Long-chain Compounds Research Articles

Origin of long-chain alkylcyclohexanes and alkylbenzenes in a coal-bed wax

A coal-bed wax was fractionated and analyzed using capillary column GC and combined GC/MS. It was found that the major components in the wax were n-alkanes (55.6%), cyclic/branched alkanes (26.0%), and several homologous series of alkylbenzenes (5.7%). All alkylbenzene isomers (except 6- n-alkyl- m-xylene) were positively identified by comparison with the retention times and mass spectra of newly synthesized authentic standards. 5- n-Alkyl- m-xylene, 2- n-alkyl- p-xylene, 4- n-alkyl- m-xylene, 4- n-alkyl- o-xylene, 2- n-alkyl- m-xylene, and 3- n-alkyl- o-xylene were identified for the first time from geological sources. All of these long-chain alkyl compounds (e.g., n-alkylcyclohexanes, n-alkylbenzenes, n-alkyl- o-toluenes, n-alkyl- p-toluenes, and 5- n-alkyl- m-xylenes) have similar total carbon number distributions and maxima with a slight even over odd carbon number preference between C 28–C 30. Moreover, the carbon number distributions of these compounds resembled those of the n-alkanes found in the same wax with slight odd over even carbon preference between C 27–C 21. This indicates that the alkylcyclohexanes and alkylbenzenes may have the same fatty acid precursors as the n-alkanes. The alkylcyclohexanes and alkylbenzenes could have been formed by direct cyclization and aromatization, while the n-alkanes could have been formed by decarboxylation of the straight chain fatty acids. This explanation is further supported by the identification of homologous series of tetramethyl- n-alkylbenzenes and pentamethyl- n-alkylbenzenes with relatively high abundances at C 15, C 16, and C 18, and a fatty acid distribution with maxima at C 16 and C 18. Based on these findings, mechanisms for the conversion of fatty acids or alcohols to alkylcyclohexanes and alkylbenzenes are proposed.

Determination of quaternary ammonium compounds by capillary electrophoresis using direct and indirect UV detection

The determination of alkyl and alkylbenzyl quaternary ammonium compounds can be difficult owing to the polarity of the compounds, the formation of micelles by longer chain compounds and the lack of a chromophoric substituent for detection by standard separation techniques. The development of a free zone capillary electrophoresis method necessitated the use of organic modifiers in order to disrupt the formation of micelles by the longer chain (C 12) surfactants. The selectivity obtained by using various levels of tetrahydrofuran as an organic modifier allowed the separation of a mixture of alkylbenzyl and alkylethylbenzyl quaternary compounds. The separation of alkyltrimethyl and dialkyldimethylammonium compounds was accomplished by the addition of a chromophoric cationic compound to the buffer system in order to allow the detection of the compounds with a standard UV absorbance detector. By varying the electrophoretic mobility of the indirect detection reagent, a variety of alkyl quaternary compounds, ranging from tetra- methylammonium chloride to stearyltrimethylammonium chloride, can be detected with good peak shapes. The use of these methods for the determination of quaternary ammonium compounds will also be discussed. The use of internal standard methods and the linearity and linear range of the technique are considered.

Long-chain compounds from Leucas aspera

Two new long-chain compounds, 1-hydroxytetratriacontan-4-one and 32-methyltetratriacontan-8-ol, along with dotriacontanol have been isolated from shoots of Leucas aspera and characterized by spectral data and chemical studies.

Effects of long-chain aliphatic compounds on the germination and initial growth of corn, radish and spinach seedlings, and on hydrological properties of a sand growth medium

A greenhouse and laboratory study was carried out to determine the effects of various amounts (0.5–2.0%) of long-chain aliphatic compounds (LCA) of beeswax on the germination and initial growth (25 d) of corn, radish and spinach seedlings, and on the hydraulic properties of the sand growth medium. Complete emergence was obtained for corn, irrespective of aliphatic addition, whereas, the germination rate of the other two species decreased gradually as the amount of aliphatics added increased. With 2% LCA, 40 and 60%, respectively, of radish and spinach seeds failed to germinate. Dry matter yields of the three crops were reduced by the incorporation of aliphatics. The inhibitory effect of LCA on radish and spinach seedlings, coupled with a reduced plant density, resulted in a more dramatic yield reduction. Although there was a slight increase in the total porosity of the sand treated with LCA, the addition of LCA markedly decreased amounts of pores in the 25- to 100-μm class. It was concluded that the LCA influenced seed germination to various degrees, depending on the plant species, and that these compounds had a definite inhibitory effect on growth of seedlings, mainly through changes in the hydraulic properties of the sand. Key words: Long-chain aliphatics, germination, hydraulic properties

Improved and simplified tissue extraction method for quantitating long-chain acyl-coenzyme A thioesters with picomolar detection using high-performance liquid chromatography

A method has been developed that permits rapid and easy tissue extraction of long-chain acyl-coenzyme A (acyl-CoA) thioesters with sensitive quantitation by reversed-phase high-performance liquid chromatography (RP-HPLC). Tissue homogenants are extracted using a reserve Bligh—Dyer technique, and long chain acyl-CoA esters are harvested in the methanolic aqueous phase. Complex lipids and phospholipids are removed in the chloroform-rich organic Bligh—Dyer second phase, and long-chain acyl-CoA compounds are further purified from the methanolic aqueous Bligh—Dyer first phase on C 18 extraction columns after removal of the methanol. The eluted and purified acyl-CoA esters are then quantitated by RP-HPLC using heptadecanoyl-CoA as an internal standard resulting in a detector sensitivity of about 12 pmol. Ten long-chain acyl-CoA esters from C 12:0 to C 20:4 were identified and separated from canine renal cortex and murine liver samples. The predominant acyl-CoA peaks from both kidney and liver were 14:0, 16:1, 16:0, 18:1, 18:2 and 20:4. Murine liver also produced 18:0 and all peaks disappeared after alkaline hydrolysis of the samples. This extraction and quantitation technique can successfully be used for tissue samples as small as 20 mg, and many samples can be processed in a short period of time. The simplicity of the extraction procedure and the sensitivity of the assay make this an attractive alternative approach to quantitating long-chain acyl-CoA thioesters from complex biological samples such as tissues.

The secretion of the ventral glands in Nematus sawfly larvae

Nematine larvae possess ventral glands which contain compounds that protect the larvae from predation. More than 50 volatile compounds have been identified in secretions from the glands of 13 Nematus species. Monoterpenes constitute the major part of the secretion of five species in which long-chain aliphatic compounds (LCAC; C 15–29) are also detected. In four other species, short-chain aliphatic compounds (SCAC; C 6–8) and aromatic compounds are predominant, LCAC are also present, but monoterpenes are absent. In the four remaining species, the secretion is composed basically of LCAC. The diversity of chemotypes within the genus is discussed.

Improved inhibitors of glucosylceramide synthase.

An inhibitor of glucosylceramide (GlcCer) synthase, 1-phenyl-2-decanoylamino-3-morpholino-1-propanol (PDMP), has been reported to deplete cells and mice of their glucosphingolipids. This inhibitor has proved useful for the elucidation of the many functions of this lipid family [reviewed by Radin, N.S. & Inokuchi, J. (1991) Trends Glycosci. Glycotechnol. 3, 200-213]. In the present study, we have synthesized homologs of PDMP having different acyl chains (C6-C18) and compared their effectiveness for the inhibition of GlcCer synthase in vitro and their inhibition of GlcCer, protein, and DNA synthesis in cultured MDCK (Madin-Darby canine kidney) cells. Using MDCK homogenates and mouse brain and liver microsomes, we found that the C6 compound was relatively inactive and that the longer chain compounds did not differ much in inhibitory power. However, the use of intact MDCK cells showed that the longer chain homologs were much more effective in inhibiting GlcCer synthesis, cell growth, and incorporation of [3H]thymidine. Tests with two radioactive homologs showed that the inhibitor with a longer acyl chain was taken up much more effectively by MDCK cells and that this difference explains the much greater effectiveness of this homolog in intact cells. The inhibitors were effective when solubilized either with a nonionic detergent or with bovine serum albumin. The extent of decrease in DNA synthesis was not directly proportional to the decrease in cellular glucosylceramide, possibly because only a low level of the glycolipid is needed for DNA synthesis.

Volatiles from interactions of Maillard reactions and lipids

This article provides current information on the production of volatile compounds from interactions of Maillard reactions and lipids. It includes a brief introduction outlining the Maillard reactions, the Strecker degradation of amino acids, and the oxidation of lipids. It highlights those compounds derived from these reactions that could interact to form volatile flavor components during the processing or cooking of food. The article discusses results obtained from model systems involving interactions between (1) Maillard reaction products and carbonyl compounds, (2) amino acids and carbonyl compounds, (3) amino acids and derivatives of fatty acids, and (4) Maillard reaction products, triglycerides and phospholipids. The qualitative and quantitative effects that triglycerides and phospholipids have on the formation of volatile Maillard products are also discussed. Particular attention is given to those long-chain alkyl heterocyclic compounds formed during these reactions, proposed methods for their formation, and their aromas. The role that such compounds play in food flavors is discussed with reference to those volatile compounds identified in certain cooked foods, such as meat (beef, lamb, and pork), chicken, potatoes (baked, French-fried, and crisps), and beverages (coffee, tea, and cocoa).

Study on Low-Frequency Raman Spectra of n-Decylammonium Chloride

The low-frequency Raman spectrum of n-decylammonium chloride was measured as a function of temperature in the temperature range from 290 to 340K, and the longitudinal acoustical mode vibration band was assigned. The results showed that there are two phase transitions at 313K and 321K, respectively. The phase transition at 313K is mainly induced by change of hydrocarbon chain conformations, while that at 321K is mainly induced by change of order degree of molecular packing. The results suggest low-frequency Raman spectroscopy is a useful probe of structural phase transition for long-chain compounds.

Tobacco Leaf Protein: I. An Evaluation of the Use of Putative Chemical Growth Enhancers for Tobacco Leaf Protein Production

Abstract Effects of foliar applications of long-chain fatty compounds on production of leaf protein from tobacco genotypes were evaluated. Triacontanol, purported to be a growth stimulant, had minimal effects on most experimental parameters. A propriety product, AgroLizer™, appeared to exert greater influence but results were inconclusive. Chemical treatments interacted with environmental conditions and tobacco genotype. Acid precipitation of the green fraction resulted in a pellet that could be easily removed by low speed centrifugation but produced a white fraction with lower protein percentage than heat precipitation of the green fraction. Triacontanol delayed flowering and extended vegetative growth in some genotypes. Increased cured leaf yields of flue-cured and Maryland type tobaccos were consistent but not statistically significant. An important finding was discovery of a genotype, T.I. 401, that produced high amounts of extractable leaf protein regardless of growth stage. This variety became the object of a follow-up investigation.

Influence of gas on the properties of monomolecular films of long-chain organic compounds spread at gas—mercury interfaces

The influence of gas on surface pressure-area per molecule ( π-A) and film thickness-area per molecule ( d-A) curves of the monolayers of arachidic acid (AA), octadecyltrichlorosilane (ODTCS), and n-octadecane( n-OD) were studied at helium/mercury ( HeHg) and oxygen/mercury ( O 2Hg ) interfaces. The curves for AA and ODTCS were found to be different at the HeHg and O 2Hg interfaces, but for n-OD, the curves were identical at the two interfaces. Monolayer properties of AA at O 2Hg interface were attributable to hydrogen bonding of head groups to an oxide film partially formed on mercury surfaces and resulted in tilted orientation of hydrocarbon chains. In the case of ODTCS at O 2Hg interface probable surface chemical reaction resulted in the formation of macroscopic patches on Hg surface, whereas molecular properties of AA and ODTCS at the HeHg interface and of n-OD at both interfaces resulted from molecular orientation lying flat on mercury surface in the absence of the hydrogen bonding.

Surface effects on phase transition behaviour and thermal polymerisation of long-chain compounds in micro DSC measurements

The surface effects of the aluminium sample pan on the melting behaviour of stearic acid and also on the phase transition behaviour and thermal polymerisation of N-octadecyI acrylamide during differential scanning calorimetry (DSC) were investigated. The surface effects in the micro DSC measurements can be classified into two types. In the case of stearic acid, when the weight of sample was smaller than 0.01 mg, the molar heat of fusion estimated from the peak area in the first heating curves increased abruptly up to two or three times the normal value (64.3 kJ mol −1); however, in the second heating curves obtained with samples stored for a long time after the first heating at room temperature, the molar heat of fusion tends to decrease. In contrast, in the DSC curves for N-octadecyl acrylamide with sample weights of around a milligram, an endothermic peak for melting appeared at 75°C, followed by a broad exothermic peak for thermal polymerisation ranging from 115 to 155°C; when the sample weight is smaller than a critical value of around 0.2 mg, the thermal polymerisation and also the polymorphic transition are suppressed strongly. The surface effects are attributed to the strong interaction, such as chemisorption, of the polar head group with the surface of the pan which restricts the conformational freedom of the functional groups.

Organo-bentonites with quaternary alkylammonium ions

AbstractThree bentonites, from Bavaria, Wyoming and Brazil, were separated into various fractions. The layer charge was determined by alkylammonium ion exchange and increases with particle size from 0·25 Eq/(Si, Al)4O10 (<0·06 µm) to 0·28 Eq/(Si, Al)4O10 (1–10 µm). The charge density corresponds to an interlayer cation density of 0·75–0·80 mEq/g silicate. Total amounts of 0·90–1·0 mEq of different surfactant cations (dimethyl dioctadecylammonium, trimethyl tetradecylammonium, alkylammonium ions) are bound per gram silicate. The difference between the total and the interlayer amount of surfactant ions decreases with increasing particle size. The amounts exceeding the interlayer CEC are bound at the edges. Tetramethylammonium (TM) ions restrict the interlayer adsorption of long-chain quaternary alkylammonium ions such as trimethyl tetradecylammonium (TMTD) ions, and only monolayers of flat-lying surfactants are formed. A ratio of TMTD and TM is attained which leads to densely packed monolayers of organic ions. The collapsing effect is smaller for tetraethylammonium ions so that considerable amounts of TMTD ions are adsorbed in bilayers. When bentonites are reacted with quaternary alkylammonium ions of technical quality some selectivity is observed according to particle size and layer charge. Smaller particles with lower charge density preferentially bind the longer chain compounds, whereas large particles with higher charge density select smaller sized surfactants.

Stereoisomere Aromastoffe

5-Alkyl-substituierteδ-Lactone finden sich als aromarelevante Substanzen in tierischen Fetten, aber auch in einigen Früchten. Vor kurzem gelang die erste direkte gaschromatographische Stereodifferenzierung einigerδ-Lactone an der chiralen Phase Oktakis(3-O-butyryl-2,6-di-O-pentyl)-γ-cyclodextrin [4]. Es wird nun die Enantiomerentrennung derδ-Lactone bis zu den langkettigen Verbindungenδ-Trideca-(δ-C13-)- undδ-Tetradeca-(δ-C14-)-lacton aufgezeigt. Über optisch reine Referenzsubstanzen konnte die Elutionsfolge S(I), R(II) der drei wichtigsten aromarelevanten Vertreter dieserδ-Lactonklasse bestimmt werden. Die Enantiomerenverteilung der C8-, C10-, C12-δ-Lactone im Wasserdampfdestillat verschiedener Milchprodukte (Milch, Sahne, Butter), in Margarine sowie im Kokosnußfleisch wurde exemplarisch mit Hilfe der HRGC, auch unter Einsatz der multidimensionalen Gaschromatographie (MDGC), untersucht. Es zeigten sich charakteristische, substratspezifische Enantiomerenverteilungen. Die Verteilungsmuster der untersuchten Spiegelbildisomeren aus Kokosnüssen unterschieden sich wesentlich von denen der Milchprodukte.

Polypeptide spheres. VII. Macroreticulation of spherical poly(γ‐methyl‐L‐glutamate) beads

AbstractSpherical beads from poly(γ‐methyl‐L‐glutamatate) alone were prepared using various diluents for macroreticulating by the “suspension and evaporation” method. The porosity and the pore size of the beads obtained were remarkably dependent on the chemical structure of a diluent. This is related to the specific miscibility of a diluent with poly(γ‐methyl‐L‐glutamate). For example, decahydronaphthalene made the beads much more macroporous than tetrahydronaphthalene with similar hydrophobisity: the aromaticity of diluent increases the miscibility. However, it was found that long‐chain alkyl compounds with a miscible group such as methyl dodecanoate, oleic acid, linoleic acid, and dialkyl‐phthalate were not only very effective for macroreticulating, but also induced narrow pore‐size distribution. In addition, the diluent influenced physicochemical properties of the beads to cause specific affinity to proteins.

Enantiomerically Pure Insect Pheromones: The Carbohydrate Synthetic Approach

1. Introduction During the past two decades, there has been a rapidly growing interest in the field of intra- and interspecific chemical communication. Insect pheromones in particular have been intensely studied with respect to their potential use as a component of integrated pest management.1 Structural identification and chemical synthesis of these so-called “semiochemicals” have developed in harmony with the biological research evaluating structure-activity relationships. Most of the pheromones identified, studied, and synthesized come from the order Lepidoptera: very often these pheromones consist of long-chain olefinic compounds in which regio- and cis/trans-isomerism determine their biological activity. Several well documented reviews have appeared, emphasizing both coupling of alkyl halides or similar electrophilic substrates with metallo-organic reagents (“Wurtz-chemistry”) and carbonyl olefination, such as the Wittig reaction and its huge variety of modifications for regio- and stereoselective C-C bond formation. 2-8 The importance of chirality in pheromone perception by insects has been recognized and the role of optical isomerism and diastereoisomerism in behavioral discrimination has been firmly established through the combination of synthesis and bioassay. Some reviews bring good insight into the diverse strategies employed in synthesizing chiral pheromones, 8,9 originating principally from the orders Coleoptera and Hymenoptera. In spite of the increasing efficiency of asymmetric synthesis in the semiochemical field 10 , only few methods afford highly optically pure compounds with known absolute configuration. On the other hand, optical resolution is not always satisfactory and the absolute configuration of the resolved material has to be determined by some means. 11 Enantiospecific synthesis starting from naturally occuring chiral molecules such as amino or hydroxy acids, terpenes and sugars appears to be the safest path leading to highly optically pure pheromones. The prominent role of readily available carbohydrate starting materials within this “chiral synthon approach” has been clearly demonstrated. 12 The present review offers a 1976 to 1990 literature survey of the use of hexoses (mainly D-glucose and derivatives) and pentoses for the enantiospecific synthesis of chiral pheromones, issuing principally from the order Coleoptera. 13

Surfactant monolayers on a clean mercury surface: Apparatus and experiments

A Langmuir trough for studying monolayers on a mercury surface was constructed usingT. Smith's design. The surfactant (long-chain alkyl-trimethylammonium compounds) in aqueous solution were spread on a clean mercury surface in an atmosphere of helium, and the surface pressure re-areaA and thickness of surface filmd-areaA curves were obtained. Theπ-A curves were characterized by the appearance of multiple inflection points and plateaus, being explained as stepwise dense surface packing of molecules, and the formation of multilayers by film compression with long axes of molecules lying flat on the mercury surface.

Anion-exchange reactions of layered double hydroxides

Layered double hydroxides are antitypes of 2/1 clay minerals. In spite of a high surface charge density, as in micas, they react easily with various types of organic anions. Short- and long-chain anions are rapidly exchanged for the inorganic interlayer anions, and high degrees of reaction are attained. The pronounced preference of primary long-chain compounds as typical of the more highly charged clay minerals is not observed. The small equivalent area forces the alkyl chain compounds (fatty acid anions, dicarboxylates, alkyl sulfates) to point away from the interlamellar surfaces and to form monomolecular films of high regularity

Infrared spectra of tetrakis (alkylthio) tetrathiafulvalenes

Infrared spectra were measured for tetrakis (alkylthio) tetrathiafulvalenes (abbreviated TTC n-TTFs ( n=1−18)) as powder samples and single crystals. In the compounds with n = 1−26, the stretching vibrational bands of the CH 2 and CH 3 groups and their relative intensities vary with n. The compounds with n ⪆ 7−9 show nearly identical spectra, where the stretching deformation vibrations of the CH 2 groups develop and approach those in polyethylene. This observation suggests that the high electrical conduction by the molecular fastener effect in the long-chain compounds of TTC n-TTFs correlates significantly with the development of polyethylene-like alkyl chains in the crystal.

Raman Spectra and Annealing Processes in Glassy Films of Long-Chain Organic Compounds

Abstract Glassy films of long-chain organic compounds were made by the evaporation onto cold metal surfaces. Raman spectra of these films are compared with those of crystal and liquid states. Annealing processes in these films were found to involve some molecular conformational changes which occur successively in several temperature regions. The results on hexatriacontane are shown as an example.