CASTOR OIL DERIVATIVES PRODUCTS

Castor oil is extracted from castor seeds and is used either in its crude form or in the refined hydrogenated form. Generally, 65% of it is processed (about 28% is refined, 12% is hydrogenated, 20% is dehydrated and the balance 5% is processed to manufacture other derivatives). The major derivatives of castor oil used in the industry are hydrogenated castor oil (HCO), dehydrated castor oil (DCO) and Sebacic acid etc.

Castor oil is derived from the seeds of the plant Ricinus Communis, which occurs naturally in almost all tropical and near-tropical areas as a perennial. It is also widely found in temperate climates, but where frost occurs, the plant must be cultivated as an annual.

The seeds of the plant, commonly called castor beans, grow in clusters on spikes of the plant. The seed or bean itself is encased in a spiny outer shell, from which it may be separated by mechanically dehulling, or by sun-drying in the open until the casing splits. The bean itself consists approximately of 75% kernel and 25% husk. The oil content of the whole seed varies between 35-55%. A typical analysis will show: moisture – 5. 5%; oil -48.6%, protein – 17.9%; carbohydrate – 13.0%; fiber – 12.5%; and ash – 2.5%.

The oil is a rarity in nature, being almost a pure compound – about nine-tenths the glyceride of ricinoleic acid. The average fatty acid composition of castor oil is 86% ricinoleic, 8% oleic, 3%- linoleic. And 3% stearic and dihydroxystearic.

Although the mealy residue of bean following oil extraction is high in protein (about 35%) it is not suitable for use as a foodstuff due to the presence of the toxic albumin ricin. The ricin may be deactivated to some degree by steaming or heating. But since the bean also contains heat-stable allergenic materials, it is advisable not to use it as a feed ingredient.

Castor Oil Derivatives

For uses other than medicinal or lubrication, castor oil may be processed in several ways:

1) Sulfonation: Treatment of castor oil with concentrated sulfuric acid yields the sulfonated (actually sulfated) ester known as “Turkey-red” oil. This product is an anionic wetting agent widely used in textile drying and finishing.

2) Blown or Oxidized Castor Oils: Bringing castor oil into intimate contact with air or oxygen at elevated temperatures produces an oxidized or partially polymerized oil in a wide range of viscosities, color 3, and acid values. These oxidized oils are used as plasticizers or elasticizers in the manufacture of nitrocellulose films, artificial leathers and oilcloths.

3) Dehydration: The dehydration of castor oil can be controlled to yield two d1stinct types of material. One is the partially dehydrated oil which is soluble in mineral oil or glycols. Although this oil was once widely used as a lubricant it has been supplanted in recent years by specially “tailored” mineral lubricants. Its major present use is due to its low viscosity index — in shock absorber fluids and brake and hydraulic fluids.

Fully dehydrated castor oil is an excellent drying oil, the equivalent of good tung oil. This dehydrated 0il is the largest single present use of castor oil. The oil is dehydrated by heating to elevated temperatures, in vacua, in the presence of metallic salt catalysts.

4) Hydrogenation: The complete hydrogenation of castor oil yields essentially trihydroxystearin. m. p. 85-870C. a waxy fat. Partial hydrogenations will yield intermediate melting point fats. Hardened castor oils are utilized in the manufacture of certain waxes, ointments and cosmetics. Hydrogenation is accomplished under H2 pressure and moderately elevated temperatures in the presence of nickel catalyst.

5) Saponification: Saponified castor oil is used to a minor degree in the production of lathering soaps. More recently, it has been used in increasing amounts as a chemical intermediate and as a source of such dibasic organic acids as suberic, sebacic, and azelaic, used for manufacture of nylon-type polymers.