Robert T. O'Connor

Applications of Infrared Absorption Spectroscopy to Investigations of Cotton and Modified Cottons: Part I: Physical and Crystalline Modifications and Oxidation

The KBr technique to obtain spectra of cotton cellulose has been applied satisfactorily to an investigation of physical and crystalline modifications and to changes resulting from oxidation. Several experiments to illustrate applications are described. The potential applications to investigations suggested in the literature are reviewed. It has been shown that infrared absorption spectra of cotton cellulose can be used to follow changes in hydrogen bonding by the classical method of observing the exact wavelengths of the O-H stretching vibrations. Degree of crystallinity can be measured quantitatively by use of ratios of intensities of preselected absorption bands. Oxidation changes can be followed only where such processes result in the formation of C = O groups per se in the oxidized cotton.

Modification of vegetable oils. XI. The formation of trans isomers during the hydrogenation of methyl oleate and triolein

Summary1. During the hydrogenation of methyl oleate, trans isomers are formed at a very rapid rate. As much as 38% of trans isomers formed while the first 10% of methyl stearte was formed.2. The rate of formation of trans isomers in methyl oleate undergoing hydrogenation is increased by increasing the temperature, increasing the catalyst concentration, and decreasing the degree of dispersion of the hydrogen.3. The hydrogenation of methyl oleate always resulted in the establishment of an equilibrium between cis and trans isomers, and irrespective of the conditions employed the concentration of trans isomers was always 67%, calculated on the basis of total unsaturated constituents.4. It is concluded that all of the iso-oleic acids formed during the hydrogenation of methyl oleate adsorb hydrogen at the same rate as oleic acid and are adsorbed and desorbed from the nickel catalyst with equal ease.5. Trans isomers are formed at a slightly lower rate during the hydrogenation of triolein than in the case of methyl oleate.6. Partial hydrogenation of triolein also results in the establishment of an equilibrium between cis and trans isomers of oleic acid but at values of less than 67% of trans constituents (based on the total unsaturated constituents) observed with methyl oleate. The equilibrium concentration was found to vary with the conditions of hydrogenation and was found to be 62% at 200°C. and 57% at 175°C.

The infrared spectra of mono-, di-, and triglycerides

SummaryThe infrared spectra from 2 to 12 microns of chloroform ( solutions of several glycerides have been measured and studied with a view to possible analytical applications. These spectra are presented, and conclusions which can be obtained from their examination are reported in this paper.The principal bands, common to the spectra of all glycerides, have been tabulated with correlations of the vibrating groups which give rise to them. The analytical significance of the infrared spectra is considered in detail for three specific regions: a) the O−H stretching vibration region, about 3.0 microus; b) the C−O stretching vibration region, about 9.0 microns; and c) the 10.0-micron region of C−H bending, about the C=C group.Analyses of these regions of the spectra indicate that infrared absorption can be used to detect and to determine mono-, di, and triglycerides in admixtures and that the method for the determination of transisomers can, with modifications, be extended to include analysis of triglycerides.

Processing of cottonseed

Summary1.The pigmentation of cooked cottonseed has been shown to depend principally upon the moisture content and period of heating of the seed.2.Several samples of crude hydraulic-pressed and screw-pressed oils produced under known processing conditions were found to differ markedly from each other with respect to their original colors and refining characteristics.3.The screw-pressed crude oils were more deeply colored and contained one principal pigment, whereas the hydraulic-pressed oils contained two principal pigments.4.The absence of significant amounts of gossypol in the crude oils has been demonstrated by means of a new technic for the quantitative isolation of gossypol.5.The crude oil pigments differed from gossypol, but like gossypol, they were removed during alkali refining.6.The pigmentation of the crude oils has been shown to depend principally upon the pigmentation of the original seed and the moisture content of the seed during cooking.7.On the basis of their absorption spectra it has been deduced that the alkali-refined hydraulic-pressed oils contain two to three pigments originally present in the crude oils whereas the alkali-refined serewpressed oils contain these same pigments as well as a large number of decomposition products of the principal crude oil pigment.

A simplified method for the preparation of α- and β-eleostearic acids and a revised spectrophotometric procedure for their determination

SummarySimplified methods for the preparation of pure α- and β-eleostearic acids are described. These procedures involve saponification of α- and β-tung oils under mild conditions, followed by direct crystallization of the liberated acids at −20°C. from ethanolic solution. Only one recrystallization from ethanolic solution at +5°C. was required to produce the pure acids.Absorptivities obtained from measurements of the ultraviolet absorption revealed α-eleostearic acids of from 3–4% higher purity than those used in obtaining the equations previously recommended for the simultaneous determination of α- and β-eleostearic acids. This has necessitated a revision of these equations. Equations for the determination of each isomer from both cyclohexane and ethanol are reported. Equations are also given for an independent determination of total eleostearic acid, and for the determination of one isomer in the absence of the other.Infrared absorption spectra in the rock salt region from 2–15 microns have been measured from potassium bromide discs. These solid-state or crystalline spectra reveal, in addition to the prominent bands assigned to characteristic groupings of the eleostearic acid molecule, the progression bands by means of which carbon chain length can be computed.

Applications of Infrared Absorption Spectroscopy to Investigations of Cotton and Modified Cottons Part II: Chemical Modifications

The potassium bromide disc technique is being used for rapid, simple, and reproducible measurement of the infrared spectra, of modified cotton fibers, yarns, and fabrics. Ap plications of the procedure have demonstrated that chemical modification can be readily detected and identified and that the extent of treatment can be quantitatively estimated. Experiments have been designed to select bands most useful in investigations of cotton modified by esterification. etherification, or replacement reactions. The examples cited illustrate the potential usefulness of infrared absorption spectra to studies in this field. A list has been prepared of 50 infrared absorption bands (and correlations with vibrating groups which give rise to them) which summarize the spectral characteristics which have been found most useful in investigations of cottons modified by esterification, etherifica tion, and replacement reactions.

The infrared spectra and the structural relationships between alpha- and beta-eleostearic acids and their maleic anhydride adducts

SummaryThe cis, trans, and positional configuration of alpha-and beta-eleostearic acids have been investigated. The maleic anhydride adducts of alpha-and beta-eleostearic acids were prepared and subjected to hydrogenation, selective epoxidation, and esterification. Two epoxy derivatives of the maleinated beta-eleostearic acid were isolated and characterized. Infrared spectra of these maleic anhydride adducts and their various derivatives have been measured in the rock salt region, 2–12 microns. These infrared data together with chemical evidence have been used to confirm the structure of alpha-eleostearic acid as 9-cis, 11-trans, 13-trans octadecatrienoic acid and beta-eleostearic acid as 9-trans, 11-trans, 13-trans octadecatrienoic acid.Complete infrared spectra are presented for authentic samples of alpha-and beta-tung oil, China wood oil, oiticica oil, and alpha-and beta-eleostearic acids. Infrared absorption curves are presented, including the maleic anhydride adducts of alpha-and beta-eleostearic acids, various derivatives of these adducts and the following reference compouds: maleic anhydride, dimethyl maleate, dimethyl fumarate, the butadiene-maleic anhydride adduct and its dimethyl ester.

X-Ray Fluorescence Analysis of Modified Cottons

The application of x-ray emission techniques to the qualitative and quantitative elemental analysis of chemically and additively modified cotton textiles has been investi gated. Sample preparation and calibration techniques which appear to be suitable for the analysis of textile materials have been devised. The method has been applied to a variety of samples containing some 20 individual elements. The technique is useful for identifying the elements present in fabrics finished with poorly defined agents. It has been applicable to problems involving the add-on and subsequent loss of fungicidal agents containing such elements as Cd, Zn, Se, Cl, S, and P. Typical results obtained with a number of modified cottons are given.

Ricinelaidic acid and methyl ricinelaidate. Their preparation and determination by infrared spectroscopy

SummaryImproved methods for the preparation of ricinelaidic acid and methyl ricinelaidate are described. The methods depend upon the elaidinization of methyl ricinoleate with a relatively small quantity of a nitrite-nitric acid solution, fractional crystallization of the methyl ricinelaidate, and its subsequent hydrolysis to ricinelaidic acid. The infrared spectra of these two compounds are presented, and bands arising from a deformation of the C−H about thetrans C=C group are discussed. Absorptivity values for this band in chlorform and in carbon disulfide solutions are given as additional criteria of purity of ricinelaidic acid and its methyl ester. The infrared absorption procedure for the quantitative determination of isolatedtrans ethylenic bond was applied to the determination of both ricinelaidic acid and methyl ricinelaidate. Details of specific procedures for the determination of each compound are given with the equations necessary for their calculation. Use of these methods is illustrated with the analysis of elaidinization mixtures. The repeatability and accuracy obtaineble are given. A value is reported for the methyl ricinoleate—methyl ricinelaidate equilibrium and the mechanism of the reaction is discussed briefly.

Storage of cottonseed and peanuts under conditions which minimize spectrophotometric changes in the extracted oil

Summary1.Cottonseed was stored for over a year without appreciable change in red gossypol content by adjusting the moisture content to 8% or less and placing in closed containers at 1° or at −18°C. Cottonseed stored at room temperature, 27°C., showed a large increase in red gossypol content.2.Cottonseed stored in the above manner at 1° or at −18°C. showed little or no increase in the non-gossypol absorption of the extracted oil at 236 mμ, the region of diene conjugation. This property of the extracted oil showed a large increase when cottonseed was stored at room temperature, 27°C.3.Gossypol dissolved in cyclohexane has spectrophotometric extinction coefficients (concentration in g. per liter, solution depth 1 cm.) of 207, 70, and 40 at the maxima at 236 mμ, 286 mμ, and 358 mμ, respectively.4.The extracted oil from peanuts stored for over four years at room temperature, 27°C., showed a much greater absorption in the region of 227 mμ to 234 mμ than did peanuts stored for the same time at 1° or at −18°C.