Castor oil is a vegetable oil obtained by pressing the seeds of the castor oil plant (Ricinus communis). The common name “castor oil”, from which the plant gets its name, probably comes from its use as a replacement for castoreum, a perfume base made from the dried perineal glands of the beaver (castor in Latin).
Castor oil and its derivatives are used in the manufacturing of soaps, lubricants, hydraulic and brake fluids, paints, dyes, coatings, inks, cold resistant plastics, waxes and polishes, nylon, pharmaceuticals and perfumes.
What Are Castor Beans?
Castor beans are the seeds of the castor oil plant Ricinus communis. The plant is native to East Africa, although it can be found all around the Mediterranean region and Indian subcontinent. Many people in America even grow a castor bean plant in their garden to help keep pests away.
The castor oil plant is a member of the spurge family. The seeds from the castor oil plant are rich in oil, which comprises between 40% and 60% of the weight of the seeds. The oil, which is usually obtained by cold pressing the seeds, has many medicinal and industrial uses.
Many people associate castor beans with the poison ricin. While it is true that the seed case from the castor bean plant contains a small quantity of ricin, this toxin is not soluble in oil. When the seeds are pressed, the oil is free from any toxins and is therefore perfectly safe for medicinal use and beauty treatments.
The United States Food and Drug Administration (FDA) has categorized castor oil as “generally recognized as safe and effective” (GRASE) for over-the-counter use as a laxative with its major site of action the small intestine where it is digested into ricinoleic acid. Despite castor oil being widely used to induce labor in pregnant women, to date there is not enough research to show whether it is effective to ripen the cervix or induce labor. Therapeutically, modern drugs are rarely given in a pure chemical state, so most active ingredients are combined with excipients or additives. Castor oil, or a castor oil derivative such as Kolliphor EL (polyethoxylated castor oil, a nonionic surfactant), is added to many modern drugs, including:
- Miconazole, an antifungal agent
- Paclitaxel, a mitotic inhibitor used in cancer chemotherapy
- Sandimmune (cyclosporine injection, USP), an immunosuppressant drug widely used in connection with organ transplant to reduce the activity of the patient’s immune system
- Nelfinavir mesylate, an HIV protease inhibitor
- Tacrolimus, an immunosuppressive drug (contains HCO-60, polyoxyl 60 hydrogenated castor oil)
- Xenaderm ointment, a topical treatment for skin ulcers, is a combination of Balsam of Peru, castor oil, and trypsin
- Aci-Jel (composed of ricinoleic acid from castor oil, with acetic acid and oxyquinoline) is used to maintain the acidity of the vagina.
In naturopathy castor oil has been promoted as a treatment for a variety of human health conditions, including cysts. The claim has been made that applying it to the skin can help cure cancer. However, according to the American Cancer Society, “available scientific evidence does not support claims that castor oil on the skin cures cancer or any other disease.”
Castor oil is used as bio-based polyol in the polyurethane industry. The average functionality (number of hydroxyl groups per triglyceride molecule) of castor oil is 2.7, so it is widely used as rigid polyol and coating.
Castor oil is not a drying oil, meaning that it has a low reactivity toward air compared to other oils such as linseed oil and tung oil. Dehydration of castor oil gives linoleic acids, which does have drying properties.
Castor oil can be broken down into other chemical compounds that have numerous applications. Transesterification followed by steam cracking gives undecylenic acid, a precursor to specialized polymer nylon 11, and heptanal, a component in fragrances. Breakdown of castor oil in strong base gives 2-octanol, both a fragrance component and a specialized solvent, and the dicarboxylic acid sebacic acid. Hydrogenation of castor oil saturates the alkenes, giving a waxy lubricant.
The production of lithium grease consumes a significant amount of castor oil. Hydrogenation and saponification of castor oil yields 12-hydroxystearic acid which is then reacted with lithium hydroxide or lithium carbonate to give high performance lubricant grease.
Since it has a relatively high dielectric constant (4.7), highly refined and dried castor oil is sometimes used as a dielectric fluid within high performance high voltage capacitors.
Castor oil was the preferred lubricant for rotary engines, such as the Gnome engine after that engine’s widespread adoption for aviation in Europe in 1909. It was used almost universally in rotary engined Allied aircraft in World War I. Germany had to make do with inferior ersatz oil for its rotary engines, which resulted in poor reliability.
The methanol-fueled two-cycle glow plug engines used for aeromodelling, since their adoption by model airplane hobbyists in 1948, have used varying percentages of castor oil as a lubricant. It is highly resistant to degradation when the engine has its fuel-air mixture leaned for maximum engine speed. Gummy residues can still be a problem for aeromodelling powerplants lubricated with castor oil, however, usually requiring eventual replacement of ball bearings when the residue accumulates within the engine’s bearing races. One British manufacturer of sleeve valved four-cycle model engines has stated the “varnish” created by using castor oil in small percentages can improve the pneumatic seal of the sleeve valve, improving such an engine’s performance over time.
Turkey red oil, also called sulphonated (or sulfated) castor oil, is made by adding sulfuric acid to vegetable oils, most notably castor oil.[36] It was the first synthetic detergent after ordinary soap. It is used in formulating lubricants, softeners, and dyeing assistants.
Castor oil, like currently less expensive vegetable oils, can be used as feedstock in the production of biodiesel. The resulting fuel is superior for cold winters, because of its exceptionally low cloud and pour points.
Initiatives to grow more castor for energy production, in preference to other oil crops, are motivated by social considerations. Tropical subsistence farmers would gain a cash crop.
source: wikipedia.com