Effect of Alkyl Group Structure on Cure Characteristics of N,N-Dialkylthio-Carbamyl-N′,N′-Dialkylsulfenamide Vulcanization Accelerators

1974 ◽  
Vol 47 (4) ◽  
pp. 906-910 ◽  
Author(s):  
R. D. Taylor
Keyword(s):  
Carbon Atom ◽  
Steric Hindrance ◽  
Alkyl Group ◽  
Group Structure ◽  
Substituent Effects ◽  
Steric Effects ◽  
Alkyl Groups ◽  
Inductive Effects ◽  
Cure Rates ◽  
Alpha Carbon

Abstract Wide variations in scorch times and cure rates can be attained with tetraalkylthiocabamylsulfenamides through variation in alkyl groups. Substituent effects are substantial on either the carbamate nitrogen or on the sulfenamide nitrogen. Both inductive effects and steric effects influence the scorch times and cure rates. Positive inductive effects shorten scorch times and increase cure rates. Steric hindrance at the sulfenamide nitrogen increases the scorch time. Branching at the carbon atom beta to the nitrogen has a larger effect on scorch time than branching at the alpha carbon. Thiocarbamylsulfenamides can give appreciably higher cure rates and cure efficiencies than their benzothiazole sulfenamide analogs.

Thermodynamics of metal-ligand bond formation. XIV. Adducts of hetercyclic bases with nickel(II) alkylxanthates

1974 ◽  
Vol 27 (10) ◽  
pp. 2099 ◽  
Author(s):  
DP Graddon ◽  
S Prakash
Keyword(s):  
Free Energy ◽  
Alkyl Group ◽  
Benzene Solution ◽  
Bond Formation ◽  
Adduct Formation ◽  
Steric Effects ◽  
Alkyl Chains ◽  
Inductive Effects ◽  
Metal Ligand ◽  
Ligand Bond

Thermodynamic data have been obtained for the formation in benzene solution of adducts of nickel(11) O-alkylxanthate complexes with one molecule of 2,2'-bipyridine or two molecules of pyridine or 4-methylpyridine. The results show that changes in the free energy and enthalpy of adduct formation with variation of the alkyl group in the xanthate can be explained wholly by inductive effects; there is no evidence for steric effects even with branched alkyl chains.

Correlation between Alkyl Cation Affinities and Proton Affinities—A Means to Rationalise Alkyl Group Substituent Effects

2000 ◽  
Vol 6 (2) ◽  
pp. 131-134 ◽  
Author(s):  
Einar Uggerud
Keyword(s):  
Linear Relationship ◽  
Alkyl Group ◽  
Substituent Effects ◽  
Alkyl Substituent ◽  
Thermochemical Data ◽  
Proton Affinities ◽  
Alkyl Groups ◽  
Substituent Constants ◽  
Straight Lines ◽  
Methyl Cation

Using literature thermochemical data it is demonstrated that the known linear relationship between proton affinities and methyl cation affinities can be extended to other alkyl groups (ethyl, i-propyl, t-butyl). It is suggested that the slopes of the straight lines can be used to define a new set of alkyl substituent constants.

The reaction of some nuclear substituted acyclic conjugated styryl ketones and related Mannich bases with ethanethiol

1980 ◽  
Vol 58 (10) ◽  
pp. 984-991 ◽  
Author(s):  
J. R. Dimmock ◽  
L. M. Smith ◽  
P. J. Smith
Keyword(s):  
Rate Constants ◽  
Alkyl Group ◽  
Mannich Bases ◽  
Second Order ◽  
Reaction Intermediates ◽  
Aqueous Acetonitrile ◽  
Alkyl Groups ◽  
Inductive Effects ◽  
The Stability ◽  
Carbonyl Function

The second order rate constants for the reaction of ethanethiol with a number of conjugated nuclear-substituted styryl ketones and related Mannich bases in 50% aqueous acetonitrile was undertaken. Variation of the alkyl group adjacent to the carbonyl function was accompanied by altered avidity to ethanethiol which was explained as being due in part to the varying inductive effects of the alkyl groups which would, in turn, affect the stability of the reaction intermediates. The greatest disparity in reactivity between groups of compounds was between the ketones and analogous Mannich bases which was in accord with the marked difference in bioactivities between these two groups of compounds.

scholarly journals The alkyl group is a -I + R substituent

2018 ◽  
Vol 28 (4) ◽  
Author(s):  
Luis Salvatella
Keyword(s):  
Alkyl Group ◽  
Dipole Moments ◽  
Substituent Effects ◽  
Uv Spectra ◽  
Substitution Effects ◽  
Resonance Effects ◽  
Alkyl Groups ◽  
Alkyl Substitution ◽  
Donor Substituent ◽  
Electron Donor Substituent

Electronic substituent effects are usually classified as inductive (through σ-bonds) and resonance effects (via π-bonds). The alkyl group has been usually regarded as aσ -electron donor substituent (+I effect, according to the Ingold’s classification). However, a σ-withdrawing, π-donor effect (-I + R pattern) allows explaining the actual electron-withdrawing behavior of alkyl groups when bound to sp³ carbon atoms as well as their well-known electron-releasing properties when attached to sp² or sp atoms. Alkyl substitution effects on several molecular properties (dipole moments, NMR, IR, and UV spectra, reactivity in gas phase and solution) are discussed.

Nickel-catalysed hydrogen exchange of alkylaromatic hydrocarbons and toluic acid derivatives with deuterium oxide

1965 ◽  
Vol 18 (7) ◽  
pp. 1009 ◽  
Author(s):  
CG Macdonald ◽  
JS Shannon
Keyword(s):  
Carbon Atom ◽  
Alkyl Group ◽  
Hydrogen Exchange ◽  
Deuterium Oxide ◽  
Dissociative Adsorption ◽  
Catalyst Poisoning ◽  
Benzylic Carbon ◽  
Alkyl Groups

The selective hydrogen exchange of alkyl groups of some alkylaromatic hydrocarbons and toluic acid derivatives was achieved by allowing these compounds to react with deuterium oxide over nickel on kieselguhr at 99�. The observed deuterium distributions and the results of catalyst poisoning experiments can be interpreted in terms of initial π-bonding of the substrates to the catalyst followed by dissociative adsorption at a benzylic carbon atom and transfer of adsorption through the alkyl group by an α-β process. Some nitro- and halo-toluenes underwent little or no exchange.

Substituent effects in the bis(benzotriazolylmethylation) of aromatic amines

1990 ◽  
Vol 68 (3) ◽  
pp. 446-455 ◽  
Author(s):  
Alan R. Katritzky ◽  
Stanislaw Rachwal ◽  
Jing Wu
Keyword(s):  
Steric Hindrance ◽  
Mannich Reaction ◽  
Aromatic Amines ◽  
Spectral Properties ◽  
Strong Influence ◽  
Substituent Effects ◽  
Equilibrium Mixture ◽  
Partial Separation ◽  
Alkyl Groups ◽  
The Stability

1-(Hydroxymethyl)benzotriazole and aromatic amines react to give an equilibrium mixture of N-mono- and N,N-bis(benzotriazolylmethyl)arylamines. Electron-releasing substituents on the arylamine ring shift the equilibrium towards the N,N-bis(benzotriazolylmethylated) products, and removal of water formed in the reaction leads to these bis derivatives in quantitative yields. These products were isolated as mixtures of three isomers, the benzotriazolyl-1,1′, -1,2′, and -2,2′ derivatives; these mixtures were characterized by full assignment of their 13CNMR spectra and by partial separation and enrichment. Electron-withdrawing substituents on the arylamine ring increase the isomer interconversion energy barriers and make N,N-bis(benzotriazolylmethyl)arylamines more resistant to hydrolysis. A strong influence of ortho alkyl groups on the stability and NMR spectral properties of N,N-bis(benzotriazolylmethyl)arylamines is interpreted on the basis of steric hindrance. Keywords: Mannich reaction, benzotriazole isomerization, substituent effects, anilines, bis(benzotriazolylmethyl)arylamines.

scholarly journals The substituent effects on the 13c chemical shifts of the azomethine carbon atom of n-(phenyl substituted) salycilaldimines

2012 ◽  
Vol 77 (8) ◽  
pp. 993-1001
Author(s):  
Sasa Drmanic ◽  
Aleksandar Marinkovic ◽  
Jasmina Nikolic ◽  
Bratislav Jovanovic
Keyword(s):  
Carbon Atom ◽  
Schiff Bases ◽  
13C Nmr ◽  
Chemical Shifts ◽  
Substituent Effects ◽  
13C Chemical Shifts ◽  
Resonance Effects ◽  
Inductive Effects ◽  
Substituent Constants ◽  
Significant Resonance

The Hammett correlations between 13C-NMR chemical shifts of the azomethine carbon atom and the corresponding substituent constants for thirtheen Schiff bases were established. Successful correlation of the chemical shifts with electrophilic substituent constants ?+ indicate significant resonance interaction of the substituents on the aniline ring with the azomethine carbon atom in the examined series of imines. The demand for electrons in the investigated compounds was compared to that of the N-benzylidenanilines and N-(phenyl substituted) pyridinealdimines. The way of transmission of the substituent effects was discussed and they are separated into resonance and inductive effects. Inductive effects prevail over resonance effects.

Nuclear magnetic resonance characterization of the ring conformations of monosubstituted derivatives of 1,3-dioxa-5,6-benzocycloheptene

1983 ◽  
Vol 61 (1) ◽  
pp. 109-115 ◽  
Author(s):  
R. St-Amour ◽  
M. St-Jacques
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Substituent Effects ◽  
Steric Effects ◽  
Slow Exchange ◽  
Conformational Properties ◽  
Derivatives Of ◽  
Ring Conformations ◽  
Twist Boat

The conformational properties of 2-alkyl (Me, Et, i-Pr, and t-Bu) and 2-phenyl derivatives of 1,3-dioxa-5,6-benzocycloheptene (1) were studied by 13C dnmr. Analysis of slow exchange spectra at 100.6 MHz indicates that all derivatives except tert-butyl exist in an equilibrium of chair (major) and twist-boat (minor) conformations. Substituent effects on the position of the equilibrium are rationalized in terms of steric effects.

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