Isolation of two nitrogen-free toxins from tung kernels

Summary A procedure is described for isolating two nitrogen-free toxins from tung kernels and from press cake. Chick-feeding tests were used to determine which fraction was toxic at every separation. Both substances were highly toxic as 10-mg. doses killed 4-day old chicks. These substances were shown by chromatography on glass paper to be different and chromatography homogeneous, but also unstable. The elementary composition, hydroxyl content, saponification value, and specific rotation for the two toxins are given. One of the laboratories of the Southern Utilization Research and Development Division, Agricultural Research Service, U, S. Department of Agriculture.     

Chemical and physical characteristics and possible configuration of toxins from tung kernels

Based on limited chemical and physical data, including the infrared and ultraviolet spectra of the toxins and their saponification products, it is suggested that Tung Toxin I and Tung Toxin II are diesters of a 2,3-unsaturated-5-keto acid, a polyhydroxy acid and a 3,4-unsaturated-5-keto tertiary alcohol. The 2,3-unsaturated-5-keto acid is assumed to be in equilibrium with its enol tautomer, the keto form possessing a conjugated diene and the enol form a conjugated triene structure. The polyhydroxy acid is probably very similar to gluconic acid.     

The rate of development of acidity in stored tung seeds and kernels

Summary Whole tung seeds, whole kernels, and chopped kernels of high, medium, and low moisture contents were sealed in tin cans and stored in incubators maintained at 25°, 31°, and 38°C. At intervals samples were removed and the acid value of the oil determined. The different temperatures used had slight effect on the rate of development of free fatty acids in the oil of the whole seeds and kernels, but the higher temperatures greatly increased the rate of development of free acid in the chopped kernels. Whole seeds containing 7% and 12% moisture were stored for 4 weeks and seeds containing 17% moisture were stored for 2 weeks, during which periods the oils developed free fatty acids equivalent to acid values of 2.0 or less. Under none of the conditions used did the acid values of the oils exceed 8.0 after storage for 13 weeks. Whole kernels developed even less free fatty acids than seeds stored under similar conditions. Kernels containing 4% and 6% moisture were stored for 12 weeks during which period the acid value of the oil never exceeded 1.5. Even in kernels containing 12% moisture the acid value of the oil did not exceed 6.0 at the end of 12 weeks. Chopped kernels with moisture contents of 5% and 7% could be stored for 12 days without developing an acid value in the oil of more than 8.0. However chopped-kernels with a moisture content of 12% developed an acid value in the oil in excess of 8.0 in less than a week. Whole seeds with as much as 15% moisture could probably be stored for several weeks without developing an objectionable amount of free fatty acids. Since commercial hulled “nuts” practically always contain some broken kernels, to avoid development of free fatty acids in storage they should be dried to 10% or less moisture before storage. One of the laboratories of the Bureau of Agricultural and Industrial Chemistry, Agricultural Research Administration, U. S. Department of Agriculture.     

The detoxication of tung meal

Journal of the American Oil Chemists' Society -     

The analysis of tung fruit

Methods applicable to the routine analysis of tung fruits were developed by taking into account such factors as variation in moisture content of individual fruit, high oil content of the tung kernels and the high reactivity of the extracted oil. It was found that in a closed container the moisture distributes itself evenly between individual fruits, that the oil can be extracted completely from tung kernels if they are reground with sand, and that the moisture can be removed from ground tung kernels and the solvent completely removed from the extracted tung oil without deterioration in a vacuum oven at 100° C. with 28–29 inches vacuum. Contribution No. 151 from the Carbohydrate Research Division, Bureau of Chemistry and Soils, U. S. Dept. of Agriculture.     

The domestic tung industry today

The tung tree (Aleurites fordii) requires a moderately acid soil, an annual rainfall of 45 to 70 in., and a long hot summer, yet it must have a period of cold weather in winter. These factors limit its culture in North America to a narrow belt along the Gulf of Mexico from Florida to Texas. The majority of the orchards presently consist of miscellaneous seedlings that are about 30 years of age. By replacing these with orchards of new varieties, on suitable soil, and by following recommended practices, growers can produce oil at lower costs than previously. However, crop loss from frost is still a serious problem. Machine harvesting is now a reality. During World War II the government requisitioned the entire domestic production of tung oil for military purposes, and regular customers had to turn to other products. This market has not yet been fully won back, and growers look to utilization research to improve the market.     

The characteristics of domestic tung oils

Conclusion Domestic tung oil is a very uniform product as shown by the determination of the chemical and physical properties of 74 samples taken over three successive milling seasons. The refractive index, refractive dispersion, and heat test are correlated with the total eleostearic acid content, the correlation coefficients being 0.69, 0.73, and −0.62 respectively, which indicates that any one of these values can be taken as a rough measure of the elostearic acid content. The correlation of the eleostearic acid content with the Wijs and hydrogen iodine values was lower, 0.48 and 0.53, respectively. A correlation of −0.81 was found between refractive index and heat test. One of the laboratories of the Southern Utilization Research Branch, Agricultural Research Service, U. S. Department of Agrculture.     

The performance of biodegradable tung oil coatings

Using immersion tests, viscosity measurements, FTIR and SEM, as well as biodegradation tests, biodegradable tung oil coatings were investigated. Results showed that the curing times for different formulae decreased as the amount of catalyst increased. During the curing process, there was an initial induction period where the viscosity remained more or less the same, and after a certain time, a sharp increase in viscosity was observed. The steady viscosity increased with time, revealing a continuous autoxidation process. Microorganisms in the soil attacked the surfaces of the tung oil films either uniformly on the whole plate or at specific weak points, leading to decreased volume, blurring of the small humps as well as holes. The weak point on the crosslinked chain was located at the carbonyl-containing groups, where chemical biodegradation occurred more easily and faster.     

The fatty acids of dormant tung buds

Conclusions and Summary The methyl esters of the fatty acids in the wax of dormant tung buds were prepared and fractionated in a column packed with a spiral screen. Myristic, palmitic, linoleic, oleic, and stearic acids were identified in some of the fractions by the saponification equivalents and by the melting points of the p-bromophenacyl derivatives of the saturated acids and the hydroxy derivatives of the unsaturated acids. The identification of these acids proved the presence of some of the higher fatty acid radicals similar to those found in Crisco and lanolin. It is believed that the mutual solubility of these fatty acids may have facilitated penetration of the alpha-naphthalenacetic or indole-3-acetic acid in Crisco and lanolin emulsions, into the bud tissue and in this way increased their effectiveness in prolonging dormancy. Associate chemist (resigned) and associate plant physiologist, respectively, Division of Fruit and Vegetable Crops and Diseases, Bureau of Plant Industry, Soils, and Agricultural Engineering, Agricultural Research Administration, United States Department of Agriculture     

The determination of moisture in tung fruit

Summary and Conclusions Six methods for determining moisture in tung fruit and seeds were compared. The highest moisture values, and probably those most reliable, were obtained by drying the ground tung fruit in the vaccuum oven at 101°C. for 2.5 hours under 12-mm. pressure, and by the Karl Fischer titration method. In using the Karl Fischer method on tung products, the sample must be digested in methanol at 60°C. Of these two methods the vacuum oven method is simpler and generally preferable. Somewhat lower moisture values were obtained by the forced draft oven and toluene-distillation methods. The results obtained in the forced draft oven method were low because of oxidation of the oil in the samples. One hour at 101°C. in the forced draft oven seems to be the optimum time for moisture determination, and no appreciable error in the oil content results from using the percentages of moisture so determined to calculate the oil content to basis of sample as received. For routine analysis, heating the ground tung fruit sample in a hot air blower for 15 minutes at 126.7°C. (260°F.) and adding a correction of 1.35% to the percentage of moisture obtained gives sufficiently accurate values for factory control purposes. The radio frequency meter gave values close to those obtained in the vaccum oven method against which it was standardized. It was necessary to standardize the meter separately for fruit, seeds, and kernels. In practice many samples of wet fruit would be encountered which would exceed the range of the particular instrument used. Presented at the 18th Annual Meeting of the American Tung Oil Association, Biloxi, Miss., Oct. 11–12, 1951. One of the laboratories of the Bureau of Agricultural and Industrial Chemistry, Agricultural Research, U. S. Department of Agriculture     

Studies in the expression of oil from tung fruit

Summary 1. Tests indicated that best results in yield of crude and filtered oil by an expression procedure are obtained with a tung meal containing 4.2% moisture and 20% shell. 2. The drying of tung meal using an initial air temperature of 320° F. appeared to adversely affect the yield of filtered oil from the expeller process. 3. A filtration test was developed for determining the amount of foots in a crude tung oil. 4. It was found difficult to obtain efficient oil expression from tung meals containing filter cake; in one test with this material the resulting press cake was high in oil content, while in another test the crude tung oil contained about twice as much foots material as was present in crude tung oil from tung meal containing no filter cake. 5. The expression of tung oil from a tung meal consisting of ground old tung kernels and tung shell was found difficult if not impossible. This difficulty appeared to be due, at least partly, to the fact that the meal from old kernels will not plasticize when subjected to heat and pressure. When these kernels were mixed with new kernels no difficulty was experienced in expressing the tung oil from the meal. 6. Tests indicated that hulling the moist tung fruit in the grove does not interfere with the expression of the oil if the moist dehulled tung fruits are properly dried before pressing. 7. A process was developed for producing a clear tung oil by treating the crude oil with a chemical agent to precipitate certain non-oil constituents in the crude tung oil followed by either pressure filtration or centrifugation. 8. When tung oil filter cake was mixed with an equal amount of tung press cake, over 98 percent of the oil could be solvent-extracted by petroleum solvents. Presented at the American Oil Chemists’ Society meeting, New Orleans, La., May 10–12, 1944. Some of the material was presented at the American Tung Oil Association meeting. Pensacola, Fla., April 28–29, 1944, and published in the proceedings. Agricultural Chemical Research Division Contribution No. 145.     

The synthesis of sucrose esters from telomer monocarboxylic acids

Glycolipid biosurfactants possess excellent surfactant properties and can be useful model compounds for the synthesis of surfactants from materials available in large quantities. The incorporation of a long, branched alkyl group, which is a feature of glycolipids, into a synthetic surfactant was achieved by the transesterification of sucrose with the methyl ester of a selected telomer monocarboxylic acid mixture, in a solution reaction. Characterisation showed the product to be a mixture of mono- and diesters each comprising a different ratio of linear to branched alkyl chains in the substituted group. Surfactant properties of the mixture, and the chromatographically-separated components, when evaluated in both distilled water and a salt solution, were found to be superior to a range of sucrose stearates. In addition the biosurfactant analogues were found to be more effective than surfactants derived from β-keto alkyl esters of various sugars (including sucrose) but were not as efficient as these latter compounds.     

Polymerization of tung oil by reaction of phenols with tung oil

Investigation was made on the mechanism of polymerization in reactions of tung oil and phenols in the presence of an acid catalyst. It was made by means of comparative HLC and NMR analyses of the products of tung oil self-polymerization, other varied vegetable oil-various phenol reactions, and tung oil-various-in-functionality phenol reactions under given conditions. As a result, it was confirmed that polymerization in reactions of tung oil and phenols is attributed not to tung oil self-polymerization but to di- or trialkylation, with tung oil, of phenols, which can serve as crosslinking agents of tung oil.     

Renewable thermoset copolymers from tung oil and natural terpenes

The cationic copolymerization of tung oil, limonene, and myrcene as comonomers, initiated by boron trifluoride, is presented and discussed in this work. Dynamic mechanical analysis revealed that all copolymers behave as thermosets. FTIR spectra for both copolymers, after extraction with dichloromethane, suggested that the major component of the insoluble fraction was reacted tung oil (a cross‐linked triglyceride network). Likewise, unreacted tung oil was found to be the main component of the soluble phase. Also, all the copolymers showed only one tan δ peak, indicating no phase separation. Glass transition temperature (Tg) increased with the myrcene content and decreased almost linearly as the limonene content increased. Furthermore, the Fox and Loshaek model showed a relatively good prediction of the Tg values of the polymers. The Young's modulus ranged from 33.8 to 4.7 MPa for all tested thermosets. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41155.     

Preparation of pressure-sensitive adhesives from tung oil via Diels-Alder reaction

In this study, tung oil was polymerized with a dimaleimide (4,4’-methylene-bis(N-phenylmaleimide) (MPMI) and two diacrylates (poly(propylene glycol) diacrylate (PPGDA) and bisphenol A glycerolate diacrylate (BPAGDA) via Diels-Alder reaction (DA reaction) to prepare pressure-sensitive adhesives (PSAs). On the one hand, the polymer of tung oil and MPMI was readily prepared however it was too rigid to serve as a PSA. On the other hand, the polymerization of tung oil with PPGDA or BPAGDA resulted in PSAs with peel strengths ranging from 0.1 to 0.2 N cm⁻¹ and loop tacks ranging from 0.4 to 0.5 N. Nevertheless, tung oil reacted readily with acrylic acid to form adducts (TOAA) with lower content of conjugated diene groups than those of tung oil. The use of TOAAs instead of tung oil to polymerize PPGDA failed to increase the peel strength of the resulting PSAs. However, polymerizations of TOAAs with BPAGDA resulted in PSAs with much higher peel strengths and much higher loop tacks than the polymerization of tung oil with BPAGDA. In addition, the introduction of a small amount of MPMI in the polymerization of TOAA and PPGDA significantly shortened the curing time.