- THE LIQUID-PHASE FREE RADICAL ISOMERIZATION OF CYCLIC DIMETHYLFORMAMIDE ACETALS
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In the presence of tert-butyl peroxide, 2-dimethylamino-1,3-dioxacyclanes are converted to esters of dimethylcarbamic acid.The reaction is described by a kinetic equation for an unbranched chain reaction with quadratic chain termination.The five-membered heterocycle is more reactive than the six-membered heterocycle.The predominant site for free radical attack is the methine group adjacent to the three heteroatoms.
- Pastushenko, E. V.,Kurbanov, D.,Zlotskii, S. S.,Rakhmankulov, D. L.
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- Investigation on the formation and hydrolysis of N,N-dimethylcarbamoyl chloride (DMCC) in vilsmeier reactions using GC/MS as the analytical detection method
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The formation of N,N-dimethylcarbamoyl chloride (DMCC) in Vilsmeier reactions (VRs) and the hydrolysis of DMCC during aqueous workup were investigated. The amount of DMCC formed was dependent on the chlorination reagent. The activity order was found to be
- Stare, Martina,Laniewski, Krzysztof,Westermark, Andreas,Sjoegren, Magnus,Tian, Wei
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- A structure-reactivity correlation with three slopes in the elimination kinetics of 2-substituted ethyl N,N-dimethyl-carbamates in the gas phase
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The elimination kinetics of 17 2-substituted ethyl N,N-dimethylcarbamates in the gas phase were determined in the temperature range of 269.5-420.2°C and the pressure range of 24-186 Torr. The reactions in a static system and in the presence of a free radical inhibitor are homogeneous and unimolecular and follow a first-order rate law. The kinetics and thermodynamic parameters are described. The use of several structure-reactivity relationship methods meaningless results, except for Taft σ* values. Three good slopes are originated at σ*(CH3) = 0.00. Slope a: the 2-substituted alkyl groups gave a good straight line when log (k/kCH3) vs σ* values (ρ* = - 1.94 ± 0.30, r = 0.977 at 360°C) were plotted. Slope b: Polar2 substituents gave an approximate straight line with ρ* = - 0.12 ± 0.02, r = 0.936 at 360°C. Slope c:the correlation of multiple bonded and electron-withdrawing substituents interposed by a methylene group at the 2-position of ethyl N,N-dimethylcarbamate was found to give a very good straight line wirh ρ* = 0.49 ± 0.02, r = 0.991 at 360°C. Mechanisms are suggested on the basis of these relationships. The point position of the substituents phenyl (C6H5) and isopropenyl [CH2=C(CH3)] at the 2-position was found to fall far above the three slopes of the lines. These results are interpreted in terms of neighboring group participation of these substituents in the elimination process of the carbamates. However, the acidity of the benzylic and allylic Cβ-H bond for a six-membered cyclic transition state may not be ignored. Copyright
- Chuchani, Gabriel,Nunnez, Oswaldo,Marcano, Norka,Napolitano, Suvighey,Rodriguez, Henry,Dominguez, Marianella,Ascanio, Judany,Rotinov, Alexandra,Dominguez, Rosa M.,Herize, Armando
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p. 146 - 158
(2007/10/03)
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- Orthoamides. LII. Contributions to the synthesis of carboxylic ortho acid amides
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The formamidinium salts 11a, c as well as the nitrile 12 react with sodiumhydride/dimethylamine in the presence of trimethylborate to give the ortho formic acid amide 3a. The orthoamides 6a and 16 can be prepared from the iminium salts 15 and 14, resp. by the same procedure. Treatment of the azavinylogous formamidinium salt 15 with sodiumhydride and piperidine or morpholine in the presence of trime-thylborate affords the orthoamides 6c and 6d, resp. By transamination of the azavinylogous aminalester 5a are accessible the orthoamides 6b-d. The vinylogous orthocarbonic acid derivative 17 can be obtained from the salt 14 and sodium alcoholates. The action of sodiumhydride, dimethylamine and trimethylborate on the iminium salt 18 produces a mixture of the orthocarbonic acid derivatives 7a, 8a, 9a. When the guanidinium salt 20 is treated with the same reagents the ortho-amides 3a and 10a are obtained. The reduction of the salt 20 with sodiumhydride in the presence of several activating reagents (e.g. tetrabutyl orthotitanate, aluminiumisopropylate, trimethylborate) affords the orthoamide 3a. The reduction of the iminium salts 18 and 24 does not proceed clean, giving mixtures of various orthoformic acid derivatives. The form-amidine 25 can be prepared by reduction of the salt 15 with sodiumhydride/trimethylborate with good yields. By the action of the corresponding carbanions on the guanidinium salt 20 can be obtained the carboxylic acid orthoamides 26-33. By the same procedure the orthoamides of alkyne carboxylic acids 36a-h, j-n are accessible. Wiley-VCH Verlag GmbH, 2000.
- Kantlehner, Willi,Stieglitz, Ruediger,Hauber, Michael,Haug, Erwin,Regele, Claudia
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p. 256 - 268
(2007/10/03)
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- Correlation of the Rates of Solvolysis of N,N-Dimethylcarbamoyl Chloride
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A correlation, using the extended Grunwald-Winstein equation, of the specific rates of solvolysis of N,N-dimethylcarbamoyl chloride in 21 solvents at 25.0°C demonstrates an appreciable sensitivity toward changes in both solvent ionizing power (YCl) and solvent nucleophilicity (NT), with an m value of 0.74 and an / value of 0.61.
- Kevill, Dennis N.,Oldfield, Andrew J.,D'Souza, Malcolm J.
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p. 122 - 123
(2007/10/03)
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- Alkali-metal-assistent Transfer of the Carbamte Group from Phosphocarbamates to Alkyl Halides: a New Easy Way to Alkali-metal Carbamates and to Carbamate Esters
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Phosphocarbamates P(O2CNR2)x(NR2)3-x (R=alkyl; x=1 or 2), easily obtainable by insertion of CO2 in the P-N bond of the corresponding aminophosphines P(NR2)3, have been used as a source of carbamate groups in the reaction with alkyl halides, R'X to afford carbamate esters.The reaction is mediated by alkali-metal halides, MY, and requires the presence of a suitable macrocyclic polyether (L).The overall reaction occurs in two steps: the carbamic group is first tranferred to the alkali-metal cation to give a carbamate salt which then reacts with the alkyl halide affording R2NC(O)OR'.The yield and selectivity to the carbamate ester are remarkably influenced by the nature of MY.The influence of the nature of the alkali-metal salt in the overall process and the role of the macrocyclic ligand in modifying the reactivity of the R2NCO2- anion in akli-metal carbamates are discussed.
- Aresta, Michele,Quaranta, Eugenio
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p. 1893 - 1900
(2007/10/02)
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- Chemical Ionization Mass Spectra of Urethanes
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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.
- Wright, Andrew D.,Bowen, Richard D.,Jennings, Keith R.
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p. 1521 - 1528
(2007/10/02)
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- Low-energy, Low-temperature Mass Spectra. 10-Urethanes
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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.
- Bowen, Richard D.,Maccoll, Allan
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p. 113 - 122
(2007/10/02)
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- 3-phenyl-2-propeneamine derivatives, their preparation and compositions containing them
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The invention provides compounds of formula: STR1 in which R=H, halogen, alkyl, alkyloxy, alkythio, NH2, alkylamino, dialkylamino or CF3, R3 =H or alkyl, either R4 and R5 =H and R1 and R2 =H or alkyl, optionally substituted by alkenyl (2 to 4 C) or alternatively R1 and R2 form together a saturated heterocyclic ring containing 4 to 7 ring members and optionally containing another heteroatom such as O, S or N optionally substituted by alkyl, or R4 =H, R1 =H or alkyl and R2 and R5 together form an alkylene (3 to 4 C) radical and (i) either A=alkyl or phenyl which is unsubstituted or substituted by one or two substituents chosen from halogen, alkyl, alkyloxy, alkylthio, NH2, alkylamino, dialkylamino, NO2 or CF3 or alternatively A=pyridyl, benzyl or cycloalkyl (3 to 6C), Y=S, SO or SO2 or a radical: STR2 in which R6 =H or alkyl and R7 =H or alkylcarbonyl, alkyloxycarbonyl, alkylaminocarbonyl or benzoyl, optionally substituted by one or two halogen, alkyl, alkyloxy, alkylthio, NH2, alkylamino, dialkylamino, NO2 or CF3 groups, (ii) or Y and A together form a 1-hydroxycycloalkyl radical, the ring of which contains 5 or 6 C, optionally joined to a benzene ring, it being understood that the alkyl radicals and alkyl parts contain 1 to 4 C as a straight or branched chain, and that the invention relates to all the possible geometric and optical isomers as well as their mixtures. These compounds are useful as antidepressants.
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- Orthoamides, XXXVIII. - Contributions to the Chemistry of Orthocarbonic Acid Esters and α,α,α-Trialkoxyacetonitriles
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The reactivity of the orthocarbonates 4 and the nitriles 1 has been investigated.Carboxylic acids are esterified by 4b. Orthocarbonates 4c-f and 9b are prepared by transesterification of 4b.Mixed substituted orthocarbonates 8c-f are obtained from the nitriles 1a,b.The nitriles 2a and 3a react with alkali alcoholate in alcohol to yield the orthocarbamic acid esters 13a,b. Spirocyclic orthocarbonates 17a-d are prepared from 4b and 1,2 or 1,3-dioles, respectively. The reaction of phenol with 1b affords the mixed substituted orthocarbonate 18a. Catechol is converted by 1a into the orthocarbonate 20a.Reactions of 4b with amines and ami ne derivatives are studied. In the course of these investigations guanidines 21, imidocarbonic acid esters 22a-c, 30, carbamic acid esters 25, ureas 26, the isourea derivative 29, as well as the 1,3,4-oxadiazole 31 are prepared. The mechanism of these reactions is discussed. Imidocarbonic acid esters 22d-f, 38, N-cyanocarbamates 39, and isoureas 37 can be prepared from 1b and amines or amine derivatives. 2a as well as 13b react with cyanamide to give the N-cyanoisourea 40. Ureas 26 are formed in the reaction of 1a,b with secondary amines at elevated temperatures.The guanidinium cyanide 41a can be obtained by reaction of pyrrolidine with 1b in ether, whereas under similiar conditions from 1a and pyrrolidine the amidine 42 is produced. o-Aminophenol, o-phenylenediamine and anthranilic acid are cyclized by 4b or 1b to afford the heterocyclic compounds 43-45. α- and β-amino acids are transformed by 4b or 1b into the N-(ethoxycarbonyl)amino acid esters 46 and 47, respectively.
- Kantlehner, Willi,Maier, Thomas,Loeffler, Wolfgang,Kapassakalidis, Joanis J.
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p. 507 - 529
(2007/10/02)
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- Orthoamides, XXXV. - Preparation of O,N-Functional Trisubstituted Acetonitriles
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Trichloroacetonitrile (7) reacts with molar amounts of alcoholates in alcohols to give mixtures of orthocarbonates 10 and trichloroacetimidates 9.The action of 7 on 3 moles of sodium ethoxide in heptane affords triethoxyacetonitrile 3b among other products, such as 9b, 10b and the imidate 12.The nitrile 3a can be obtained from 7 and sodium methoxide in ether in moderate yields. - The orthocarbonic acid derivatives 10b, 20a and 21a are transformed by acyl cyanides into the nitriles 3b, 4a, and 5a, respectively.N,N,N',N',N'',N''-hexamethylguanidinium cyanide (23a) is f ormed in the reaction of 22 with acetyl cyanide. - The salts 30a-32a react with alkali cyanides to form the nitriles 3b, 4a, and 5a, respectively.The nitrile 2a transfers cyanide ions to the carbenium ions 30a and 31a to yield the nitriles 3b and 4a, respectively.
- Kantlehner, Willi,Maier, Thomas,Kapassakalidis, Joannis J.
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- Reaction of 1,1-Disubstituted Hydrazines with Diethyl Azodicarboxylate
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The reaction of hydrazine derivatives 1 with diethyl azodicarboxylate (2) gives primarily the aminonitrenes 3, which add to the azodicarboxylate 2 forming the instable aminoazimines 7.These decompose by rearrangement to urethanes 8 and azidoformic acid ester 9.Furthermore the tetrazenes 5 are formed.The amount of 5 depends on the reaction conditions.
- Fahr, Egon,Koch, Karl-Heinz
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p. 219 - 222
(2007/10/02)
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- Production of isocyanates
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A furoxan, especially one in which the furoxan ring is fused to a strained aliphatic ring system, is heated in the presence of sulphur dioxide to give an isocyanate. The process enables furoxans, such as dicyclopentadiene furoxan, which ring-open at temperatures 180° C to be converted into isocyanates. In the absence of sulphur dioxide, may be difficult to control the reaction and, in some cases, no isocyanate is obtained. Diisocyanates prepared by the process may be converted into polyurethanes by reaction with suitable hydroxylic compounds.
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