched chain alcohol. Cetearyl Alcohol is a mixture of mostly of Cetyl and Stearyl Alcohols, which are fatty alcohols that occur naturally in small quantities in plants and animals. Myristyl Alcohol is a 14 carbon chain. Cetyl Alcohol has 16 carbons, while Stearyl and Isostearyl Alcohols have 18 carbons.
In keeping with this Section, Cetyl Alcohol must contain not less than. 98% of total alcohols and not less than 94% of straight-chain alcohols; Myristyl. Alcohol must contain not less than 99% of total alcohols and not less than 96%. of straight chain alcohols. (25) Also, technical grade Cetearyl Alcohol, approxi-. mately 65% to 80% stearyl alcohol and 20% to 35% Cetyl Alcohol, is required.