17639-93-9Relevant academic research and scientific papers
Mass Spectra of Halogenated Esters. 7. Methyl Esters of 2-Chloro C2-C20 n-Alkanoic Acids
Korhonen, Ilpo O. O.
, p. 729 - 735 (1988)
The mass spectral fragmentation of a homologous series of methyl esters of 2-chloro n-alkanoic acids ranging from acetic (C2) to eicosanoic (C20) acid on electron impact has been investigated.The fragmentation pathways were elucidated with the aid of the first field-free region metastable ions, the results being presented with one compound, i.e. with ionized methyl 2-chloro-octanoate.Owing to the Cl/H exchanges and to the formation of the nonchlorinated parent esters prior to the fragmentations the spectra show the peak pairs with and without the chlorine atom.The effects become more evident with increasing chain length; shown most visually by the abundance ratios of the McLafferty rearrangement ions at m/z 108/110 and 74, and fragments at m/z 121/123 and 87.
Visible Light-Induced Oxidative Chlorination of Alkyl sp3 C-H Bonds with NaCl/Oxone at Room Temperature
Zhao, Mengdi,Lu, Wenjun
supporting information, p. 4560 - 4563 (2017/09/11)
A visible light-induced monochlorination of cyclohexane with sodium chloride (5:1) has been successfully accomplished to afford chlorocyclohexane in excellent yield by using Oxone as the oxidant in H2O/CF3CH2OH at room temperature. Other secondary and primary alkyl sp3 C-H bonds of cycloalkanes and functional branch/linear alkanes can also be chlorinated, respectively, under similar conditions. The selection of a suitable organic solvent is crucial in these efficient radical chlorinations of alkanes in two-phase solutions. It is studied further by the achievement of high chemoselectivity in the chlorination of the benzyl sp3 C-H bond or the aryl sp2 C-H bond of toluene.
Atmospheric chemistry of two biodiesel model compounds: Methyl propionate and ethyl acetate
Andersen, Vibeke F.,Berhanu, Tesfaye A.,Nilsson, Elna J. K.,Jorgensen, Solvejg,Nielsen, Ole John,Wallington, Timothy J.,Johnson, Matthew S.
experimental part, p. 8906 - 8919 (2011/10/17)
The atmospheric chemistry of two C4H8O2 isomers (methyl propionate and ethyl acetate) was investigated. With relative rate techniques in 980 mbar of air at 293 K the following rate constants were determined: k(C2H5C(O)OCH3 + Cl) = (1.57 ± 0.23) × 10-11, k(C2H5C(O) OCH3 + OH) = (9.25 ± 1.27) × 10-13, k(CH 3C(O)OC2H5 + Cl) = (1.76 ± 0.22) × 10-11, and k(CH3C(O)OC2H5 + OH) = (1.54 ± 0.22) × 10-12 cm3 molecule -1 s-1. The chlorine atom initiated oxidation of methyl propionate in 930 mbar of N2/O2 diluent (with, and without, NOx) gave methyl pyruvate, propionic acid, acetaldehyde, formic acid, and formaldehyde as products. In experiments conducted in N 2 diluent the formation of CH3CHClC(O)OCH3 and CH3CCl2C(O)OCH3 was observed. From the observed product yields we conclude that the branching ratios for reaction of chlorine atoms with the CH3-, -CH2-, and -OCH3 groups are 9 ± 2%, respectively. The chlorine atom initiated oxidation of ethyl acetate in N2/O 2 diluent gave acetic acid, acetic acid anhydride, acetic formic anhydride, formaldehyde, and, in the presence of NOx, PAN. From the yield of these products we conclude that at least 41 ± 6% of the reaction of chlorine atoms with ethyl acetate occurs at the -CH2- group. The rate constants and branching ratios for reactions of OH radicals with methyl propionate and ethyl acetate were investigated theoretically using transition state theory. The stationary points along the oxidation pathways were optimized at the CCSD(T)/cc-pVTZ//BHandHLYP/aug-cc-pVTZ level of theory. The reaction of OH radicals with ethyl acetate was computed to occur essentially exclusively (～99%) at the -CH2- group. In contrast, both methyl groups and the -CH2- group contribute appreciably in the reaction of OH with methyl propionate. Decomposition via the α-ester rearrangement (to give C2H5C(O)OH and a HCO radical) and reaction with O 2 (to give CH3CH2C(O)OC(O)H) are competing atmospheric fates of the alkoxy radical CH3CH2C(O)OCH 2O. Chemical activation of CH3CH2C(O)OCH 2O radicals formed in the reaction of the corresponding peroxy radical with NO favors the α-ester rearrangement.
Mechanism of halogen exchange in ATRP
Peng, Chi-How,Kong, Jing,Seeliger, Florian,Matyjaszewski, Krzysztof
scheme or table, p. 7546 - 7557 (2012/07/28)
Detailed mechanistic studies reveal that halogen exchange (HE) in ATRP can occur not only by a radical pathway (atom transfer) but also by an ionic pathway (SN2 reaction) because Cu(I)(L)X and Cu (II)(L)X2 complexes contain weakly associated halide anion that can participate in the SN2 reaction with alkyl halide (ATRP initiator). Both pathways were kinetically studied, and their contributions to the HE process were quantitatively evaluated for seven alkyl halides and three Cu(I)(L)Cl complexes. Radical pathway dominates the HE process for 3° and 2° alkyl bromides with more active complexes such as Cu (I)(TPMA)Cl. Interestingly, ionic pathway dominates for 1° alkyl bromides and less active ATRP catalysts. These studies also revealed that degree of association of alkyl halide anion depends on the structure of copper complexes. In addition, radical pathway is accompanied by the reverse reactions such as deactivation of radicals to alkyl bromides and also activation of alkyl chlorides, reducing the efficiency of halogen exchange.
Preparation of a mannich base intermediate for 2-[(4-heterocyclic-phenoxymethyl)-phenoxy]-alkanoates
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, (2008/06/13)
A Mannich base intermediate for 2-[(4-heterocyclic-phenoxymethyl)-phenoxyl]-alkanoates and methods for its preparation are provided. A method for preparation of an alkyl 2-[2-(secondary amino methyl)-5-alkylphenoxy]-alkanoate comprises the steps of: reacting a mixture of m-alkyl phenol, a secondary amine, and an aldehyde, with or without a catalyst, in a first solvent at reflux temperatures to form a 2-[(secondary amino)methyl]-5-alkylphenol. That product is then reacted with an alkyl 2-haloalkanoate, and an alkali metal carbonate, with or without a second catalyst in a second solvent at reflux temperatures to form the 2-[2-(secondary amino methyl)-5-alkylphenoxy]-alkanoate. The aldehyde may be paraformaldehyde, aqueous formaldehyde, formaldehyde, or polymerized acetal derivatives thereof. The first solvent may be acetonitrile or toluene. The catalyst may be an acid catalyst or a base catalyst. In the preferred embodiment the Mannich base is a 2-[(secondary amino)-methyl]-5-alkylphenol, or a 2-[2-(secondary amino methyl)-5-alkylphenoxy]-alkanoate.
Esterification of carboxylic acid salts
-
, (2008/06/13)
Mono- or polycarboxylic acid esters are prepared by reacting a salt of such carboxylic acid with an organic halocompound, e.g., a (cyclo)alkyl, (cyclo)alkenyl, aryl or aralkyl halide, in an aqueous reaction medium, in the presence of a catalytically effective amount of a phase transfer catalyst, for example an onium salt.
Empirical rules for the enantiopreference of lipase from Aspergillus niger toward secondary alcohols and carboxylic acids, especially α-amino acids
Janes, Lana E.,Kazlauskas, Romas J.
, p. 3719 - 3733 (2007/10/03)
Lipase from Aspergillus niger (ANL, Amano lipase AP) catalyzes enantioselective hydrolysis and acylation reactions. To aid in the design of new applications of this lipase, we propose two empirical rules that predict which enantiomer reacts faster. For secondary alcohols, a rule proposed previously for other lipases also works for ANL, but with lower reliability (77%, 37 of 48 examples). For carboxylic acids, we examined both crude and partially-purified ANL because commercial ANL contains contaminating hydrolases. Partial purification removed a contaminating amidase and increased the enantioselectivity of ANL toward many α-amino acids, including cyclic amino acids. Unlike other lipases, ANL readily accepts positively-charged substrates and shows the highest enantioselectivity towards α-amino acids. Although a rule based on the sizes of the substituents could not predict the fast-reacting enantiomer, a rule limited to α-amino acids did predict the fast-reacting enantiomer. We estimate that the charged α-amino group contributes a factor of 40-100 (ΔΔ≠ = 2.2-2.7 kcal/mol) to the enantioselectivity of ANL towards carboxylic acids.
Trichloroisocyanuric Acid Oxidation of 2-Chloro Aldehyde Acetals to 2-Chloro Acids Esters
Boni, Monica,Ghelfi, Franco,Pagnoni, Ugo Maria,Pinetti, Adriano
, p. 156 - 159 (2007/10/02)
2-Chloro acid methyl esters were prepared in good yields treating 2-chloro aldehyde dimethyl acetals with trichloroisocyanuric acid in DMF.Aldehyde dimethyl acetals with the 2-halogen on a tertiary carbon atom were poorly reactive and could be oxidized efficiently only after their transformation into 1,3-dioxolanes.
A NEW CHIRAL HOST COMPOUND 10,10'-DIHYDROXY-9,9'-BIPHENANTHRYL. OPTICAL RESOLUTION OF PROPIONIC ACID DERIVATIVES, BUTYRIC ACID DERIVATIVES, AND 4-HYDROXYCYCLOPENT-2-EN-1-ONE DERIVATIVES BY COMPLEXATION
Toda, Fumio,Tanaka, Koichi
, p. 1807 - 1810 (2007/10/02)
Optically active 10,10'-dihydroxy-9,9'-biphenanthryl was designed as a new chiral host compound for optical resolution of guest compounds, and was found to be wery effective for resolution of the title guest compounds.
About the Ozone Cleavage of Chloroprene and of 2-Chloro-3-methyl-1,3-butadiene in Methanol
Griesbaum, Karl,Meister, Martin
, p. 1573 - 1580 (2007/10/02)
Monoozonolyses of chloroprene (1a) and of 2-chloro-3-methyl-1,3-butadiene (1b) in methanol occur with more than 90percent at the non-chlorinated double bonds to afford the corresponding α,β-unsaturated oxo compounds 2 with selectivities of 96 and 80percent respectively.The latter subsequently react with methanol, and 2a also with the complementary fragment methoxymethyl hydroperoxide (5).The α,β-unsaturated methoxy hydroperoxides 3 which have also been obtained, are less stable than similarly structured, non-α-chlorinated methoxy hydroperoxides.Diozonolyses of 1a and 1b in methanol afforded in 50-60percent the corresponding α-oxocarboxylates (21) and/or the corresponding ketals.In addition, anomalous products were obtained viz. ca. 15percent of methyl hydroxyacetate (12d) from 1a and 1b, as well as ca. 30percent of dimethyl oxalate (27b) from 1a and ca. 35percent of methyl acetate (13) from 1b.The modes of formation of these products have been postulated according to model reactions.
