Lauryl Alcohol This alcohol, more technically known as n.dodecanol, is obtained from coconuts, where the interior triglyceryl laurate content is treated with NaOH to form sodium laurate, converted to the corresponding acid and reduced to the alcohol. Lauryl alcohol is sometimes separated from myristyl, stearyl and other “palm tree alcohols” by careful fractionation. Pure lauryl alcohol is a non-VOC, with a flash point of about 355°F (179.4°C). It has a very faint, pleasing odor. Lauryl alcohol is often included in aerosol foam products, such as shaving creams. For example, a dispersion of 5% Triethanolamine (TEA) Laurate in water, pressurized with 4% A46, was modified by the addition of 4% lauryl alcohol. The foam stability was 100 times better, the drainage was eight times slower, the foam stiffness was three times greater and the average initial bubble size was five times smaller. Myristyl alcohol gave the same or even better results. Attractive pearlescence (iridescence) effects have often resulted when these alcohols are used at certain levels. Cetyl Alcohol This C16 alcohol, also called n.Tetradecanol (but almost never Palmityl Alcohol), apparently takes its preferred name from its original source in Spermaceti (cetyl palmitate) from sperm whales. Like lauryl alcohol, it is now synthesized from glycerides produced in palm tree coconuts. The amount runs from about 25–50% of all the coconut alcohols, although usually less than lauryl alcohol. Today, the main source is animal lard. Its physical properties and uses are very similar to those of lauryl alcohol. Along with stearyl alcohol, it can be used in the formulation of anhydrous foam products based on either Polyethylene Glycol 400 or light mineral oil. Such compositions as 0.6% Chlorohexadene Gluconate, with 2% cetyl alcohol and 2% stearyl alcohol, plus other ingredients, can be used to control diaper rash and other dermal problems. However, its primary aerosol use is as a foam stabilizer and stiffening agent. Stearyl Alcohol More technically called n.Hexadecanol, C18-H38-OH, this white crystalline solid is synthesized from mixed triglycerides found in coconuts. It is usually about a 6–12% ingredient. It can be separated from the other coconut-based alcohols by distillation under about 15mm absolute pressure. Since coconuts carry the seeds of future palm trees, there are current concerns about over-harvesting them. In a few cases, governments have enacted protective regulations, but the increasing popularity of mild coconutbased detergents has led to poaching practices that may limit the availability of these important products in future years. A much more important source for stearyl alcohol is animal lard, which is rich in the triglycerides of palmitic and stearic acids. The acids are isolated by saponification with sodium hydroxide, NaOH, then converted to the ethyl esters, which are then reduced by hydrogen to the respective alcohols. The individual alcohols can then be separated by vacuum distillation. Stearyl alcohol is a non-VOC, with a flash point of 385°F (196.1°C). It has essentially no vapor pressure and is almost odorless (although some perfumers report a very slight bay odor). It is very slightly more irritating to sensitive skin than lauryl and myristyl alcohols. It is also slightly more effective as a foam stiffening agent than the other fatty alcohols. Other high-end alcohols These start with arachidyl alcohol, m.p. 32.8°C (91°F) (C20H41-OH) and behenyl alcohol, m.p. 34°C (93.2°F) (C22H45-OH), present in very small amounts in nature as their triglycerides. A major supplier offers behenyl alcohol as a superior foam stiffening and texturizing agent—more effective than stearyl alcohol. Compounds such as behenic acid, glyceryl tribehenate, behenamine oxide and behenic ethoxylates are also available. Still higher aliphatic alcohols are available from natural waxes. Lignoceryl alcohol, m.p. 34.4°C (93.9°F) (C24H49-OH) is obtained from Carnauba wax. The natural wax alcohols end at gossypyl alcohol, m.p. 79.7°C (175.4°F), (C34H69-OH) obtained from cotton. While still higher alcohols have been reported, they are chemical curiosities made by lengthening the “R” chain of simpler alcohols. Spray Threepiece 202 x 314 lined can. 42 Spray March 2017
Spray March 2017
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