Alkenoic Acids Research Articles

Biochemistry of Human Axilla Malodor and Chemistry of Deodorant Ingredients

Key human axilla malodorants are hexenoic acid (3) and 3-hydroxy-3-methyl-hexanoic acid (5), accompanied by some 25 structurally related hydroxyalkanoic acids and alkenoic acids. These sweat acids are secreted in the axilla in the form of odorless glutamine conjugates and are released upon enzymolysis by AMRE (Axillary Malodor Releasing Enzyme), produced by Corynebacteria. The sulfanylalkanols 8–11 represent another important group of axilla malodor compounds that are also secreted in the form of odorless precursors. The major precursors are cysteine–glycine sulfanylalkanol conjugates of type 14 and the minor precursors are cysteine sulfanylalkanol conjugates like 15. The release occurs upon action of a ?-lyase of axilla bacteria. Besides the classical approaches of axilla malodor masking using fragrances, the use of chemicals to neutralize malodorants is described. The elucidation of the biochemistry of the sweat acid release has allowed the development of fragrance precursors that act as competitive substrates to the natural malodor precursors as well as the development of specific antagonists that block AMRE. Finally, the characterization and functional expression of a first human malodor receptor presents an interesting approach for future development of axilla malodor blockers.

Laboratory measurements of the oxidation kinetics of organic aerosol mixtures using a relative rate constants approach

Organic aerosols in the atmosphere are exposed to oxidants, but the oxidation kinetics are largely unknown. We investigate the decay of organic species in laboratory‐generated organic aerosols exposed to atmospherically relevant ozone concentrations in a smog chamber. The experiments were conducted using five different organic aerosols, varying in complexity from three to twelve components. These mixtures include alkenoic acids, alkanoic acids, alkanedioic acids, n‐alkanes, and sterols and are designed to simulate meat cooking emissions. A relative rate constants approach was used to compare reaction rates of individual organic species and to compare the reaction rates of the aerosol species to gas phase tracers. Significant decay was observed for all species (except for the n‐alkanes) in at least one of the experimental systems. By relating the decomposition of condensed phase alkenoic acids to gas phase alkenes, we show that the reaction rate constants of oleic acid and palmitoleic acid evolve as the aerosol is processed, decreasing by a factor of ∼10 over the course of a 4‐hour experiment. The decay rate constants of cholesterol, oleic acid, and palmitic acid all depend strongly on aerosol composition, with more than an order of magnitude change in the effective rate constants depending on mixture composition. Effects of aerosol composition are likely to be even more significant in atmospheric aerosol, where particle compositions are highly variable. The data presented here indicate these mixture effects are complicated, making it difficult to extrapolate from simple laboratory systems to atmospherically relevant conditions.

Volatiles in the Dorsal Abdominal Glands and Exuviae of <I>Leptocoris abdominalis</I> and <I>Leptocoris augur</I> (Heteroptera: Rhopalidae)

Compounds in the dorsal abdominal glands (DAGs) of adults and nymphs, and exuviae of two scentless plant bugs Leptocoris abdominalis (F.) and Leptocoris augur (F.) (Heteroptera: Rhopalidae), were studied by gas chromatography-mass spectrometry. For both species, two dorsal abdominal glands (median and posterior glands) are found in the nymphs, whereas in adults only the posterior gland is functional and the median gland is reduced. Monoterpenes are the major compounds in posterior glands for both species. For L. abdominalis β-pinene is most abundant monoterpene and for L. augur, limonene is most abundant monoterpene. Alkenals and alkenoic acids were found in median glands of both species. There was no sexual dimorphism in the morphology and the contents of the DAGs of adults. Analysis of the compounds found in the exuvia indicated that components in the median gland were shed with the exuvia. Quantitative analysis of the major monoterpenes and alkenals in the DAGs of different ages of L. abdominalis supported the observation that components in the posterior gland were retained in the insect after each molting. Possible functions of the components in the DAGs are discussed.

Simple Amidation of Unprotected Phenol‐Containing 2‐Alkenoic Acids.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Photochemical oxidation and changes in molecular composition of organic aerosol in the regional context

This paper presents evidence that condensed‐phase organic compounds are significantly oxidized in regional air masses and in locations affected by regional transport, especially during the summer. The core of the paper examines a large data set of ambient organic aerosol concentrations for removal of reactive compounds relative to less‐reactive compounds. The approach allows visualization of both photochemistry and mixing of emissions from multiple sources in order to differentiate between the two phenomena. The focus is on hopanes and alkenoic acids, important markers for motor vehicle and cooking emissions. Ambient data from Pittsburgh, PA and the Southeastern United States contain evidence for significant photochemical oxidation of these compounds in the summertime. There is a strong seasonal pattern in the ratio of different hopanes to elemental carbon consistent with oxidation. In addition, measurements at rural sites indicate that hopanes are severely depleted in the regional air mass during the summer. Alkenoic acids also appear to be photochemically oxidized during the summertime; however, the oxidation rate appears to be much slower than that inferred from laboratory experiments. The significance of photochemistry is supported by rudimentary calculations which indicate substantial oxidation by OH radicals and ozone on a time scale of a few days or so, comparable to time scales for regional transport. Oxidation is non‐linear; therefore it represents a very substantial complication to linear source apportionment techniques such as the Chemical Mass Balance model.

Simple amidation of unprotected phenol-containing 2-alkenoic acids

A series of amides of 2-E-alkenoic acids have been synthesised through the activation of these acids with dicyclohexylcarbodiimide / pentafluorophenol and further reaction with amines under microwave irradiation. In daylight, the E-configured amides undergo a slow photochemical E/Z-isomerisation. Photoirradiation experiments with selected 3-(hydroxyphenyl)-2(E)-alkenamides were carried out using a high pressure mercury UV lamp.

Iron(II)‐Catalyzed Chlorolactamization of γ,δ‐Unsaturated Carboxylic Acids.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Polar organic compounds measured in fine particulate matter during TexAQS 2000

Fine particle samples were collected at three sites in the Houston area during TexAQS 2000. Polar organic species including levoglucosan, n -alkanoic acids, n -alkenoic acids and dicarboxylic acids were quantified to characterize the composition of local ambient organic aerosols. Levoglucosan, a tracer for biomass burning, was measured as a dominant compound, followed by n -alkanoic acids. The compound distribution of higher molecular weight n -alkanoic acids (⩾C 22 ) was consistent with biogenic emission sources. n -Alkenoic acids exhibit variable concentrations during sampling period with high ratios of octadecanoic to octadecenoic acid. The concentrations of dicarboxylic acids are compared with unapportioned organic carbon calculated by the chemical mass balancing technique. This correlation supports the conclusion that diacids are generated by photochemical reactions and contribute to the unapportioned organic mass. Data collected during a regional wood smoke episode are used to examine the influence of wood combustion to ambient particulate matter concentrations.

Alkenone and alkenoic acid compositions of the membrane fractions of Emiliania huxleyi

The lipid classes and unsaturation ratios of long-chain alkenones ( nC 37–C 39), related alkyl alkenoate compounds ( nC 37–C 38) and alkenoic acids ( nC 14–C 22) were determined in isolated membrane and organelle fractions of Emiliania huxleyi. The percentage distribution of these compounds was predominantly high in the endoplasmic reticulum (ER) and coccolith-producing compartment (CPC)-rich membrane fraction, although alkenones and alkenoates could be detected in all membrane fractions. In particular, the alkenones were mainly located in CPC, since their distribution was closely correlated with that of uronic acids which are markers of CPC. In contrast, the alkenoic acids seemed to be mainly located in chloroplast (thylakoid)-rich fractions. The alkenone unsaturation ratio and the ratio of alkenoates to alkenones were similar in all fractions, while the unsaturation ratio of alkenoic acids in the thylakoid-rich and plasma membrane (PM)/Golgi body-rich fractions was overwhelmingly higher than that in the ER/CPC-rich fractions. Thus, alkenoic acids seemed to be typical membrane-bound lipids, and could be closely related to photosynthesis and involved in regulating membrane fluidity and rigidity in E. huxleyi. It is presumed from these results that the alkenones and alkenoates were membrane-unbound lipids that might be associated with the function of CPC.

Induction of histone acetylation and inhibition of growth by phenyl alkanoic acids and structurally related molecules.

A structure-activity study was undertaken to determine the influence of side chain length of phenyl alkanoic acids and the degree of unsaturation of phenyl alkenoic acids on the induction of histone acetylation and inhibition of cancer cell proliferation. Studies on cell proliferation were performed with DS19 mouse erythroleukemic cells, PC-3 human prostate cancer cells and Caco-2 human colon cancer cells. Actions on histone deacetylase and the induction of histone acetylation were compared for 4-phenylbutyrate and structurally related molecules. Increasing inhibition of cell proliferation by phenyl alkanoic acids together with a decrease in cells in S phase and an increase in apoptotic cells was observed with increased chain length between four and ten carbons. Introduction of double bonds into the side chain was associated with increased growth inhibition. In contrast, 4-phenylbutyrate was a more potent inhibitor of histone deacetylase and inducer of histone acetylation than the other phenyl alkanoic acids examined. In comparison with the action of 4-phenylbutyrate, actions other than inhibition of histone deacetylase appear to be more important for growth inhibition by longer chain phenyl alkanoic and phenyl alkenoic acids.

超原子価ヨウ素試薬によるシクロプロパノール系の開裂反応とその応用

The reaction of tertiary cyclopropanol systems with hypervalent iodines in a protic solvent caused oxidative bond cleavage at C1-C2 and C2-C3 leading to alkenoic acids or their corresponding esters in high yields. In the cases of the compounds bearing an alkyl group on the cyclopropane-ring, the endo-compound gave only the (Z) -alkene while the exo-compound afforded only the (E) -alkene. A strong acid catalyst promoted these reactions. In fluorinated alcohols, the oxidation of cyclopropanol systems with phenyliodine (III) diacetate caused a mixture of enones and β-acetoxyketones. On the other hand, phenyliodine (III) bistrifluoroacetate afforded alkenoic esters. The asymmetric synthesis of (-) -pinidine and its enantiomer was achieved by starting from norgranatanone via the asymmetric enolization, stereoselective cyclopropanation, and ring cleavage of the resulting cyclopropanol system with a hypervalent iodine as key steps. Formal asymmetric synthesis of (+) -indolizidine 223 AB was also accomplished.

Iron(II)-Catalyzed Chlorolactamization of γ,δ-Unsaturated Carboxylic Acids

A one-pot chlorolactamization of γ,δ-unsaturated carboxylic acids is presented. Substrates like carboxylic acid 1 were transformed into the acyl azides which upon treatment with FeCl 2 and TMSCl in i-PrOH cyclized to yield lactams such as 2 (75% yield). The reaction yielded exclusively the syn-addition product as proven by the crystal structure of chlorolactam 2. The acyclic alkenoic acids 3-6 reacted equally well to the products 7-10 (57-81% yield). The reaction proceeded not stereospecifically but yielded a mixture of erythro- and threo-products.

Carboxylic acid clathrate hosts of Diels-Alder adducts of phencyclone and 2-alkenoic acids. Role of bidentate C-H ... O hydrogen bonds between the phenanthrene and carbonyl groups in host-host networks.

Carboxylic acid host compounds (3) having a phenanthrene-condensed bicyclo[2.2.1]hept-2-en-7-one skeleton have been synthesized by the [4 + 2]pi cycloaddition of phencyclone (1a) with 2-alkenoic acids (2) and their inclusion behavior was investigated. The endo [4 + 2]pi cycloadducts (3) enclathrated alcohols and ethers besides aromatics and ketones. The X-ray crystallographic analysis of the inclusion compound (3ac-dioxane) of the endo [4 + 2]pi cycloadduct (3ac) of phencyclone and trans 2-butenoic acid (2c) indicated that dioxanes are located at the opposite side of the bridged carbonyl of the bicyclo[2.2.1]hept-2-en-7-one moiety, in which the O-H...O and C-H...O hydrogen bonds play an important role in the inclusion complex formation. Similarly, a pair of 3-pentanone molecules were included in the endo [4 + 2] pi cycloadduct (3ae) of 1a and cinnamic acid (2e). In both cases, the hosts are linked by the edge-to-face interaction between the phenanthrene and phenyl rings and the "bidentate" C-H...O hydrogen bonds between the phenanthrene-ring hydrogens and the bridged carbonyl or the carboxylic carbonyl group. The endo [4 + 2] pi cycloadduct (3bl) of tetracyclone (1b) and acrylamide (2l) also showed a wide-range inclusion behavior, in which alcohols are included by making a hydrogen-bond loop with the amide groups. The inclusion behavior of the carboxylic acid Diels-Alder hosts is discussed on the basis of the single crystal X-ray analysis, thermal analysis and semiempirical molecular orbital calculation data.

Molecular Simulation of Chemical Structure and Biological Activity of Thromboxane Synthase Inhibitors by Multivariate Neural-network Analysis

The effect of [2-substituted-4-(3-pyridyl)-1,3-dioxan-5-yl]alkenoic acids of thromboxane synthase was examined using a multivariate quantitative structure-activity relationship (QSAR) model. As biological parameters, the dual inhibition of thromboxane receptors (inhibition of the in vitro aggregation of human platelets) and of thromboxane synthase were used. As chemical parameters, the inductive constant, van der Waals radius, the STERIMOL parameters L and B 1 of the substituents, and the dihedral angle energy of the geometry-optimized conformations of the antagonists (hybrid Gasteiger molecular-mechanics approach) were chosen. The backpropagation neural network approach has the ability to approximate multivariate structure-activity functions with satisfactory accuracy.

Asymmetric Photolysis of 2-Phenylcycloalkanones with Circularly Polarized Light: A Kinetic Model for Magnetic Field Effects

Abstract Magnetic field effects (MFE) on asymmetric photolysis involving a biradical intermediate have been investigated on a kinetic model where an intersystem crossing (ISC) of the intermediate is taken into account. Changes in the enantiomeric excesses (ee) of chiral substances with circularly polarized light (CPL) irradiation have been simulated, and the necessary conditions for observing the MFE were obtained. The asymmetric photolysis of racemic 2-phenylcycloalkanones (2-PCAs) with CPL has been carried out in both the presence and absence of a magnetic field. Since the anisotropy g factors of 2-PCAs are considerably large, the CPL-induced ee are achieved to a few percent after 90% decomposition though the MFE are not observed. The photolysis mechanism of 2-PCAs in an air-saturated solution has been also clarified. Triplet acyl–benzyl biradicals, formed via photochemical α-cleavage of 2-PCAs, react with O2 dissolved in the solution and result in the formation of acetophenone and alkenoic acids. The bimolecular reactions are diffusion-controlled and the rates are comparable to those of ISC to the singlet biradicals for all 2-PCAs. The recombination yields of the biradicals are sufficiently large. However, the biradical ISC rate shows little magnetic field dependence, which explains the absence of the MFE in this asymmetric photolysis.

FTIR study of chiral modifier–reactant interactions. The cinchonidine–alkenoic acid system

Cyclic cinchonidine ∶ acid complexes (1 ∶ 1 and 1 ∶ 2) of the chiral modifier cinchonidine (CD) and an alkenoic acid, tiglic acid, in dichloromethane solvent have been observed by FTIR spectroscopy. Both the OH and the quinuclidine N atom of CD are involved in the hydrogen bond with the acid molecule(s). Such dual-site modifier–reactant interactions play an important role in the enantioselective hydrogenation of alkenoic acids over CD-modified Pd catalysts. The stability of these 1 ∶ 1 and 1 ∶ 2 complexes has been probed by addition of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), a stronger base than CD. DBU builds ion pairs with the acid (with 1 ∶ 1 and 1 ∶ 2 stoichiometry) and a hydrogen bond with the OH of CD. However, despite the large difference in basicity between CD and DBU, 1 ∶ 2 CD ∶ acid complexes can still be detected when more than 0.5 equivalent DBU was added with respect to the acid, at which ratio the enantiomeric excess (ee) drops dramatically. Hence, the molecular structure of CD favours formation of cyclic complexes via a dual-site interaction, which is not possible for DBU ∶ acid complexes, and stabilises 1 ∶ 2 CD ∶ acid species, which are proposed to be responsible for enantiodifferentiation.

ChemInform Abstract: Two‐Carbon Homologation of Aldehydes via Silyl Ketene Acetals. Part 2. Study of the Stereochemical Control in the Formation of (E)‐Alkenoic Acids.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform Abstract: Syntheses with Perfluoroalkyl Radicals from Perfluoroalkyl Iodides. Syntheses with Perfluoroalkyl Iodides. A Review. Part 3. Addition of RFI to Norbornene Esters, Acids and Anhydrides, Alkenoic Acids and Esters, Alkenylsuccinic Anhydrides or Diesters, and to Vinyl Monomers; Lactonization and Other Reactions of Adducts; Hydroperfluoroalkylation by RFI; Synthesis and Reactions of I(CF2)nI Homologues (n = 1—3); Perfluoroalkylation of Arenes by

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Two-carbon homologation of aldehydes via silyl ketene acetals. 2. Study of the stereochemical control in the formation of (E)-alkenoic acids.

The condensation of C,O,O-tris(trimethylsilyl)ketene acetal 1 with aldehydes 2 in the presence of catalytic amounts of mercuric iodide at room temperature affords syn and anti beta-trimethylsiloxy alpha-trimethylsilyl alkanoic acid silyl esters 3 in good yields. These new compounds gave, under acidic or basic conditions, E and (or) Z enoic acids 4. The paths for the formation of these alkenoic acids are discussed.

Synthesis of Analogs of Juvenile Hormons Proceeding from Phenol Derivatives

New potential juvenoids, esters of alkenoic and alkadienoic acids with phenoxy- and phenoxyphenoxyethanol were synthesized, and also esters of phenoxyacetic acid with alkenols amd alkadienols.