Castor oil

Castor beans.
Castor oil in the light keeper's house at Split Rock Lighthouse in Minnesota.

Castor oil is a vegetable oil obtained by pressing the seeds of the castor oil plant (Ricinus communis).[1] 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).[2]

Castor oil is a colorless to very pale yellow liquid with a distinct taste and odor once first ingested. Its boiling point is 313 °C (595 °F) and its density is 961 kg/m3.[3] It is a triglyceride in which approximately 90 percent of fatty acid chains are ricinoleate. Oleate and linoleates are the other significant components.

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.[4]

Composition

Structure of the major component of castor oil.

Castor oil is well known as a source of ricinoleic acid, a monounsaturated, 18-carbon fatty acid. Among fatty acids, ricinoleic acid is unusual in that it has a hydroxyl functional group on the 12th carbon. This functional group causes ricinoleic acid (and castor oil) to be more polar than most fats. The chemical reactivity of the alcohol group also allows chemical derivatization that is not possible with most other seed oils. Because of its ricinoleic acid content, castor oil is a valuable chemical in feedstocks, commanding a higher price than other seed oils. As an example, in July 2007, Indian castor oil sold for about US$0.90 per kilogram (US$0.41 per pound)[5] whereas U.S. soybean, sunflower and canola oilseeds sold for about US$0.30 per kilogram (US$0.14 per pound).[6]

Average composition of castor seed oil / fatty acid chains
Acid name Average Percentage Range
Ricinoleic acid 85 – 95%
Oleic acid 2 – 6%
Linoleic acid 1 – 5%
α-Linolenic acid 0.5 – 1%  
Stearic acid 0.5 – 1%  
Palmitic acid 0.5 – 1%  
Dihydroxystearic acid 0.3 – 0.5%
Others 0.2 – 0.5%

Uses

Annually 270,000–360,000 tonnes (600–800 million pounds) of castor oil are produced for a variety of uses.[4]

Food and preservative

In the food industry, castor oil (food grade) is used in food additives, flavorings, candy (e.g., polyglycerol polyricinoleate or PGPR in chocolate),[7] as a mold inhibitor, and in packaging. Polyoxyethylated castor oil (e.g., Kolliphor EL)[8] is also used in the food industries.[9]

In India, Pakistan, Nepal and Bangladesh, food grains are preserved by applying castor oil. It stops rice, wheat, and pulses from rotting. For example, the legume pigeon pea is commonly available coated in oil for extended storage.

Medicine

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.[10] 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.[11] 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:

Alternative medicinal use

Advertisement of Castor oil as a medicine by Scott & Bowne company, 19th century

In naturopathy castor oil has been promoted as a treatment for a variety of human health conditions,[20] including cysts.[21] 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."[22]

Coatings

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.[1]

Castor oil is not a drying oil, meaning that it has a low reactivity toward air compared to say linseed oil and tung oil. Dehydration of castor oil gives linoleic acids, which does have drying properties.[1]

Precursor to industrial chemicals

Castor oil can be broken down into other chemical compounds that have numerous applications.[23][24][25] Transesterification followed by steam cracking gives undecylenic acid, a precursor to specialized polymer nylon 11, and heptanal, a component in fragrances.[26] Break down 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.[1]

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.[27]

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.

Lubrication

Vegetable oils like castor oil are typically unattractive alternatives to petroleum-derived lubricants because of their poor oxidative stability.[28][29] Castor oil has better low temperature viscosity properties and high temperature lubrication than most vegetable oils, making it useful as a lubricant in jet, diesel, and racing engines.[30] The viscosity of castor oil at 10 °C is 2,420 centipoise.[31] However, castor oil tends to form gums in a short time, and therefore its usefulness is limited to engines that are regularly rebuilt, such as racing engines. The lubricants company Castrol took its name from castor oil.

Castor oil has been suggested as a lubricant for bicycle pumps because it does not degrade natural rubber seals.[32]

Early aviation and aeromodelling

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.[33][34][35]

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

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.[37]

Biodiesel

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, due to its exceptionally low cloud and pour points.[38]

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.[39]

Punishment

Parents often punished children with a dose of castor oil.[40][41] Physicians recommended against the practice because they did not want medicines associated with punishment.[42]

A heavy dose of castor oil could be used as a humiliating punishment for adults, especially political dissenters. Colonial officials used it in the British Raj (India) to deal with recalcitrant servants.[43]

The most famous use as punishment came in Fascist Italy under Benito Mussolini. It was a favorite tool used by the Blackshirts to humiliate their opponents.[44][45][46] Political dissidents were force-fed large quantities of castor oil by Fascist squads. This technique was said to have been originated by Gabriele D'Annunzio. Victims of this treatment did sometimes die, as the dehydrating effects of the oil-induced diarrhea often complicated the recovery from the nightstick beating they also received along with the castor oil; however, even those victims who survived had to bear the humiliation of the laxative effects resulting from excessive consumption of the oil.[47]

It is said that Mussolini's power was backed by "the bludgeon and castor oil". In lesser quantities, castor oil was also used as an instrument of intimidation, for example, to discourage civilians or soldiers who would call in sick either in the factory or in the military. It took decades after Mussolini's death before the myth of castor oil as a panacea for a wide range of diseases and medical conditions was totally demystified, as it was also widely administered to pregnant women, elderly or mentally-ill patients in hospitals in the false belief it had no negative side effects.

Today, the Italian terms manganello and olio di ricino, even used separately, still carry strong political connotations (especially the latter). These words are still used to satirize patronizing politicians, or the authors of disliked legislation. They should be used with caution in common conversation. The terms Usare l'olio di ricino, ("to use castor oil") and usare il manganello ("to use the bludgeon") mean "to coerce or abuse", and can be misunderstood in the absence of proper context.

As a means of punishment or torture, force-feeding castor oil still lives on in animated cartoons such as Tom and Jerry.

Safety

The castor seed contains ricin, a toxic protein. Heating during the oil extraction process denatures and deactivates the protein. However, harvesting castor beans may not be without risk.[48] Allergenic compounds found on the plant surface can cause permanent nerve damage, making the harvest of castor beans a human health risk. India, Brazil, and China are the major crop producers, and the workers suffer harmful side effects from working with these plants.[49] These health issues, in addition to concerns about the toxic byproduct (ricin) from castor oil production, have encouraged the quest for alternative sources for hydroxy fatty acids.[50][51] Alternatively, some researchers are trying to genetically modify the castor plant to prevent the synthesis of ricin.[52]

While castor oil is sometimes used to induce full-term pregnancies (scientific evidence of its effectiveness is lacking),[53] consuming castor oil to treat constipation is not considered safe in pregnancies that are not at full term yet, since it may cause contractions of the womb.[54]

See also

References

  1. 1 2 3 4 Thomas, Alfred (2005). "Fats and Fatty Oils". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a10_173.
  2. ↑ Casselman, William Gordon. "Castor". Bill Casselman's Canadian Word of the Day. Retrieved 2014-08-09.
  3. ↑ Aldrich Handbook of Fine Chemicals and Laboratory Equipment. Sigma-Aldrich. 2003.
  4. 1 2 Mutlu, H; Meier, MAR (January 2010). "Castor oil as a renewable resource for the chemical industry". European Journal of Lipid Science and Technology 112 (1): 10–30. doi:10.1002/ejlt.200900138.
  5. ↑ "July 2007 commodity price for Indian castor oil". Archived from the original on September 27, 2007. Retrieved 2008-08-10.
  6. ↑ "Seed oil prices" (PDF). United States Department of Agriculture. July 2007. p. 31. Archived from the original (PDF) on April 6, 2008. Retrieved 2008-08-10.
  7. ↑ Wilson, R; Van Schie, BJ; Howes, D (1998). "Overview of the preparation, use and biological studies on polyglycerol polyricinoleate (PGPR)". Food and Chemical Toxicology 36 (9–10): 711–8. doi:10.1016/S0278-6915(98)00057-X. PMID 9737417.
  8. ↑ "BASF Technical data sheet on Cremophor EL" (PDF). Retrieved 2007-08-01.
  9. ↑ Busso, C; Castro-Prado, MA (March 2004). "Cremophor EL stimulates mitotic recombination in uvsH//uvsH diploid strain of Aspergillus nidulans". Anais da Academia Brasileira de Ciências 76 (1): 49–55. doi:10.1590/S0001-37652004000100005. PMID 15048194.
  10. ↑ "Ingredient List A-C" (PDF). FDA (see page 52 of this link). Archived from the original (PDF) on 2006-12-17. Retrieved 2006-12-28.
  11. ↑ Kelly, AJ; Kavanagh, J; Thomas, J (2013). "Castor oil, bath and/or enema for cervical priming and induction of labour". Cochrane Database of Systematic Reviews (7): CD003099. doi:10.1002/14651858.CD003099.pub2.
  12. ↑ Marmion, LC; Desser, KB; Lilly, RB; Stevens, DA (September 1976). "Reversible thrombocytosis and anemia due to miconazole therapy". Antimicrobial Agents and Chemotherapy 10 (3): 447–9. doi:10.1128/aac.10.3.447. PMC 429768. PMID 984785. See page 1, Methods and Materials.
  13. ↑ Fromtling, RA (1 April 1988). "Overview of medically important antifungal azole derivatives". Clinical Microbiology Reviews 1 (2): 187–217. PMC 358042. PMID 3069196. See page 6, /192, Clinical studies
  14. ↑ Micha, JP; Goldstein, BH; Birk, CL; Rettenmaier, MA; et al. (February 2006). "Abraxane in the treatment of ovarian cancer: the absence of hypersensitivity reactions". Gynecologic Oncology 100 (2): 437–8. doi:10.1016/j.ygyno.2005.09.012. PMID 16226797.
  15. ↑ "Sandimmune ingredients". DailyMed. Retrieved 2007-01-06.
  16. ↑ Zhang, KE; Wu, E; et al. (April 2001). "Circulating metabolites of the human immunodeficiency virus protease inhibitor nelfinavir in humans: Structural identification, levels in plasma, and antiviral activities". Antimicrobial Agents and Chemotherapy 45 (4): 1086–93. doi:10.1128/AAC.45.4.1086-1093.2001. PMC 90428. PMID 11257019.
  17. ↑ "Product Information: Xendaderm topical ointment, balsam Peru, castor oil and trypsin topical ointment". San Antonio, TX: Healthpoint, Ltd. 2002. Archived from the original on 2007-08-31. Retrieved 2007-10-11.
  18. ↑ Beitz, JM (June 2005). "Heparin-induced thrombocytopenia syndrome bullous lesions treated with trypsin-balsam of peru-castor oil ointment: A case study". Ostomy Wound Manage 51 (6): 52–4, 56–8. PMID 16014993.
  19. ↑ "Aci-Jel (Vaginal Jelly) drug description". RxList. Retrieved 2007-10-26.
  20. ↑ "Castor Oil Health Benefits". homeremediesweb.com. Retrieved 2015-10-02.
  21. ↑ "Cyst Treatment". earthclinic.com. 10 April 2015. Archived from the original on 13 April 2015.
  22. ↑ "Castor Oil". American Cancer Society. March 2011. Archived from the original on 2013-02-09. Retrieved 2013-09-22.
  23. ↑ "Multiple uses of castor oil". Retrieved 2007-08-02.
  24. ↑ "Castor oil as a renewable resource for the chemical industry". Onlinelibrary.wiley.com. 2010-01-25. Retrieved 2014-08-09.
  25. ↑ Ogunniyi, D.S. (June 2006). "Castor oil: A vital industrial raw material". Bioresource Technology 97 (9): 1086–91. doi:10.1016/j.biortech.2005.03.028. PMID 15919203. Archived from the original on May 6, 2009.
  26. ↑ Ashford's Dictionary of Industrial Chemicals, Third edition, 2011, page 6162
  27. ↑ Kirk-Othmer Encyclopedia of Chemical Technology. Archived from the original on July 14, 2011. Retrieved 2010-07-12.
  28. ↑ "Chemical modification to improve vegetable oil lubricants". Retrieved 2007-08-02.
  29. ↑ "Petroleum Oil and the Environment". DOE. Retrieved 2006-12-28.
  30. ↑ McGuire, Nancy (2004). "Taming the Bean". The American Chemical Society. Archived from the original on September 27, 2006. Retrieved 2007-08-02.
  31. ↑ Brady, George S.; Clauser, Henry R.; Vaccari, John (1997). Materials Handbook (14th ed.). New York: McGraw-Hill. ISBN 0070070849.
  32. ↑ Older, Jules (2000). Backroad and Offroad Biking. Mechanicsburg, PA: Stackpole Books. p. 37. ISBN 0811731502.
  33. ↑ Guilmartin, John F., Jr. (1994). "Technology and Strategy: What Are the Limits?". Two Historians in Technology and War. United States Army War College, Strategic Studies Institute. p. 10. ISBN 1428915222.
  34. ↑ Fisher, Suzanne Hayes (1999). "Aircraft, production during the war". In Tucker, Spencer C.; Wood, Laura Matysek; Murphy, Justin D. The European Powers in the First World War: An Encyclopedia. Taylor & Francis. p. 10. ISBN 081533351X.
  35. ↑ US Tariff Commission (1921). Tariff Information Surveys on the Articles in Paragraphs 44 and 45 of the Tariff Act of 1913. Washington, DC: Government Printing Office. p. 40.
  36. ↑ "Turkey Red Oil – A defoaming & wetting agent". Porwal.net. Retrieved 2014-08-09.
  37. ↑ "– Home of Castor Oil Online". Castoroil.in. Retrieved 2014-08-09.
  38. ↑ Biodiesel from Castor Oil: A Promising Fuel for Cold Weather (PDF) by Carmen Leonor Barajas Forero, 2004-10-12. Retrieved 2012-01-24.
  39. ↑ The Promise of the Castor Bean by Elizabeth Johnson, Biodiesel Magazine, 2004-12-01. Retrieved 2012-01-24.
  40. ↑ For an American example see David J. Rothman (1980). Conscience and Convenience: The Asylum and Its Alternatives in Progressive America. Transaction Publishers. p. 279. Retrieved 2015-10-29.
  41. ↑ For a Canadian examples see Neil Sutherland (1997). Growing Up: Childhood in English Canada from the Great War to the Age of Television. University of Toronto Press. p. 87. Retrieved 2015-10-29.
  42. ↑ Journal of the American Medical Association. American Medical Association. 1919. p. 1699. Retrieved 2015-10-29.
  43. ↑ Cecilia Leong-Salobir (2011). Food Culture in Colonial Asia: A Taste of Empire. Taylor & Francis. p. 66.
  44. ↑ "Italy The rise of Mussolini". Encyclopædia Britannica Online. Encyclopædia Britannica. 2007. Retrieved 2007-08-03.
  45. ↑ "Benito's Birthday". Time, in partnership with CNN. August 6, 1923. Retrieved 2007-08-03.
  46. ↑ Bosworth, R. J. B. (2002). Mussolini. New York: Arnold/Oxford Univ. Press. ISBN 0-340-73144-3.
  47. ↑ Cecil Adams (1994-04-22). "Did Mussolini use castor oil as an instrument of torture?". The Straight Dope. Retrieved 2014-08-09.
  48. ↑ Auld, DL; Pinkerton, SD; Rolfe, R; Ghetie, V; et al. (March–April 1999). "Selection of castor for divergent concentrations of ricin and ricinus communis agglutinin". Crop Science 39 (2): 353–7. Archived from the original on 2008-10-12. Retrieved 2007-07-31.
  49. ↑ "Hazards of harvesting castor plants". Retrieved 2007-07-31.
  50. ↑ Dierig, David A. (1995). "Lesquerella". New Crop FactSHEET. Center for New Crops & Plant Products, at Purdue University. Retrieved 2007-08-01.
  51. ↑ Dierig, David A. (2002). "Lesquerella" (PDF). The National Non-Food Crops Centre. Retrieved 2007-08-01.
  52. ↑ Wood, M (2001). "High-tech castor plants may open door to domestic production". Agricultural Research Magazine 49 (1). Retrieved 2007-08-02.
  53. ↑ Boel, ME; Lee, SJ; Rijken, MJ; Paw, MK; Pimanpanarak, M; Tan, SO; Singhasivanon, P; Nosten, F; McGready, R (October 2009). "Castor oil for induction of labour: not harmful, not helpful". Australian and New Zealand Journal of Obstetrics and Gynaecology 49 (5): 499–503. Retrieved 15 May 2015.
  54. ↑ "Drugs and Supplements: Laxative (Oral Route)". Mayo Clinic. Retrieved 15 May 2015.

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