Hydrogenolysis of nitrogen-containing compounds on a cobalt-molybdenum catalyst

1979 ◽  
Vol 44 (1) ◽  
pp. 85-98 ◽  
Author(s):  
Mirko Černý
Keyword(s):  
Nitrogen Atom ◽  
Methyl Groups ◽  
Molybdenum Catalyst ◽  
Methyl Group ◽  
Cobalt Molybdenum Catalyst ◽  
Methylene Groups ◽  
Methyl Derivatives ◽  
Nitrogen Containing Compounds

A sulphidized cobalt-molybdenum catalyst on Al2O3 has been used to study hydrogenolysis of pyridine, piperidine, quinoline and their methyl derivatives. In reaction mixtures were identified the compounds which contribute to the knowledge of the mechanism of hydrogenolysis. The cleavage of 2-methylpiperidine ring takes place between the nitrogen atom and the methylene groups and not between the nitrogen atom and the carbon substituted with the methyl group. The amount of hydrogenolysis products decreases in the series pyridine, 2-methylpyridine, 2,6-dimethylpyridine and 2,4,6-trimethylpyridine, i.e. with the increasing number of the methyl groups bonded to the ring.

An anomalous effect of methyl group on acidity of acylthioureas

1987 ◽  
Vol 52 (8) ◽  
pp. 1992-1998 ◽  
Author(s):  
Jaromír Kaválek ◽  
Josef Jirman ◽  
Vladimír Macháček ◽  
Vojeslav Štěrba
Keyword(s):  
Hydrogen Atom ◽  
Rate Constant ◽  
Rate Constants ◽  
Dissociation Constants ◽  
Acetyl Derivative ◽  
Methyl Groups ◽  
Anomalous Effect ◽  
Methyl Group ◽  
Methyl Derivatives

Dissociation constants and methanolysis rate constants have been measured of 1-acetyl- and 1-benzoylthioureas and their N-methyl derivatives. Replacement of hydrogen atom at N(1) (next to the acyl group) by methyl group increases the acidity of the benzoyl derivative by one order, that of the acetyl derivative by as much as two orders of magnitude. Replacement of both hydrogens at N(3) by methyl groups lowers the methanolysis rate constant by more than two orders, whereas the replacement of hydrogen atom at N(1) by methyl group increases the methanolysis rate by the factor of 30.

THE INFRARED ABSORPTION SPECTRA OF DEUTERATED ESTERS: III. METHYL LAURATE

1962 ◽  
Vol 40 (2) ◽  
pp. 301-320 ◽  
Author(s):  
R. Norman Jones
Keyword(s):  
Absorption Spectrum ◽  
Infrared Absorption ◽  
Carbon Disulphide ◽  
Infrared Absorption Spectrum ◽  
Methyl Laurate ◽  
Methyl Groups ◽  
Acid Chlorides ◽  
Methyl Group ◽  
Methylene Groups ◽  
Infrared Absorption Spectra

The infrared absorption spectrum of methyl laurate in carbon tetrachloride and carbon disulphide solutions has been compared with the spectra of seven derivatives deuterated in the ω-methyl group, the α-methylene groups, the carbomethoxy group, and in binary and ternary combinations of these positions. The spectra of n-dodecanes deuterated in the terminal methyl groups and of methyl laurates chlorinated in the ω-methyl and α-methylene groups have also been measured.From an analysis of these spectra, all the bands and inflections between 3100 and 700 cm−1 in the spectrum of methyl laurate can be assigned to localized group vibrations. The spectra of some related acid chlorides, alcohols, and bromides are also briefly noted.

scholarly journals Stereochemistry of the incorporation of valine methyl groups into methylene groups in cephalosporin C.

1984 ◽  
Vol 222 (3) ◽  
pp. 777-788 ◽  
Author(s):  
C P Pang ◽  
R L White ◽  
E P Abraham ◽  
D H G Crout ◽  
M Lutstorf ◽  
...  
Keyword(s):  
Side Chain ◽  
Methyl Groups ◽  
Cephalosporin C ◽  
Cephalosporium Acremonium ◽  
Methyl Group ◽  
Methylene Groups ◽  
Methylene Group

‘Chiral methyl valines’, i.e. samples of valine labelled stereospecifically in the methyl groups with 2H and 3H, were incorporated into cephalosporin C by a suspension of washed cells of Cephalosporium acremonium. Analysis by 3H n.m.r. of the cephalosporin C produced showed that the conversion of the 3-pro-S-methyl group of valine into the acetoxymethyl side-chain was a highly stereospecific process. By contrast, conversion of the 3-pro-R-methyl group into the endocyclic methylene group of the dihydrothiazine ring was shown to proceed by a non-stereospecific process.

Sigma and Pi Electron Contributions to Long-range Spin–Spin Coupling Constants in the Methyl Derivatives of the Fluoropyridines

1972 ◽  
Vol 50 (14) ◽  
pp. 2344-2350 ◽  
Author(s):  
J. B. Rowbotham ◽  
T. Schaefer
Keyword(s):  
Nitrogen Atom ◽  
Long Range ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Coupling Mechanism ◽  
Methyl Group ◽  
Spin Coupling Constants ◽  
Methyl Derivatives ◽  
Spin Spin Coupling ◽  
Derivatives Of

Seven methyl derivatives of the 3- and 4-fluoropyridines are synthesized and their p.m.r. spectra are analyzed. The nuclear spin–spin coupling constants are compared with previous results for the four methyl derivatives of 2-fluoropyridine. A model in which the nitrogen atom polarizes primarily the σ electron system of the ring, leaving the π electron contribution to the coupling mechanism relatively unaffected, qualitatively accounts for the large majority of the coupling constants. For example, the coupling over six bonds between methyl protons and a fluorine nucleus, [Formula: see text] is the same whether the fluorine atom or the methyl group is placed ortho to the nitrogen atom and is little different from its value in p-fluorotoluene. The model is consistent with significant σ electron contributions to long-range couplings over four and five bonds from methyl protons to fluorine nuclei or ring protons. Evidence is adduced for resonance structures in which fluorine conjugates with nitrogen or with ring carbon atoms. An earlier suggestion, that hyperconjugation of the methyl group with nitrogen is necessary to the interpretation of the observed couplings, is dropped. Instead, a substantial polarization of the σ electron core near C-2 and -6 is invoked but apparently does not extend appreciably beyond these atoms in the ring.

Kinetics of the catalytic hydrodesulphurization reaction system; hydrogenolysis of thiophene

1980 ◽  
Vol 45 (10) ◽  
pp. 2728-2741 ◽  
Author(s):  
Pavel Fott ◽  
Petr Schneider
Keyword(s):  
Atmospheric Pressure ◽  
Active Sites ◽  
Flow Reactor ◽  
Kinetic Equations ◽  
Reaction System ◽  
Reaction Products ◽  
Molybdenum Catalyst ◽  
Cobalt Molybdenum Catalyst ◽  
Kinetics Of ◽  
Reaction Schemes

Kinetics have been studied of the reaction system taking place during the reaction of thiophene on the cobalt-molybdenum catalyst in a gradientless circulation flow reactor at 360 °C and atmospheric pressure. Butane has been found present in a small amount in the reaction products even at very low conversion. In view of this, consecutive and parallel-consecutive (triangular) reaction schemes have been proposed. In the former scheme the appearance of butane is accounted for by rate of desorption of butene being comparable with the rate of its hydrogenation. According to the latter scheme part of the butane originates from thiophene via a different route than through hydrogenation of butene. Analysis of the kinetic data has revealed that the reaction of thiophene should be considered to take place on other active sites than that of butene. Kinetic equations derived on this assumption for the consecutive and the triangular reaction schemes correlate experimental data with acceptable accuracy.

Dirhodium-Catalyzed Chemo- and Site-Selective C–H Amidation of N,N-Dialkylanilines

Synlett ◽  
2020 ◽  
Author(s):  
Yoshihiro Ueda ◽  
Gong Chen ◽  
Kenta Arai ◽  
Kazuhiro Morisaki ◽  
Takeo Kawabata
Keyword(s):  
Nitrogen Atom ◽  
Aromatic Ring ◽  
Methyl Group ◽  
Site Selective

AbstractA method for dirhodium-catalyzed C(sp3)–H amidation of N,N-dimethylanilines was developed. Chemoselective C(sp3)–H amidation of N-methyl group proceeded exclusively in the presence of C(sp2)–H bonds of the electron-rich aromatic ring. Site-selective C(sp3)–H amidation proceeded exclusively at the N-methyl group of N-methyl-N-alkylaniline derivatives with secondary, tertiary, and benzylic C(sp3)–H bonds α to a nitrogen atom.

Net charges and valence AO's in the methylamines; the hydrogen basis set and the properties of nitrogen

1985 ◽  
Vol 63 (7) ◽  
pp. 1487-1491 ◽  
Author(s):  
Giuseppe Del Re ◽  
Sándor Fliszár ◽  
Michel Comeau ◽  
Claude Mijoule
Keyword(s):  
Basis Set ◽  
Basis Sets ◽  
Methyl Groups ◽  
Extended Form ◽  
Amine Nitrogen ◽  
Methyl Group ◽  
Net Charges ◽  
Extended Basis

Net charges and valence AO's for ammonia, methylamine, dimethylamine, and trimethylamine were calculated using extended basis sets. Superposition effects, evaluated by replacing Pople's standard 6-31G* basis by an extended form in which the basis of the ammonia H atoms and of the methyl groups of trimethylamine are retained in the treatment of each molecule, indicate that the quality of the treatment of amine nitrogen atoms is strongly dependent on the number of methyl groups. A new, augmented basis is proposed for the hydrogens, which appears to be reasonably well balanced: comparison with familiar (e.g., 6-31G*) calculations illustrates in what manner the treatment of nitrogen is worsened when even just one methyl group is replaced by hydrogen unless the impoverishment of the basis is suitably taken care of.

scholarly journals Synthesis and spectral characterization of novel 1,5-benzodiazepine oxime derivatives

2019 ◽  
Vol 84 (4) ◽  
pp. 343-353
Author(s):  
Lina Rekovic ◽  
Lidija Kosychova ◽  
Irina Bratkovskaja ◽  
Regina Vidziunaite
Keyword(s):  
Nitrogen Atom ◽  
Fluorescence Spectroscopy ◽  
Organic Solvent ◽  
Elemental Analysis ◽  
13C Nmr ◽  
1H And 13C Nmr ◽  
Methyl Group ◽  
Oxime Derivatives ◽  
New Compounds

Three new 1,3,4,5-tetrahydro-2H-1,5-benzodiazepin-2-one oximes were synthesized and characterized by the methods of 1H- and 13C-NMR, IR and elemental analysis. Along with previously described compounds bearing one additional methyl group on the 5th nitrogen atom, the new compounds were characterized in bulk by UV?Vis and fluorescence spectroscopy in various solvents. The influence of the nature of the organic solvent on the spectra of the title compounds was investigated and is discussed.

The Rates and Products of Addition of 4-Chlorobenzenesulfenyl Chloride to a Series of Side Chain Methyl Substituted Styrenes

1974 ◽  
Vol 52 (9) ◽  
pp. 1807-1812 ◽  
Author(s):  
George H. Schmid ◽  
Dennis G. Garratt
Keyword(s):  
Steric Hindrance ◽  
Side Chain ◽  
Methyl Groups ◽  
Methyl Group

The rates of addition and the product compositions have been determined for the addition of 4-chlorobenzenesulfenyl chloride to a series of seven side chain methyl substituted styrenes in 1,1,2,2-tetrachloroethane at 25°. Unlike the addition to the corresponding series of methylated ethylenes, the effect of the methyl groups is not cumulative. The effect of the methyl groups depends upon whether or not the β-methyl group is cis to the phenyl. When it is cis, the rate of addition is decreased compared to styrene and substitution of additional methyl groups has only a small effect on the rate of addition. In compounds lacking a cis-β-methyl group the rate of addition more closely resembles that for addition to the methylated ethylenes. Steric hindrance between the cis-methyl and phenyl groups is believed to be the cause of this difference in behavior between the ethylene and styrene series.

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