Neo acids: Synthetic highly branched organic acids

Neo acids are highly branched synthetic trialkyl acetic acids manufactured by reacting an olefin with high purity carbon monoxide under high pressure in the presence of an acidic-type catalyst. The starting olefins for neopentanoic (C₅, single isomer) and neodecanoic (C₁₀, mixed isomers) acids are isobutylene and nonene, respectively. Commercial quantities of both products have been available since 1964. Neopentanoic acid is used in the preparation of t-butyl peroxy neopentanote (pivilate), a peroxyester initiator used in polyethylene manufacture. The C₅ neo acid also finds use in a variety of other industrial end uses, e.g., pharmaceutical, agricultural chemicals, and reaction of form hindered, very stable esters. Metal salts of neodecanoic acid are used in paint driers, PVC stabilizers, and peroxyester initiators. Other reactions such as esterification, amide formation, and reaction with ethylene oxide will be discussed.     

Sulfonated branched chain fatty acids and esters

In continuation of work reported a year ago describing branched chain fatty acids, a series of monosodium methyl 2-sulfo-2-alkylalkanoates [RR'C (SO₃Na) CO₂CH₃] were synthesized. The surface active properties of these compounds were evaluated and compared with the corresponding disodium 2-sulfo-2-alkylalkanoates [RR'C (SO₃Na)CO₂Na]. Alkaline hydrolysis rates show that the sodium methyl esters are stable. Relative to the disodium salts, these compounds exhibit better wetting properties and more stable foams. Presented at the AOCS Meeting, Cincinnati, October 1965. E. Utiliz. Res. Dev. Div., ARS, USDA.     

Synthesis of alkyl‐branched fatty acids

Alkyl‐branched fatty compounds are of interest for industrial products in the cosmetics and lubricant areas. In this review, clay‐ and zeolite‐catalyzed isomerizations of unsaturated fatty compounds, especially of oleic acid, are discussed. While clay‐catalyzed reactions give most complex mixtures of dimeric fatty acids and of monomeric so‐called “isostearic acid”, the zeolite‐catalyzed process yields preferentially an isomeric mixture of isostearic acids having the methyl branch on the 8–14 positions of the alkyl chain. Synthetically useful additions of alkyl radicals can only be performed on ω‐unsaturated fatty compounds, whereas perfluoroalkyl iodides were added to fatty compounds with terminal as well as internal double bonds using electron transfer‐initiated radical addition reactions. Electrophilic additions of alkyl carbenium ions generated by decomposition of alkyl chloroformates by ethylaluminum sesquichloride give well‐defined alkyl‐branched oleochemicals with good yields.     

On the syntheses of branched saturated fatty acids

In order to investigate the relation between the structure of mono-branched saturated fatty acids and their physical properties, a three-factor central composite design was constructed. For this purpose sixteen different fatty acids were prepared. The synthetic strategy was to use if possible, a few common starting materials for the preparation of most of the acids. Thus alkylation and hydrolysis of oxazolines were used for the preparation of 2-butylhexanoic acid, 2-methyloctadecanoic acid, 2-hexadecyloctadecanoic acid and 2-pentyloctadecanoic acid. A number of acids were prepared from thiophene derivatives followed by desulfurization with Raney-Nickel alloy under alkaline conditions. Thus, starting from 3-ethylthiophene, 4-ethyl-2-thiophenecarboxylic acid and 4-ethyl-2-methyl-5-thiophenecarboxylic acid were prepared, which upon desulfurization gave the desired 4-methylhexanoic acid. From 3-bromo-2-methylthiophene, 3-ethyl-2-methyl-5-thiophenecarboxylic acid was preparedvia 3-acetyl-2-methylthiophene and 3-ethyl-2-methylthiophene. Desulfurization gave 4-ethylhexanoic acid. Another approach started with 2-acylthiophenes, which were reacted with Grignard reagent to yield the appropriate olefins. By metalation and reaction with carbon dioxide, these were transformed to the corresponding 2-thiophenecarboxylic acids. Upon desulfurization, the desired fatty acids were obtained. In this way 6-propyldecanoic acid, 6-hexyldodecanoic acid, 6-methyldodecanoic acid and 6-pentylpentadecanoic acid were prepared. The remaining four acids were prepared from some of the branched acids described above through Kolbe reactions of dioic acids. Thus 16-methyloctadecanoic acid and 10-methyl-dodecanoic acid were obtained from 4-methylhexanoic acid, 16-ethyloctadecanoic acid from 4-ethylhexanoic acid and 9-pentyloctadecanoic acid from 6-pentylpentadecanoic acid.     

Isolation and Partial Identification of Lactones from Technical Isostearic Acid

Using the techniques of clathrate formation with urea and chromatographic separation on silicagel, lactone fractions (about 6–8%) were isolated from technical isostearic acid. The lactones were partially identified (GC/MS) as a range of γ-lactones which included branched and unbranched isomers and homologs, besides other compounds. A mechanism is proposed for the formation of these lactones, relating them to the bulk of the isostearic acid isomers.     

On the syntheses of triacylglycerols from branched saturated fatty acids

A number of triacylglycerols with branched acyl groups were prepared via 1,2-isopropylidene glycerol for the purpose of studying three different physical properties: gel point, refractive index, and density. The monoacid triacylglycerols were prepared either via the corresponding acids or the acyl chlorides.     

Estolides from meadowfoam oil fatty acids and other monounsaturated fatty acids

The formation of estolides was detected during the studies on dimerization of meadowfoam oil fatty acids. By adjusting the reaction conditions, it was possible to produce monoestolides with little dimer or trimer formations. Estolides have potential use in lubricant, cosmetic and ink formulations and in plasticizers. This paper reports the conditions for production of estolides from mixed meadow-foam fatty acids, commercial oleic acid, high-oleic sun-flower oil fatty acids,cis-5,cis-13-docosadienoic acid, petroselinic acid and linoleic acid.     

Utility of branched chain carboxylic acids in the manufacture of driers

To be useful in the manufacture of driers, a carboxylic acid must yield lead, cobalt, manganese, calcium and zinc soaps which are soluble in paint vehicles and petroleum hydrocarbon thinners. The drying metal soaps of a number of saturated branched chain carboxylic acids were prepared to determine the relationship of acid structure to metal soap solubility. It was found that with the exception of 4-ethyl-5,5-dimethyl-hexanoic acid those branched chain acids containing at least six carbon atoms in the longest straight chain yielded soluble drying metal soaps and were therefore useful in drier manufacture. soluble “basic” lead soaps, pale-colored manganese soaps and reddish purple cobalt soaps were obtained from acids lacking in alpha branching. Alpha-branched acids yielded insoluble basic lead soaps, dark manganese soaps and dark blueviolet cobalt soaps.     

Minor carboxylic acids in finnish tall oil fatty acids: Aromatic,alicyclic, and branched chain aliphatic constituents

Thirteen aromatic carboxylic acids in Finnish tall oil fatty acids were identified and quantified by gas chromatography-mass spectrostereoisomeric secodehydroabeitic acids secoditerpene and dehydroabeitic acids. The other aromatic acids were various secoditerpene ando- alkyl- phenylalkanoic acids. A number of minor nonaromatic acids with mono- and bicyclic, and branched chain structures were also identified and quantified.     

Further studies of the saturated methyl branched fatty acids ofVernix caseosa lipid

By the method of capillary gas chromatography-mass spectrometry, we have identified 35 monomethyl and 46 dimethyl branched acids in the saturated acids of vernix caseosa lipid with chain lengths ranging from C₁₁ to C₁₈. Many other mono-, di-, and trimethyl branched acids have been partially identified. All methyl branches were found to be on the even numbered C-atoms except for some terminal iso methyl groups. Three types of dimethyl branched acids were found: those with a terminal iso structure, those with a terminal anteiso structure, and those with neither iso nor anteiso structures. The 4-methyl branch predominated for all types of branched acids. Equivalent chain length data for di- and trimethyl branched acids were determined on a Pentasil (nonpolar) wall coated capillary column and checked by calculation from monomethyl branched acid data. Mass spectral identification was performed with and without the aid of a data system. A possible mode of formation of these acids is discussed.     

Phospholipid studies of marine organisms: New branched fatty acids fromStrongylophora durissima

The phospholipids of the spongeStrongylophora durissima were analyzed. The major phospholipids present were phosphatidylethanolamine (PE), phosphatidylcholine (PC), phosphatidylserine (PS), phosphatidylglycerol (PG) and phosphatidylinositol (PI). The major fatty acid components of the phospholipids consisted of short chain (C₁₄−C₁₉) and very long chain (C₂₅−C₃₀) “Demospongic” acids. Three novel branched Δ⁵ monounsaturated acids,Z-19-methyl-5-pentacosenoic,Z-19-methyl-5-hexacosenoic andZ-19-methyl-5-heptacosenoic acids were encountered in the sponge. The 3-saturated counterparts of these compounds, 19-methylpentacosanoic, 19-methylhexacosanoic and 19-methylheptacosanoic acids, as well as 19-methylpentacosanoic and 20-methyloctacosanoic acids also are hitherto undescribed acids present in the sponge. Trace amounts of 2 very long chain acids also were detected and their structures tentatively assigned as 19,21-dimethylheptacosanoic and 20,22-dimethyloctacosanoic acids. The distribution of these fatty acids according to phospholipid head groups also was described.     

Characterization of branched chain fatty acids from subcutaneous triacyglycerols of barley-fed lambs

The fatty acids of subcutaneous triacylglycerols (containing ca. 11% of branched chain components) from lambs fed on barley-rich diets were fractionated by treatment with mercuric acetate and by urea adduct formation to yield concentrates rich in the branched chain components, all of which were saturated. The concentrates were subjected to analysis by high resolution gas liquid chromatography in conjunction with mass spectrometry. The branched chain fatty acids consisted of a complex mixture of mono-, di-, and trimethyl substituted components. The greater part of the mixture comprised monomethyl substituted acids of chain length 10–17 carbon atoms. Within each of these molecular species, a number of positional isomers was identified, notably in respect of methyltetradecanoic acid (methyl substituent on carbon 2, 4, 6, 8, 10, and 12) and methylhexadecanoic acid (methyl substituent on carbon 2, 4, 6, 8, 12, and 14). Homologous series also could be recognized of one of which all eight members from 4-methyldecanoic acid to 4-methylheptadecanoic acid were identified; together they accounted for ca. 39% of the branched chain fatty acids which were sampled for mass spectrometry. The dibranched acids identified consisted of five members of a homologous series, ranging in chain length from 11–15 carbon atoms and with substituent methyl groups at positions 4 and 8. Though the identity of only one tribranched acid (2,6,10-trimethyltetradecanoic acid) was established, others also apparently were present in the mixture. The probable involvement of methylmalonate in the biosynthesis of these branched chain acids is discussed briefly, with particular reference to the availability of vitamin B₁₂ in relation to the activity of methylmalonyl coenzyme A mutase.     

The relationship between the structure of monoalkyl branched saturated fatty acids and some physical properties

The gel point and the refractive index of monoalkyl branched saturated fatty acids were determined and related to the structure of the acids. A three-factor central composite face-centered design was constructed where the three variables were the length of the main chain, the branching position and the length of the side chain. Second-order models were calculated in which the two properties were related to the structure. In order to confirm the validity of the models, two additional fatty acids were analyzed. The gel point was found to be proportional to the length of the main chain and the square of the branching position whereas the refractive index was proportional to the length of both the main and the side chain and also to the square of the main chain.     

Eicosenoic acid and other fatty acids ofSapindaceae seed oils

The seed oils of 11 species ofSapindaceae were examined, and their fatty acid composition was determined.cis-11-Eicosenoic acid was identified as the major fatty acid ofKoelreuteria paniculata. It was present in nine of the 11 species in amounts from 8–60% of the total fatty acids and is evidently a common component of oils of this plant family. Arachidic acid was present in amounts up to 11%. Only three of the oils had acids of chain length greater than C-20. Seed oils of certain species ofKoelreuteria andCardiospermum are good potential sources of 11-eicosenoic acid. N.R. C. No. 9537.     

Alkane isomerization over sulfated zirconia and other solid acids

Some solid acids, including sulfated zirconia and certain industrial isomerization catalysts, catalyze two types of n-butane isomerizations, avoiding primary carbenium ions or carbonium ions: (1) an internal rearrangement of the C atoms in n-butane and (2) skeletal isomerization of n-butane to iso-butane. No superacid sites are required for these reactions. The skeletal isomerization is an intermolecular reaction, involving a C₈ intermediate. Easily accessible Brønsted acid sites and small amounts of olefin are crucial. Spectroscopic examination of the acid sites on sulfated zirconia shows that they are not stronger than the acid sites in zeolites such as HY. The butane isomerization rate is suppressed by CO, even when no CO is adsorbed on Lewis sites; formation of oxocarbenium ions is likely. The decisive role of Brønsted acid sites is demonstrated by results on deuterated catalysts.     

Fatty acids ofLindera umbellata and other Lauraceae seed oils

Seed kernel oils of seven species of Lauraceae were examined and the fatty acid composition of six of these was determined. The oil ofLindera umbellata had 4% ofcis-4-decenoic, 47% ofcis-4-dodecenoic, and 5% ofcis-4-tetradecenoic acid in the total fatty acids. Positive identification of these acids was made and new derivatives were prepared. Possible routes of biosynthesis are discussed. Oils from the other species did not contain more than a trace of unsaturated C₁₀−C₁₄ acids. Their major acids were capric and lauric with varying amounts of unsaturated C₁₈ acids. Issued as NRC No. 8928. Presented at the AOCS Meeting, Cincinnati, October 1965.     

Oxidative stability of conjugated linoleic acids relative to other polyunsaturated fatty acids

Contrary to current opinion, conjugated linoleic acids (CLA) as a mixture of several isomers have been previously shown to function as prooxidants in the form of free fatty acids and methyl esters in heated canola oil. Furthermore, CLA oxidizes considerably faster than linoleic acid. However, stability of CLA relative to other polyunsaturated fatty acids remains undetermined. The present study was therefore undertaken to examine the relative oxidation rate of CLA compared with that of linolenic acid (LNA), arachidonic acid (AA), and docosahexaenoic acid (DHA) in air at 90°C. CLA, both in the form of free fatty acids and triacylglycerols, were extremely unstable to the same extent as DHA, but they oxidized considerably faster than LNA and AA. The mechanism by which CLA were readily decomposed was probably due to formation of the unstable free-radical intermediate.     

The structures of the branched fatty acids in the wax esters of vernix caseosa

By combined gas liquid chromatography-mass spectrometry a series of monomethyl branched fatty acids was found in the fatty acid moiety of the wax esters of vernix caseosa. The methyl branch occurred on the even C-atoms of chains ranging from C₁₁ to C₁₇ (some 43 compounds in all). Except for the iso acids and possibly some of the anteiso acids, these could be formed by replacement of malonyl CoA with a molecule of methyl malonyl CoA at the point of the branch. Smaller amounts of fatty acids also were found with two methyl branches occurring on the even C-atoms of chains ranging from C₉ to C₁₅.     

Reaction of gossypol with amino acids and other amino compounds

The reactions of gossypol with certain amino acids and other amino compounds have been studied spectroscopically with respect to the effect of time and pH in the range from 5.7 to 7.5 at 37 C. The rate of reaction of gossypol with amino acids increases with increase in pH and has been shown to be related to the distance of the amino group from the carboxyl group within the molecule. Reaction products of gossypol with amino acids and other amino compounds were subjected to various purification procedures and analysis to determine combination ratios. In addition to the expected gossypol-to-amino compound ratio of 1:2, dictated by the formation of Schiff base-type bonds with the two aldehyde groups of gossypol, compounds with ratios of 1:3 and 1:4 were isolated. These results indicate that each of the two aldehyde groups of gossypol can react with two amino groups under the conditions studied. Deceased March 9, 1969.