3553-80-8Relevant articles and documents
Utilization of microwave heating in the McMurry reaction for facile coupling of aldehydes and ketones to give alkenes
Stuhr-Hansen, Nicolai
, p. 5491 - 5494 (2007/10/03)
Microwave heating was applied in high-yield syntheses of alkenes by McMurry coupling of aldehydes and ketones with low-valent titanium. All aldehydes and ketones including sulfur end-capped analogues gave alkenes in isolated yields above 80% without detectable amounts of pinacols.
Gas-phase elimination kinetics of ethyl, isopropyl and tert-butyl N,N-diethylcarbamates. Application of Taft-Topsom correlation for substituents other than carbon at the acid side of organic ethyl esters
Herize, Armando,Dominguez, Rosa M.,Rotinov, Alexandra,Nunez, Oswaldo,Chuchani, Gabriel
, p. 201 - 206 (2007/10/03)
The elimination kinetics of ethyl, isopropyl and tert-butyl N,N-diethylcarbamates were investigated in a static reaction vessel over the temperature range 220-400°C and pressure range 17-160 Torr. These reactions are homogeneous, unimolecular and follow a first-order rate law. The temperature dependance of the rate coefficients is given by the following equations: for ethyl N,N-diethylcarbamate, log k1 (s-1) = (11.47 ± 0.25) - (178.4 ± 3.1) kJ mol-1 (2.303 RT)-1, for isopropyl N,N-diethylcarbamate, log k1 (s-1) = (12.83 ± 0.70) - (179.8 ± 7.9) kJ mol-1 (2.303 RT)-1; and for tert-butyl N,N-diethylcarbamate, log k1 (s-1) = (12.87 ± 0.62) - (158.6 ± 6.2) kJ mol-1 (2.303 RT)-1. The branching of the alkyl groups at the alcohol side of the ester exerts a significant effect on the rates in the order tert-butyl > isopropyl > ethyl. In addition, the presence of different substituents other than carbon at the acid side of organic ethyl esters gives the best correlation when using the Taft-Topsom equation: log k/kH = -(0.68 ± 0.12)σs + (2.57 ± 0.12)σF - (1.18 ± 0.27)σR (r = 0.984 ± 0.119 at 400°C). According to this relationship, the field (inductive) effect of the substituent has the greatest influence on rate enhancement, while the polarizability (steric) and resonance factors, although small in effect, favour the elimination process. Copyright
A novel synthesis of dialkyl carbonates from carbon dioxide, alcohols, and tert-amines mediated by acetylene
Sasaki, Yoshiyuki
, p. 825 - 826 (2007/10/03)
A novel acetylene-mediated reaction of carbon dioxide with alcohols and tert-amines leads to effective formations of dialkyl carbonates and alkyl N,N-dialkylcarbamates without catalyst.
REACTIVITY OF COORDINATED LIGANDS. METAL-ASSISTED ELECTROPHILIC REACTIONS AT THE O-COORDINATED CARBON DIOXIDE FRAGMENT OF THE N,N-DIALKYLCARBAMATO GROUP: FORMATION AND DECOMPOSITION OF MIXED N,N-DIALKYLCARBAMIC ANHYDRIDES, R2NC(O)O-E
Belforte, Antonio,Dell'Amico, Daniela Belli,Calderazzo, Fausto,Giurlani, Ugo,Labella, Luca
, p. 119 - 127 (2007/10/02)
N,N-Dialkylcarbamato complexes, , of sodium, copper(II), manganese(II), cobalt(II), titanium(III), vanadium(III) and iron(III) react with electrophilic reagents under mild conditions giving the products arising from the attack at the oxygen atom of the metal-coordinated carbamato group. Thus, for example, acyl halides R'COCl give the mixed carbamic-carboxylic anhydrides R2N-C(O)O-C(O)R', independent of the nature of the metal, either as an unstable intermediate or as a kinetically-controlled product (R = i-Pr, R' = Me, Ph). Vanadium(III), titanium(III) and iron(III) dialkylcarbamato complexes react incompletely with R'COCl, giving chloro-dialkylcarbamato metal complexes. The manganese(II) diethylcarbamato derivative reacts with ClCOOEt, COCl2, ClSOOEt, SOCl2 or ClP(OEt)2; in these cases, experimental evidence exists that the organic halides react in a way similar to R'COCl, i.e. via O-functionalization of the manganese-coordinated diethylcarbamato group and formation of an Et2NC(O)OE-type compound with E=COOEt, COCl, SOOEt, SOCl, P(OEt)2. The mechanism of Et2NC(O)OE decomposition has been investigated by examining the reaction of the 13C-labelled Mn6(O2CNEt2)12 with MeCOCl, COCl2, ClCOOEt or ClSOOEt. The IR spectroscopic and GC-mass analysis of the reaction mixtures showed loss of 13CO2, while the organic product was unlabelled. This can only be consistent with the cleavage of the RN-13C bond within the intermediate anhydride. A classification of metal-assisted reactions is presented in the Appendix.
Chemical Ionization Mass Spectra of Urethanes
Wright, Andrew D.,Bowen, Richard D.,Jennings, Keith R.
, p. 1521 - 1528 (2007/10/02)
Chemical ionization mass spectra using methane as the reagent gas are reported for 33 urethanes of general structure RNHCO2C2H5 nH2n+1 (n=1-8), CH2CH=CH2, cyclo-C6H11, Ph, PhCH2, PhCH2CH2, and Ph(CH3)CH> and R2NCO2C2H5 nH2n+1 (n=1-4)>.Abundant MH+ ions are present in all the spectra, accompanied by satellite peaks corresponding to + and +.Four classes of fragment ions are of general importance in the spectra.Two of these, + and +, are associated with the CO2C2H5 group.The other two, corresponding to alkane and alkene elimination from MH+, arise from the RNH or R2N function.The mechanisms whereby these fragment ions are formed are discussed and their analytical utility is illustrated by reference to the spectra of the four isomeric C4H9NHCO2C2H5 and the eight isomeric C5H11NHCO2C2H5 compounds.The results of 2H-labelling studies are presented and a comparison is made between the methane and ammonia chemical ionisation spectra of selected urethanes.
Low-energy, Low-temperature Mass Spectra. 10-Urethanes
Bowen, Richard D.,Maccoll, Allan
, p. 113 - 122 (2007/10/02)
The 12.1 eV, 75 deg C electron impact mass spectra of 24 urethanes, RNHCO2C2H5 nH2n+1 (n = 1-8), CH2=CHCH2, Ph, PhCH2 and PhCH2CH2>, and seven symmetrically disubstituted urethanes R2NCO2C2H5 (R = CnH2n+1 (n = 1-4) are reported and discussed.All 31 spectra show appreciable molecular ion peaks.For n-CnH2n+1NHCO2C2H5, M+. usually is the most abundant ion in the spectrum.A peak at m/z 102 of comparable intensity also is present; this corresponds to formal cleavage of the bond connecting the α- and β-carbon atoms in the N-alkyl group, though it is unlikely that the daughter ion has the structure (1+).In the RNHCO2C2H5 series, branching at the α-carbon atom enhances the relative abundance of the ion arising by notional α-cleavage at the expense of that of M+..Formal cleavage of the bond between β- and γ-carbon atoms occurs to some extent for +. ions; this reaction provides information on the degree of branching at the β-carbon, especially if metastable molecular ions are considered.The higher n-CnH2n+1NHCO2C2H5 (n = 5-8) urethanes exhibit two other significant ions in their mass spectra.First, there is a peak at (1+).Secondly, a peak is present at m/z 90; the most plausible structure for this ion is (1+), arising by double hydrogen transfer from the alkyl group and expulsion of a nH2n-1>. radical.Ions originating from secondary decomposition of the primary ionic species are generally of only very low abundance in these spectra.
Novel Synthesis of Carbamic Ester from Carbon Dioxide, Amine, and Ortho Ester
Ishii, Shideru,Nakayama, Hidenobu,Yoshida, Yasuhiko,Yamashita, Tadataka
, p. 455 - 458 (2007/10/02)
Carbon dioxide reacted with aliphatic amines and ortho esters to form carbamic esters in good yields.The influence of different ortho esters on the carbamate synthetic reaction is described.In the case of orthocarbonates, carbamic esters were obtained in high yields.The reaction of carbon dioxide, amines, and ortho esters may involve a competitive reaction between the esterification of carbamic acid produced by a reaction of carbon dioxide with amine, and the alkylation of amine.
Novel Synthesis of Carbamate Ester from Carbon Dioxide, Amines, and Alkyl Halides
Yoshida, Yasuhiko,Ishii, Shigeru,Watanabe, Masayo,Yamashita, Tadataka
, p. 1534 - 1538 (2007/10/02)
A novel synthesis of carbamate ester using carbon dioxide as a direct material is reported in this article.The direct reaction of carbon dioxide, aliphatic amines, and alkyl halides was found to give the corresponding alkyl carbamate esters in good yields.Reactions using secondary alkyl bromides gave carbamate esters in higher yields than those using primary or tertiary alkyl bromides.The carbamate ester yields increased with the addition of N,N-dimethylformamide to the reaction system of carbon dioxide, amines, and alkyl halides.This reaction is considered to prooced by an SN2 displacement reaction of the alkyl halide by the carbamate anion formed from the reaction of carbon dioxide and the amine.
A Convinient Preparative Method of Nitrile Oxides by the Dehydration of Primary Nitro Compounds with Ethyl Chloroformate or Benzenesulfonyl Chloride in the Presence of Triethylamine
Shimizu, Tomio,Hayashi, Yoshiyuki,Shibafuchi, Hiroshi,Teramura, Kazuhiro
, p. 2827 - 2832 (2007/10/02)
Three nitrile oxides (MeOCOCN->O, PhCN->O, and EtCN->O) were effectively generated in situ by dehydration of the corresponding primary nitro compounds (RCH2NO2) with PhSO2Cl or ClCOOEt in the presence of triethylamine.Various cycloadducts were prepared by the reaction of them with dipolarophiles.Some advantages of these methods are described in comparison with other known methods.
