Chemistry
Saponification
Saponification is a chemical reaction in which a fat or oil is hydrolyzed to produce glycerol and soap. It is typically carried out by treating the fat with a strong base, such as sodium hydroxide or potassium hydroxide. The process is commonly used in the production of soap and is an important reaction in organic chemistry.
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3 Key excerpts on "Saponification"
- Donald Pavia, George Kriz, Gary Lampman, Randall Engel(Authors)
- 2017(Publication Date)
- Cengage Learning EMEA(Publisher)
Those who could afford perfumes used them to hide their body odor. Perfumes, like fancy clothes, were status symbols for the rich. An inter -est in cleanliness again emerged during the eighteenth century, when disease-causing microorganisms were discovered. The process of making soap has remained practically unchanged for 2000 years. The procedure involves the basic hydrolysis or Saponification of an animal fat or a vegetable oil. Chemically, fats and oils are referred to as trigylcerides or triacylglycerols . They contain ester functional groups. Saponification involves heating a fat or oil with an alkaline solution. This alkaline solution was originally obtained by the leaching of wood ashes or from the evaporation of natural alkaline waters. Today, lye (sodium hydroxide) is used as the source of the alkali. The alka -line solution hydrolyzes the fat or oil into its component parts, the sodium salt of a long-chain carboxylic acid (soap) and an alcohol (glycerol). The following equation shows how soap is produced from a fat or oil. Soap Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300 224 A Microscale Approach to Organic Laboratory Techniques 6/e uni25A0 Pavia, Lampman, Kriz, Engel © 2018 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. T riglycerides T T (fat or oil) Carboxylic acid salts (soap) Glycer ol R 1 COO – Na + Saponification or hydrolysis NaOH R 2 COO – Na + R 3 COO – Na + A A B O R 1 C O O O CH 2 B O R 2 C O O O CH A A B O R 3 C O O O CH 2 A A HO HO HO O CH 2 O CH A A O CH 2 + The fatty acids are rarely of a single type in any given fat or oil. In fact, a single triglyceride molecule in a fat may contain three different acid residues (R 1 COOH, R 2 COOH, R 3 COOH), and not every triglyceride in the substance will be identical.
eBook - PDF- H. E. Garrett(Author)
- 2013(Publication Date)
- Pergamon(Publisher)
The lower quality fats used for soap-making have often undergone some enzymic degradation leading to the pres-ence of free fatty acids, diglycerides, and monoglycerides. These components are not entirely disadvantageous as the monoglycerides and the soap, formed initially by reaction of the free fatty acids with the first amounts of caustic alkali used, materially assist in the emulsifica- TABLE 2.1. TYPICAL FATTY ACID COMPOSITIONS OF SOME COMMON FATS Source of fat _^ j Coco-; Palm Palm 0 H v e jGroundjCottonj S u n component ~* nut ! kernel | fruit | j nut i seed j flower i i 1 ! ! seed Fatty Acid: Saturated Caprylic Caproic Laurie Myristic Palmitic Stearic Arachidic Behenic Mono-unsaturated Tetradecanoic Palmitoleic Oleic Eicosenoic Di-unsaturated Linoleic Eicosadienoic Docosadienoic Tri-unsaturated Eicosatrienoic Tetra-unsaturated Docosatetraenoic c 8 Cio C 12 C M Cl6 Ci8 C20 C22 C M C I 6 Cl8 c 20 C 2 2 ^ 2 0 C 2 2 8 7 46 15 9 2 6 1 3 5 47 15 7 2 14 1 2 42 4 42 9 0.4 18 68 12 6 3 6 60 25 20 2 24 50 6 2 25 66 M u t ~ Beef 1 T , t o n 1 tallow! L a r d tallow j 2 25 27 41 4 5 28 21 40 3 3 25 13 45 2 15 Whale 0.2 7 19 2.4 2 13 38 13 6 Her-ring 7 13 0.5 0.7 6 20 28 23 ON 4*> a > O > o < O Ä > r SOAP AND DETERGENTS 65 tion of the remainder of the fat. Since Saponification occurs only at the boundary of the initially immiscible aqueous and fatty phases, exten-sion of the interfacial boundary area by emulsification greatly pro-motes the reaction. Chemically, Saponification is a straightforward pro-cess of alkaline hydrolysis of an ester: Ch^OOCR, CH 2 OH R.COOH I I CH-OOCR 2 +3H 2 0 oHrcataiTsT CH(OH) + R 2 COOH CH 2 —OOCR3 CH 2 .OH R 3 COOH 3 RCOOH + 3 NaOH - 3 RCOONa+ 3 H 2 0 However, the physics of emulsification dominates the practical reaction rate. Some oils contain di- and poly-unsaturated acids such as linoleic acid (octadeca-8, 11 dienoic acid), linolenic acid (octadeca-8, 11, 14 trienoic acid), and similar C 2 o and C22 acids, as is shown in Table 2.1.
eBook - PDFFood Lipids
Chemistry, Nutrition, and Biotechnology, Fourth Edition
- Casimir C. Akoh(Author)
- 2017(Publication Date)
- CRC Press(Publisher)
The presence of free fatty acids may retard or completely terminate the reaction if Brønsted or Lewis acid is added as catalyst. Alcoholysis can also be carried out using glycerol as the alcohol donor with lipases or base as catalyst and this is called glycerolysis. Glycerolysis of oils is an important reaction to produce partial glycerides [39]. Monoacylglycerols and diacylglycerols are important food emulsifiers that are produced through glycerolysis reaction of oils and fats, followed by fractionation process. Recently, Guo’s research group reported the enzymatic glycerolysis of sardine oil to produce monoacylglycerols rich in ω-3 polyunsaturated fatty acids (n-3 PUFAs) [40]. In this work, they com- bined glycerolysis with molecular distillation to yield the desired monoacylglycerols. The reaction conditions used were a mole ratio of 3:1 glycerol:sardine oil, a 5% load of lipase based on the mass of total reactants, 50°C, and 2 h reaction time. In addition, when performing the reaction in larger scale in a 1 L batch reactor under 200 rpm stirring, approximately the same yields were reached. Accordingly, the work generated a scalable experimental procedure to obtain omega-3-enriched monoacylglycerols. B. INTERESTERIFICATION Interesterification is the exchanging reaction of two acyl groups between two esters [20,41]. This reversible reaction also requires a catalyst to speed up the reaction to equilibration. Interesterification is generally used to alter the melting profile of fats, crystalline characteris- tics, solid fat content, and plasticity. For triacylglycerols, interesterification can take place in an intramolecular or intermolecular mode and both modes at the same time (Scheme 2.2). The inter- esterification in the presence of an alcoholate can also generate monoalcohol esters, as in the methanolysis reaction described earlier (Scheme 2.1).
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