- Organoboranr-Catalyzed anti-Markownikoff Hydration of Olefins
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A new, catalytic procedure for the anti-Markownikoff hydration of olefins in the presence of organoborane catalyst and dichloroaluminum hydride under dry air has been described.
- Maruoka, Keiji,Sano, Hiromi,Shinoda, Kiyotaka,Yamamoto, Hisashi
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- The hydrolysis of C12 primary alkyl sulfates in concentrated aqueous solutions. Part 2. Influence of alkyl structure on hydrolytic reactivity in concentrated aqueous mixtures of sodium primary alkyl sulfates: 1-benzoyl-3-phenyl-1,2,4-triazole as a probe of water activity
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The kinetics of the hydrolysis of aqueous solutions of three sodium C12-alkyl sulfates (SXS), sodium 2-methyl- undecyl sulfate (SMS), sodium cycloundecylmethyl sulfate (SCS) and sodium 2-pentylheptyl sulfate (SPS), has been investigated at concentrations up to 70% and compared with the behaviour of sodium dodecyl sulfate (SDS). The same kinetic form as previously described for SDS was observed, namely, autocatalysis by protons generated via hydrogen sulfate ion, but there were substantial variations in the reactivity as the alkyl structure changed; β-branching reduced the reactivity, particularly for SMS which was the least reactive of the surfactants studied. The patterns of reactivity by the uncatalysed and hydrogen-ion catalysed pathways for the different SXS were rather similar, but it is argued that the results are consistent with an SN2 mechanism for uncatalysed hydrolysis and the concerted SO3 cleavage (or transfer to a pre-associated water molecule)/proton transfer mechanism for the catalytic route, as previously proposed for SDS. Changes in the microenvironment of the sulfate group in aggregates formed from the different SXS are seen as being responsible for much of the rate variation. Attempts have been made to establish the dependence of observed rate constants in dilute solutions of SXS above the c.m.c. on the water activity as indicated empirically by the rate of pH-independent hydrolysis of 1-benzoyl-3-phenyl-1,2,4-triazole (BPT) in the same solutions. It appears, however, that BPT hydrolysis is not a useful guide to water activity in SXS solutions and values of d(ln k)/d(ln [H2O]) are generally much larger than expected on the basis of simple ideas of transition state composition. The effects of surfactant aggregation on the microenvironment in which chemical reactions take place are suggested to be the dominant kinetic influence both on SXS and BPT hydrolysis.
- Bethell,Fessey,Engberts,Roberts
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- Identification and Synthesis of Branched Wax-type Esters, Novel Surface Lipids from the Spider Argyrodes?elevatus (Araneae: Theridiidae)
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The analysis of cuticular extracts from the kleptoparasitic spider Argyrodes?elevatus revealed the presence of unusual esters, new for arthropods. These novel compounds proved to be methyl-branched long-chain fatty acid esters with methyl branches located either close or remote from the internally located ester group. The GC/MS analysis of the prosoma lipid blend from the male cuticle contained one major component, undecyl 2-methyltridecanoate (1). In contrast, four major wax-type esters, 2-methylundecyl 2,8-dimethylundecanoate (2), 2,8-dimethylundecyl 2,8-dimethylundecanoate (3), heptadecyl 4-methylheptanoate (4), and 14-methylheptadecyl 4-methylheptanoate (5), were identified in the lipid blend of female prosomata. Structure assignments were based on mass spectra, gas chromatographic retention indices, and microderivatization. Unambiguous proof of postulated structures was ensured by an independent synthesis of all five esters. Preferentially, odd-numbered carbon chains pointed to a distinct biosynthetic pathway, different from that of common fatty acids, because one or two C3 starter units are incorporated during the biosynthesis of all acid and alcohol building blocks present in the five esters. The striking sexual dimorphism together with the unique biosynthesis points to a function of the esters in chemical communication of the spiders, although no behavioral data are currently available to test this assumption.
- Chinta, Satya Prabhakar,Goller, Stephan,Uhl, Gabriele,Schulz, Stefan
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- An Intramolecular Iodine-Catalyzed C(sp3)?H Oxidation as a Versatile Tool for the Synthesis of Tetrahydrofurans
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The formation of ubiquitous occurring tetrahydrofuran patterns has been extensively investigated in the 1960s as it was one of the first examples of a non-directed remote C?H activation. These approaches suffer from the use of toxic transition metals in overstoichiometric amounts. An attractive metal-free solution for transforming carbon-hydrogen bonds into carbon-oxygen bonds lies in applying economically and ecologically favorable iodine reagents. The presented method involves an intertwined catalytic cycle of a radical chain reaction and an iodine(I/III) redox couple by selectively activating a remote C(sp3)?H bond under visible-light irradiation. The reaction proceeds under mild reaction conditions, is operationally simple and tolerates many functional groups giving fast and easy access to different substituted tetrahydrofurans.
- Br?se, Stefan,Koch, Vanessa
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supporting information
p. 3478 - 3483
(2021/07/22)
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- POLYOL ETHERS AND PROCESS FOR MAKING THEM
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New polyol ether compounds and a process for their preparation. The process comprises reacting a polyol, a carbonyl compound, and hydrogen in the presence of hydrogenation catalyst, to provide the polyol ether. The molar ratio of polyol to carbonyl compound in the process is greater than 5:1.
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Paragraph 0080
(2011/05/14)
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- POLYOL ETHERS AND PROCESS FOR MAKING THEM
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New polyol ether compounds and a process for their preparation. The process comprises reacting a polyol, a carbonyl compound, and hydrogen in the presence of hydrogenation catalyst, to provide the polyol ether. The molar ratio of polyol to carbonyl compound in the process is greater than 5:1.
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Page/Page column 8
(2010/03/31)
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- Compounds having protected hydroxy groups
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The present invention relates to compounds with protected hydroxy groups of formula (I) These compounds are precursors for organoleptic agents, such as fragrances, and masking agents and for antimicrobial agents. When activated, the compounds of formula (I) are cleaved and form one or more organoleptic and/or antimicrobial compounds.
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- Beta-ketoester compounds
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The beta-ketoesters of formula I are useful as precursors for organoleptic compounds, especially for flavors, fragrances and masking agents and antimicrobial compounds.
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- Ketone precursors for organoleptic compounds
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The invention discloses ketones of formula I: wherein, Y is an optionally substituted alkyl, cycloalkyl, or cycloalkylalkyl, wherein each alkyl group is straight or branched and each alkyl and cycloalkyl group is saturated or unsaturated; R1is hydrogen or a C1-6alkyl group that is substituted, saturated or unsaturated, straight or branched; A is a chromophoric substituted aromatic ring or ring system; n is an integer; and with the proviso that formula I is not 2-ethoxy-1-phenyl-ethanone. These compositions are useful for the delivery of organoleptic compounds, especially of flavors, fragrances, masking agents and antimicrobial compounds.
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- Preparation of optically active 2-(trifluoromethyl)alkan-1-ols by catalytic asymmetric hydrogenation
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The hydrogenation of (E)-2-(trifluoromethyl)alk-2-en-1-ols catalyzed by Ru-BINAP and Rh-BINAP has been carried out with good enantiomeric excess (71percent-83percent ee).Ru-BINAP-catalyzed hydrogenation converted 2-trifluoromethylacrylic acid to the corresponding saturated acid, the esterification and reduction of which gave optically active 2-(trifluoromethyl)propan-1-ol in 80percent ee.
- Iseki, Katsuhiko,Kuroki, Yoshichika,Nagai, Takabumi,Kobayashi, Yoshiro
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- Novel conversion of aldehydes to boronic esters. Simultaneous IGOR2 computer generation and experimental observation of an unusual rearrangement of 0α-aminoboranes
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Utilization of the IGOR2 (Interactive Generation of Organic Reactions 2) program to study the addition of the boron-hydrogen bond to various carbon-carbon and carbon-heteroatom double bonds is reported. The IGOR2 program not only generated a number of hydroboration reactions but also indicated an unusual rearrangement of α-aminomonoalkylboranes to the corresponding B-(dialkylamino)monoalkylboranes. Independent and simultaneous experimental observation of these IGOR2-generated rearrangements was made during the hydroboration of β,β-disubstituted morpholino and piperidino enamines. Thus, the hydroboration of 2-ethyl-l-morpholino-1-butene using borane-methyl sulfide (BMS) gave B-morpholinoborane as a byproduct. Additionally, upon oxidation, 2-ethyl-1-butanol was isolated from the reaction mixture. These results are explained in terms of unusual rearrangements of the α-(dialkylamino)monoalkylborane intermediate. The use of BH3-THF-BF3-OEt2 or NaBH4-BF3OEt2 for the hydroboration permits the utilization of any β, γ-disubstituted enamine in this rearrangement reaction and vastly improves the yields of the rearrangement products. Nonoxidative workup of the rearrangement reaction mixture affords excellent yields of the corresponding boronic acids, which were isolated as 2-alkyl-1,3,2-dioxaborinanes.
- Fisher, Gary B.,Juarez-Brambila, Jesus J.,Gorakki, Christian T.,Wipke, W. Todd,Singaram, Bakthan
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p. 440 - 444
(2007/10/02)
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- PRODUCTION OF METHYL 2-METHYLENE-5,10-UNDECADIENOATE FROM BUTADIENE AND METHYL METHACRYLATE AT A HOMOGENEOUS COMPLEX NICKEL CATALYST AND SOME OF ITS TRANSFORMATIONS
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A method was developed for the production of methyl 2-methylene-5,10-undecadienoate from butadiene and methyl methacrylate at a homogeneous complex nickel catalyst.Methyl 1,6-trans-9-cis/trans,13-trans,18-nonadecapentaene-10-carboxylate is formed as side product. 2-Methylundecanal (having a fragrant odor), 2-methyl-1-undecanol, 2-nonyl-1-undecanol, and 2-methylene-5,10-undecadienoic acid, which have found use in the formulation of medicinal products, were obtained from these esters by various transformations.
- Zakharkin, L. I.,Guseva, V. V.,Kamernitskii, D. A.
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p. 1056 - 1059
(2007/10/02)
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- Application de la reaction de Guerbet a la methylation de n-alcanols primaires
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The Guerbet reaction is applied to the methylation of different primary n-alkanols.For 1-n-undecanol 1, selectivities of 70 to 80 percent in 2-methylation are obtained using an excess of methanol, sodium or sodium methoxide as bases and nickel or palladium as catalysts.These transformations which were extended to other primary n-alkanols are obtained at lower temperatures (160-200 deg C) than in the described hitherto conditions.Industrial applications of this Guerbet reaction could be of great interest in these simpler experimental conditions.
- Sabadie, Jean,Descotes, Gerard
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p. 253 - 256
(2007/10/02)
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