Norman O. V. Sonntag

Glycerolysis of fats and methyl esters — Status, review and critique

With the possible exception of catalytic hydrogenation, perhaps no unit operation within the realm of oleochemistry is as thoroughly complex as that of glycerolysis. Among the misconceptions and half-truths that prevail concerning the glycerolysis of fats are the notions that it involves a strictly random distribution of acyl groups among all of the available hydroxyl groups, that the solubility of glycerol in the fat at the reaction temperature determines the yield of monoglyceride that may be obtained, that the advantageous effects of the Law of Mass Action can be realized only when the reaction media is in ultimate homogeneity, in other words, complete mutual solubility, and, more importantly, that there is an equivalence of emulsification properties for the chief products of glycerolysis, i.e., the α-and β-monoglycerides, in both food and industrial emulsification. Numerous examples from international literature establish the limitations which prevail in temperature, agitation and use of excess of glycerol in batch glycerolysis reactions, but the practical limits for glycerolysis undersuperemulsification conditions remain to be established. The disadvantages of glycerolysis in homogeneous solvents still are insufficient to justify the use of those that are available, but the use of both pressure and gaseous catalysts such as carbon dioxide appear to offer the greatest hope for improvement in yields. Substantial energy savings may dictate the choice of methyl ester glycerolysis processing for future plants, especially those in the international sphere. Pros and cons of monoglyceride analytical methodology are evaluated.

New developments in the fatty acid industry in America

Although acquisition, divestiture and other organizational changes within the American oleochemical industry are still the most startling and attention-attracting, the development of new technology continues to be of paramount scientific interest. Noteworthy among the new developments are (a) the continuing development of new vegetable oil raw materials like 90% erucic acid rapeseed oil and 80% oleic acid sunflower; (b) the intense process development under way in some areas for the minimization of thermal energy requirements of certain reactions like polymerization (dimer acids), glycerolysis (mono- and diglycerides) and fat splitting; (c) the ever-increasing substitution of methyl esters for fatty acids in the production of a whole series of oleochemicals; (d) development of new esterification catalysts; (e) lipase catalysis of interesterification; (f) development of new corrosion-resistant materials of construction; (g) the use of irradition sulfoxylation as a preferred production route to randomly sulfonated methyl esters; and (h) superemulsification as an aid to hydrophobic/hydrophilic liquid chemical reactions. Continued attention to alternative feedstocks, biotechnology, microprocessor technology, pollution control and lower energy consumption are certain to receive considerable attention for the next several years.

Growth potential for soybean oil products as industrial materials

Crude soybean oil, as a major source of edible oil for the world, is available on such a scale that it serves additionally as the origin for many industrial applications and for such materials as phospholipids (lecithins, cephalins), tocopherols (for vitamin E), sterols (for pharmaceuticals) and recovered fatty acids from acidulated soapstocks. The latter always have offered the oleochemicals manufacturer a low cost source of valuable fatty acids, and soybean oil itself, after hydrogenation, serves as the most readily available, lowest cost source of 90% stearic acid from among all fats and oils. As an alternative to alkali refining and the soapstock produced, physical refining of the degummed soybean oil is a potential source for fatty acids and for recovery of larger amounts of valuable sterols and tocopherols, but this process severely degrades the oxidation stability of the fatty acids.The largest potentials for growth in industrial applications are for soybean oil itself in pesticide dispersion and grain dust control; triglycerides and fatty acids split therefrom for 90% stearate oleochemicals and selected food additivies; fatty acids from soapstocks up-graded medium-grade oleochemicals, medium-grade soaps for industrial cleaning operations, and in animal feeds and pet foods; phospholipid gums in fractionated and modified lecithins and cephalins; soy deodorizer distillates containing α-to copherol (vitamin E) and sterol-derived sex hormones. Inclusion of food additives, feed and pet food additives with the more usual industrial markets results in the conclusion that industrial utilization of soybean oil could reach 12% of total consumption in the U.S. within five years.

Reactions of fatty acid chlorides. I. Preparation of fatty acid anhydrides

The anhydrides of decanoic, lauric, myristic, palmitic, stearic, and oleic acids have been prepared in better than 90% yields through the corresponding acid chlorides with acetic anhydride. Oleic anhydride could only be prepared satisfactorily when oleoyl chloride was prepared, in turn, with oxalyl chloride. A comparison has been made of the various synthetic methods.

Current future fat-based raw materials for soap manufacture

The traditional use of coconut and palm oils for soap manufacture can be expected to continue indefinately. Certain oils of the oleic/ linoleic acid group are too unsaturated to yield soaps of the desired degree of hardness and stability. They may be hydrogenated to form suitable hard soap fats; a quantity of these oils is used regularly in the preparation of soft soaps and in blends with harder fats. The chief animal fat used in soapmaking is tallow. Other fats and oils less frequently used include babassu, palm kernel and olive oil. The ratio of tallow/coconut oil used for the manufacture of toilet soaps ranges from 85:15 to 75:25. A correlation of soap properties with the ratio of 95:5 to 75:25 of tallow and coconut oil demonstrates that properties such as cracking, swelling and hardness are not as sensitive to the changes in the blend ratios as are erosion characteristics, slushing and lather. Present production of Russian and Eastern European soap is from huge quantities of straight-chain, odd- and even-numbered, carbon saturated synthetic fatty acids (SFA). Future fat-based raw materials might include certain fractionated fatty acids, methyl ester intermediates, acidulated sunflower and/or safflower soapstocks. Jojoba wax might be a surprising new raw material.

Reactions of fatty acid chlorides: II. Synthesis of monohydrazides or dihydrazides by acylation of hydrazine hydrate with saturated fatty acid chlorides

The acylation of hydrazine hydrate with a series of saturated fatty acid chlorides containing from eight to 18 carbon atoms was studied under a variety of conditions in order to obtain the desirable fatty acid monohydrazides. Optimum yields were obtained (ranging from 31.5% to 75% as the series ascended from C-8 to C-18) for the even-numbered monohydrazide members through the use of a large excess of hydrazine hydrate in several organic solvents. Diethyl ether was found to be suitable if the acid chloride is dissolved in it and added slowly to a cold mixture of hydrazine hydrate in ether. The Schotten-Baumann technique was found suitable for the preparation of the symmetrically substituted fatty acid dihydrazides in better than 82% yields when one mole of hydrazine hydrate was acylated with two of acid chlorides. Physical and chemical properties of both series of fatty nitrogen derivatives are briefly treated. Stearic monohydrazide was condensed with acetonylacetone to give a substituted pyrrole. An unsymmetrical dihydrazide was prepared by the acylation of myristic monohydrazide with lauroyl chloride. Stearic dimethylhydrazide was prepared by the acylation of dimethylhydrazine with stearoyl chloride. Two quaternizations of this product were carried out.

Straight-chain fatty acids from alcohols, olefins, and ziegler intermediates

Six synthetic routes to straight-chain saturated fatty acids other than from saturated hydrocarbons currently in research and development within the petrochemical industry are discussed and evaluated and the prospects for each reviewed in the light of advantages and disadvantages for each.

New developments in synthetic fatty acids

New developments in synthetic fatty acids have occurred in the last few years in Russia, Japan, the United States and Canada. In 1959 Russia decided to replace 40% of natural fatty acids in soaps with synthetic fatty acids. In 1966, 548 million pounds of C5–C30 synthetic fatty acids were produced including 288 million pounds of C10–C20 fatty acids. Forty million pounds of fatty acids are converted directly to the fatty alcohols for detergent use. A conservative estimate predicts that one billion pounds of synthetic fatty acids will be produced in Russia by the end of the current five-year program. Reports say that the Japanese have been interested in the oxidation of not only paraffin hydrocarbons but naphthenic petroleum hydrocarbons as well. Production of lower homology fatty acids up to butyric acid is being seriously considered in Japan. In America the most likely syntheses aside from “oxo” syntheses being considered for the manufacture of products like lauric acid is the carboxylation of the Ziegler intermediates prepared from ethylene polymerization. Some data on the current and future coconut oil consumption by major end-use for Canada and the United States are presented. Synthetic lauric acid is predicted for 1970 in the United States.