Twitchell process

The splitting of fats/oils can be done either in a batch (Twitchell process) or in a continuous (Colgate-Emery process) mode the enzyme-based processes are still under development for commercial applications. A comparison of these processes follows.9a,b... 

There are at least four known methods of fat splitting. These are (1) Twitchell process, (2) batch autoclave process, (3) continuous process, and (4) enzymatic process. 

Twitchell Process. The Twitchell Process (9) is one of the earliest processes developed for fat splitting. It is still used in a small way because of its low initial cost and simplicity of installation and operation. However, it is no longer of great commercial importance, due to its high-energy consumption and poor product quality. The process makes use of the Twitchell reagent and sulfuric acid to catalyze the hydrolysis. The reagent is a sulfonated mixmre of oleic or other fatty acid and naphthalene. 

Batch Autoclave Process. The batch autoclave process is the oldest commercial method used for splitting higher grade stock to produce light-colored fatty acids. It is also more rapid than the Twitchell process, taking about 6-10 h to complete. Distillation is normally performed to remove glyceride esters. 

Modifications of the old Twitchell process, which leads to production of the fatty acid itself, are also used. The fats are emulsified with sulfonic acids and heated to 100°C. Reaction is complete in two to two and a half days. The advantage of this type of hydrolysis is partly that there is no electrical barrier preventing the approach of the catalyzing ions—in fact many of these will be adsorbed at the site of reaction, i.e., at the surface of the fat droplets. 

Twitchell process. Commercial process for splitting fats to glycerol and fatty acids by heating the sulfuric acid-washed fat 20-48 hours in an open tank with steam in a mixture of 25-50% water, 0.5% sulfuric acid, and 0.75-1.25% Twitchell reagent. The original Twitchell catalyst was prepared by sulfonation of a mixture of fatty acid and benzene, but toway sulfonated petroleum products are used. 

Twitchell reagent. Catalyst for the Twitchell process (acid hydrolysis of fats). It is a sulfonated addition product of naphthalene and oleic acid, a naphthalenestearosulfonic acid. 

Tschemiac-Einhom Reaction Tschugaeff Olefin Synthesis Tsuii-Trost Reaction Twitchell Process Ugi Reaction... 

The determination of resin acids in soaps depends on the fact that fatty acids are esterified under the conditions of the experiment whilst resin acids are unaffected. Determination by the original Twitchell process has been shown to be liable to considerable error, and improvements on this method, which are also simpler in procedure, have been devised. Among them is that of McNicoll ... 

Twitchell An early process for the acid-catalyzed hydrolysis of animal and vegetable fats for the production of glycerol and soap. The catalyst was a mixture of sulfonated oleic and naphthenic acids and sulfuric acid, known as Twitchell saponifier. Invented in 1897 by E. Twitchell and commercialized by Joslin, Schmidt Company, Cincinnati, OH. The British soapmakers at that time, Joseph Crosfield Sons, did not use it because the products were considered to be too dark in color. 

TeGrotenhuis, W., Stenkamp, S. and Twitchell, A. (2005) Microreactor Technology and Process Intensification (eds Y. Wang and J.D. Holladay), American Chemical Society, Washington, DC, p. 360. 

Methyl Ester-Based Processes. The fatty methyl esters are produced predominantly by the transesterification of fats and oils with methanol in the presence of an alkaline catalyst under very mild reaction conditions.l5a,b They are used in the production of lauric-type (Cl2) alcohols. The short-chain fatty methyl esters (C8-Cl0), produced as by-products via the fractional distillation of crude lauric-type (coconut, palm kernel) methyl esters, are converted to fatty acids via acidic or alkaline hydrolysis (Fig. 36.12). The hydrolysis of short-chain fatty methyl esters by stream splitting or Twitchell-type processes is not very efficient because of unfavorable equilibrium constants.16a,b... 

A. Twitchell, in Microreactor Technology and Process Intensification, Y. Wang,... 

During the last few years, however, there has been a growing attempt to first separate the glycerol from the fatty acids, and then convert the latter into soap by treatment with the carbonates of soda or potash, which are of course considerably cheaper than the caustic alkalies, but cannot be used in the actual saponification of a neutral fat. The two processes chiefly used for this purpose are those in which the reaction is brought about by enzymes or by Twitchell s reagent. 

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