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. Prepared from an address given at a meeting of the Northeast Section, New York, June 1968.     

Synthetic fatty acids in Eastern Europe

For over a century various investigators have studied the air oxidation of paraffinic hydrocarbons to produce synthetic fatty acids. Today in the socialistic countries there are six to eight plants manufacturing these acids to replace in soaps tallow fatty acids which are needed as a source of food. The principal technological advances in air oxidation, prior to World War II, were made by Germany while more recently Russia and its satellite countries have made the major contributions. Although the oxidation involves a multitude of chemical reactions taking place consecutively and simultaneously, it has been fairly well established that the alkylhydroperoxide precursors are converted to alcohols and then further oxidized to carboxylic acids. The cost of manufacturing synthetic fatty acids in Eastern Europe ranges between 8–12￠ per pound depending upon the raw material, processing costs and by-products.     

Historical and marketing trends of natural/synthetic fatty acids

As long as a substantial portion of raw materials for natural fatty acids are relatively inexpensive by-products of other major industries, natural fatty acids should fulfill the world's projected needs at least through 1985. Production of synthetic fatty acids may also increase; however, at the present time the cost of their raw material and processing has made them largely noncompetitive, except in a few cases. Synthetic organic acid manufacturers currently supplying short chain products will continue their efforts to enter the detergent range fatty acid market area. We expect some breakthrough in synthetics during the life of our forecast. However, potential producers have yet to develop an economically competitive synthetic fatty acid as a replacement for natural fatty acids in the U.S. Petroleum-based products include odd, even, and branched chain acids whose performance must be proven. Finally, the petroleum base for synthetic fatty acids no longer has the price stability we have been accustomed to in the past. Recent changes in price of ethylene and forecasts are evidence of this trends for the future.     

Industrial chemical uses of polyunsaturated fatty acids

Production of vegetable, animal and marine oils containing more than about 40% unsaturated fatty acids totaled 15,000 million pounds in 1968, almost on the scale of petrochemical production. The greater share (64%) of this nonfossil oil production was directed toward food uses, the remainder toward industrial and animal feed uses. The variety of chemical reactions carried out on these unsaturated fatty acid products include hydrogenation, interesterification, dimerization, sulfation, formation of nitrogen compounds, epoxidation, alkaline cleavage and oxidative ozonolysis. Some of these reactions have been developed at Utilization Research and Development Divisions of the Agricultural Research Service, U.S. Department of Agriculture. Research is continuing in developing new reactions for potential industrial application. An example is reductive ozonolysis of unsaturated fatty esters to produce monofunctional aldehydes and bifunctional aldehyde esters. Presented at the ISF-AOCS World Congress, Chicago, September 1970. No. Market. Nutr. Res. Div., ARS, USDA.     

Fermentation of long chain compounds byTorulopsis magnoliae III. Preparation of dicarboxylic acids from hydroxy fatty acid sophorosides

Conversion of hydroxy fatty acids, prepared from the products of fermentation of long chain hydrocarbons or fatty acids withTorulopsis magnoliae, to dicarboxylic acids with 15 to 18 carbon atoms is described. Both nitric acid oxidation and fission in 85% KOH give yields of 60–75%, but the products have different compositions. The nature of the compound fermented determines the composition of the hydroxy acids produced and hence that of the derived dicarboxylic acids. A convenient method is presented for hydrolysis of the hydroxy fatty acid sophorosides obtained by fermentation. Presented at the AOCS Meeting in Toronto, 1962, Issued as NRC No. 8900.     

Tall oil fatty acids

About 1949, with the advent of effective fractional distillation, the tall oil industry came of age, and tall oil fatty acids (TOFA), generally any product containing 90% or more fatty acids and 10% or less of rosin, have grown in annual volume ever since, until they amount to 398.8 million pounds annual production in the U.S. in 1978. Crude tall oil is a byproduct of the Kraft process for producing wood pulp from pine wood. Crude tall oil is about 50% fatty acids and 40% rosin acids, the remainder unsaps and residues; actually, a national average recovery of about 1–2% of tall oil is obtained from wood. On a pulp basis, each ton of pulp affords 140–220 pounds black liquor soaps, which yields 70–110 pounds crude tall oil, yielding 30–50 pounds of TOFA. Separative and upgrading technology involves: (a) recovery of the tall oil; (b) acid refining; (c) fractionation of tall oil; and occasionally (d) conversion to derivatives. TOFA of good quality and color of Gardner 2 corresponds to above 97% fatty acids with the composition of 1.6% palmitic & stearic acid, 49.3% oleic acid, 45.1% linoleic acid, 1.1% miscellaneous acids, 1.2% rosin acids, and 1.7% unsaponifiables.     

Geochemistry of lipids

Lipids, particularly the glycerides, terpenes, sterols, and hydrocarbons, have properties conducive to their preservation either in original or transformed state and are significant constitutents of the geochemical biomass. The occurrence of phytane, pristane, and fatty acids in Precambrian sedimentary rocks 2.7 billion years old has been interpreted to indicate the existence of life processes similar to those that are operative today. The stability of lipids is highly variable. Sterols, terpenes, fatty acids, esters, and hydrocarbons have been isolated from ancient sedimentary rocks; there is evidence, however, that esters may hydrolyze. Under certain conditions, highly unsaturated fatty acids may undergo combined biochemical and chemical transformations that lead to the formation of petroleum hydrocarbons. Lipids found in geological environments are derived from contributing organisms, which represent specific ecologies. Study of the ultimate products derived from these lipids permits an understanding of the geochemical environments in which they were produced, and of the transformations that occurred. Publication authorized by the Director, U.S. Geological Survey.     

How can we genetically engineer oilseed crops to produce high levels of medium‐chain fatty acids?

The end products of fatty acid synthase activities are usually 16‐ and 18‐carbon fatty acids. There are however, several plant species that store 8‐ to 14‐carbon (medium‐chain) fatty acids in their oil seeds. Among the medium‐chain fatty acids (MCFA), caprylic (8:0) and capric (10:0) are minor components of coconut oil, which are used in many industrial, nutritional and pharmaceutical products. Engineering crop plants such as Brassica could provide an economical source of these oils. During the last decade many laboratories have identified, cloned and characterized both the biosynthetic and catabolic enzymes regulating the composition and levels of these unusual fatty acids in seed oil. Among the biosynthetic enzymes thioesterases (TE), β‐ketoacyl‐ACP synthases (KAS) and acyltransferases are best characterized. In fact several independent investigators have shown that combined expression of the medium‐chain specific enzymes, specifically, TE, KAS and lysophosphatidic acid acyltransferase (LPAAT) results in the production of significant levels of MCFA in seed that otherwise do not accumulate any medium‐chain fatty acid. However, any additional increase in the levels of MCFA in transgenic seeds will require further detailed studies, such as possible induction of the medium‐chain specific enzymes in β‐oxidation and the glyoxylate pathways. To examine such a possibility, a number of genes involved in the β‐oxidation cycle among them a novel enzyme now designated as ACX3, a medium‐chain specific acyl‐CoA‐oxidase, has also been cloned. This article is an attempt to summarize our current knowledge and the present status of engineering oilseed crops for production of medium‐chain fatty acids.     

Vegetable oil raw materials

Vegetable oils that are important to the chemical industry include both edible and industrial oils, which contribute 24% and 13.5%, respectively, compared to 55% for tallow, to the preparation of surfactants, coatings, plasticizers, and other products based on fats and oils. Not only the oils themselves but also the fatty acids recovered from soapstock represent a several billion pound resource. Coconut oil is imported to the extent of 700-1,000 million pounds per year. Its uses are divided about equally between edible and industrial applications. Safflower oil has a relatively small production, but 15–25% of the oil goes into industrial products. Soybean oil, the major edible oil of the world, is produced in the United States at the rate of 11,000 million pounds per year with more than 500 million pounds going into industrial uses, representing 5% of the total production. Castor oil is imported to the extent of about 100 million pounds per year. Linseed oil production has declined drastically over the last 25 years but still amounts to about 100 million pounds per year. Oiticica and tung oils are imported in lesser amounts than castor and linseed oils. New crops that have industrial potential, as well as the traditional vegetable oil crops, include seed oils from crambe,Limnanthes, Lesquerella, Dimorphotheca, Vernonia, andCuphea plants. Crambe oil contains up to 65% erucic acid. Oil fromLimnanthes contains more than 95% of fatty acids above C₁₈.Lesquerella oil contains hydroxy unsaturated acids resembling ricinoleic acid from castor oil.Dimorphotheca oil contains a conjugated dienol system.Vernonia oils contain as much as 80% epoxy acids. TheCuphea oils contain a number of short chain fatty acids. Of these, crambe,Limnanthes, andVernonia are probably the most developed agronomically. Competition between vegetable oils and petrochemicals for the traditional fats and oil markets has been marked over the past 25 years, but prices for petrochemicals have accelerated at a greater rate than those for vegetable oils; and, it is now appropriate to reexamine the old as well as the new markets for fatty acids.     

Untersuchungen über die Entstehung von Kohlenwasserstoffen in erhitzten gesättigten Fettsäuren und Fettsäureestern

Studies on the Formation of Hydrocarbons in Fatty Acids and Fatty Acid Esters on Heating The investigations on the volatile compounds of the unsaponifiable matter and the steam distillate of heated saturated fatty acids have shown that on heating in the presence of air, along with other substances, hydrocarbons having a chain length 1 to 2 C atoms shorter than the corresponding fatty acids are formed. The splitting proceeds so slowly in the case of esters that even after 4 hrs of heating at 160°C no reaction products could be detected. By heating palmitic acid under the same conditions, except that vacuum was employed, no perceptible quantities of hydrocarbons were found.     

Oxidation of Branched Chain Fatty Acids by Chromic Acid

The kinetics of oxidation of isobutyric and isovaleric acids by chromic acid in sulphuric acid medium have been studied. The end product acetic acid is supposed to be derived from the ketones which are the initial oxidation products of the corresponding branched chain fatty acids. The influence of acetic acid on the oxidation velocity has been examined and a marked effect on the rate constants with increasing acetic acid concentration has been observed. A mechanism involving the electrophilic attack of the oxidant on the tertiary carbon atom of the fatty acid to yield a carbonium ion has been postulated.     

Measurement of the metabolic interconversion of deuterium-labeled fatty acids by gas chromatography/mass spectrometry

An analytical method that was developed to analyze deuterium-labeled fatty acids in human blood has been extended to identify labeled fatty acids from C₁₄ to C₂₄ chain length which are formed by metabolic processes such as desaturation, elongation, or shortening of the labeled fatty acids fed. A new computer and a hard-wave adder have been utilized to assure reliable data acquisition. Relative standard derivations for the analysis of labeled fatty acids were measured at 0.02, 0.03, and 0.04 at the 5%, 1%, and 0.2% levels of the labeled fatty acid methyl esters, respectively. The method makes extensive use of standards and computer processing for accuracy and high productivity. Data from a chylomicron triacylglycerol fraction are included to demonstrate the sensitivity of detection of metabolites formed by desaturation and elongation. The mention of firm names or trade products does not imply that they are endorsed or recommended by the U.S. Department of Agriculture over other firms or similar products not mentioned.     

Oxidative decarboxylation of unsaturated fatty acids

Long‐chain internal olefins were prepared by silver(II)‐catalyzed oxidative decarboxylation of unsaturated fatty acids by sodium peroxydisulfate. Similar to saturated carboxylic acids, 1‐alkenes were the major decarboxylation product in the additional presence of copper(II), whereas in the absence of copper(II) alkanes were predominantly formed. In both cases, the internal unsaturation of the fatty acids remained largely intact, although the moderate yields indicated that side reactions occurred to a significant extent. The simple procedure makes this multistep one‐pot reaction useful for the synthesis of a variety of internally unsaturated hydrocarbons. The purified products, almost all of which are prepared for the first time, may serve as reference compounds for studies on the heterogeneously catalyzed decarboxylation of triglycerides and fatty acids in the absence of hydrogen. Practical applications: The products of the chemistry described in this contribution, i.e., unsaturated long‐chain hydrocarbons, provide bio‐based building blocks for further chemical modification toward products which may be applied as (bio)fuels, lubricants, solvents, and polymeric materials.     

Fatty alcohols

“Fatty” or higher alcohols are mostly C₁₁ to C₂₀ monohydric compounds. In probably no other homologous aliphatic series is the current balance between natural and synthetic products so vividly evident. Natural sources, such as plant or animal esters (waxes), can be made to yield straight chain (normal) alcohols with a terminal (primary) hydroxyl, along with varying degrees of unsaturation. In the past, socalled fatty alcohols were prepared commercially by three general processes from fatty acids or methyl esters, occasionally triglycerides. Fatty acids add hydrogen in the carboxyl group to form fatty alcohols when treated with hydrogen under high pressure and suitable metal catalysts. By a similar reaction, fatty alcohols are prepared by the hydrogenation of glycerides or methyl esters. Fatty alcohols are also prepared by the sodium reduction of esters of fatty acids in a lower molecular weight alcohol. The sodium reduction method was ordinarily too expensive; it was displaced early by the other methods; finally most unsaturated alcohols made by this route were largely replaced. Methyl ester reduction continues to provide perhaps 20% of the saturated fatty alcohols, and selective hydrogenation with the use of special catalysts such as copper or cadmium oxides was developed for the production of oleyl alcohol. Synthetic or petroleum technology for long chain alcohols include the Ziegler process, useful for straight chain, even-numbered saturated products. A second is the carbonylation and reduction of olefins affording medium or highly branched chain alcohols. Paraffin oxidation affords mixed primary alcohols. Fatty alcohols undergo the usual reactions of alcohols. They may be reacted with ethylene oxide to yield a series of polymeric polyoxyethylene alcohols or with acetylene under pressure to yield vinyl ethers or with vinyl acetate to give vinyl ethers.     

Thermal behavior of prospective hydroxy acid grease thickeners

Melting points and heats of fusion were determined for 13 hydroxy acids and their lithium salts with chain lengths ranging from 14 to 24 carbons. Included were hydroxy acids prepared from two unusual plant sources,Lesquerella sp. andCrambe abyssinica. Upper melting point temperatures, transition entropies, and heat capacity changes of the lithium salts on heating and cooling suggest that many of the salts, particularly those of 14-hydroxyeicosanoic and 9(10)-hydroxystearic acids, would perform satisfactorily as gelling agents in the production of lubricating greases. The mention of firm names or trade products does not imply that they are endorsed or recommended by the U.S. Department of Agriculture over other firms or similar products not mentioned. metal salts of unsubstituted fatty acids, which also can serve as grease thickeners.     

Background,importance and production volumes

The importance of the fatty acid industry today is reflected by the estimated 1978 production in the U.S. of 956 M lbs., exclusive of tall oil fatty acids. The 1978 U.S. production of various fatty acids as reported monthly and annually by the FAPC of SDA, is broken down into 9 saturated categories, and 5 unsaturated categories, as follows: (1) stearic and 127.2 M lbs. (13.3%); (2) hydrogenated animal and vegetable acids (2a) 97.3 M lbs. (10.2%), (2b) 158 M lbs. (16.5%), (2c) 32 M lbs. (3.4%); (3) high palmitic, 14.6 M lbs. (1.5%); (4) hydrogenated fish, 6.5 M lbs. (0.7%); (5) lauric acid types, 88.8 M lbs. (9.3%); (6) fractionated fatty acids, (6a) C₁₀ or lower, 18.5 M lbs. (1.9%), (6b) C₁₂ and C₁₄ 55% 17 M lbs. (1.9%); (7) oleic acid, 158.3 M lbs. (16.6%); (8) animal fatty acids other than oleic, 156.3 M lbs. (16.3%); (9) vegetable or marine fatty acids, 0.1 M lbs. (less than 1%); (10) unsaturated fatty acids, 57 M lbs. (6.0%); (11) unsaturated fatty acids I.V. over 130, 24.2 M lbs (2.5%). Reported 1977 fatty acid derivative production from fatty acids (not fats and oils) is 1,980 M lbs. The average price of fatty acids has increased from 23￠/lb.. to 60￠/lb. within the last 5 years.     

Deno's oxidation — analysis of oxidation products from model compounds

Oxidations by pertrifluoroacetic acid (CF₃COOHH₂0₂H₂S0₄) have been used for possible determination of coal structure. Before applying the method to study heavy residues of coal liquefaction, the procedure has been applied to different compounds: diphenyl ethane, ∝-phenylpropionic acid, diacids and long chain fatty acids. The acids were chosen because they are expected products from coal oxidation. Their stability against the procedure was therefore tested. The oxidation products obtained were analysed by g.c. or g.c.—m.s. coupling. The study showed that the oxidation method could not be easily applied to structure determination.     

Economics of sunflower oil production and use in the United States

U.S. consumption of fats and oils over the past decade increased at an annual rate of 2.8% and in 1970 reached an all-time high of 18 billion pounds. About two thirds of U.S. consumption is in food products. Salad and cooking oils, shortening, and margarine account for the major share of food oil use. Sunflower oil is well suited for these uses especially for salad and cooking oils, and margarine, owing to its stable qualities and high ratio of polyunsaturated fatty acids to saturated fatty acids. With yields averaging around 1250 lb./acre and prices at 3–4 cents/lb., sunflowers have not been competitive with established crops in the southern states during the past few years. Returns from sun-flowers in the Red River Valley, where yields have averaged around 1000 lb, appear to be more competitive with established crops than in the southern states. Some farmers in the South have achieved yields of 2000 lb. or more per acre and this seems to indicate that yields could be improved with better management. This analysis indicates that yields of 1600–2000 lb./acre, at a price of 4 cents/lb. for the seed, should permit sunflowers to compete with corn, soybeans, wheat and sorghum in a number of farming areas. As experience is gained in growing the crop and higher yielding hybrid seed is better adapted to the available region, sunflowers should become a more significant factor in the U.S. farm economy.     

Thermal oxidation of synthetic triglycerides. II. Analysis of the volatile condensable and noncondensable phases

Tripalmitin, 1-lauryl dipalmitin, 2-lauryl dipalmitin, 1-oleyl dipalmitin and 2-oleyl dipalmitin were subjected to thermal oxidation at 200 C in the presence of air. The volatile consensable products of oxidation collected after 3 and 24 hours were analyzed for carbonyl and carboxyl compounds. The volatile non-condensable products were quantitatively examined for carbon monoxide, carbon dioxide, and hydrogen. The results indicated that long chain carbonyls were formed in the initial stages of oxidation. When the oxidation was allowed to proceed for 24 hours, saturated aldehydes from C₁ to C₁₆, methyl ketones, and other ketones were found in the volatile oxidation products. A variety of fatty acids from C₄ to C₁₆ were identified in the volatile fatty acids. The presence of dicarboxylic acids indicated that oxygen attacked the double bond of oleic acid in 1-oleyl dipalmitin. Possible mechanisms for the formation of the decomposition products were discussed. Portion of a thesis presented by Joseph G. Endres as partial fulfillment of the requirements for the degree of Doctor of Philosophy in Food Technology. Funds for the partial support of these studies were made available by the National Institute of health Grant A-1671.     

Metabolic engineering of 2‐pentanone synthesis in Escherichia coli

Expanding the chemical diversity of microbial fermentation products enables green production of fuel, chemicals, and pharmaceuticals. In recent years, coenzyme A (CoA) dependent chain elongation, resembling the reversed β‐oxidation pathway, has attracted interest for its use in producing higher alcohols, fatty acids, and polyhydroxyalkanoate. To expand the chemical diversity of this pathway, we metabolically engineered Escherichia coli to produce 2‐pentanone, which is not a natural fermentation product of E. coli. We describe the first demonstration of 2‐pentanone synthesis in E. coli by coupling the CoA‐dependent chain elongation with the acetone production pathway. By bioprospecting for enzymes capable of efficient hydrolysis of 3‐keto‐hexanoyl‐CoA, production of 2‐pentanone increased 20 fold, reaching a titer of 240 mg/L. © 2013 American Institute of Chemical Engineers AIChE J, 59: 3167–3175, 2013