17O NMR study of ortho and alkyl substituent effects in substituted phenyl and alkyl esters of benzoic acids

2011 ◽  
Vol 76 (12) ◽  
pp. 1737-1763 ◽  
Author(s):  
Vilve Nummert ◽  
Vahur Mäemets ◽  
Mare Piirsalu ◽  
Signe Vahur ◽  
Ilmar A. Koppel
Keyword(s):  
Chemical Shifts ◽  
Substituent Effects ◽  
Alkyl Substituent ◽  
Ester Group ◽  
Carbonyl Oxygen ◽  
Steric Interaction ◽  
Alkyl Esters ◽  
17O Nmr ◽  
Nmr Study ◽  
Substituent Constants

17O NMR spectra for 44 ortho-, meta- and para-substituted phenyl and alkyl benzoates (C6H5CO2C6H4-X, C6H5CO2R) at natural abundance in acetonitrile were recorded. Substituent effects on the 17O NMR chemical shifts, δ(17O), of the carbonyl oxygen and the single-bonded phenoxy (OPh) and alkoxy (OR) oxygens have been studied. The δ(17O) values of the carbonyl oxygen for para derivatives showed a good correlation with the σ° constants. The δ(17O) values of carbonyl oxygen for ortho derivatives were found to be described well with the Charton equation containing the inductive, σI, resonance, σ°R, and steric, EsB, substituent constants in case the data treatment was performed separately for electron-donating +R and electron-attracting –R substituents. The electron-donating +R ortho and para substituents in substituted benzoates caused shielding and the electron-withdrawing –R substituents produced deshielding of the O signal. The steric interaction of ortho substituents with the ester group decreased the electron density at the carbonyl oxygen. In alkyl benzoates the δ(17O) values were found to be described well with the inductive, σI, and the steric, EsB, substituent constants.

Kinetic Study of Hydrolysis of Benzoates. Part XXVI. Variation of the Substituent Effect with Solvent in Alkaline Hydrolysis of Substituted Alkyl Benzoates

2006 ◽  
Vol 71 (11-12) ◽  
pp. 1557-1570 ◽  
Author(s):  
Vilve Nummert ◽  
Mare Piirsalu ◽  
Ilmar A. Koppel
Keyword(s):  
Kinetic Study ◽  
Alkaline Hydrolysis ◽  
Rate Constants ◽  
Substituent Effect ◽  
Substituent Effects ◽  
Alkyl Substituent ◽  
Solvent Parameters ◽  
Substituent Constants ◽  
Hydrolysis Of ◽  
Main Factor

The second-order rate constants k2 (dm3 mol-1 s-1) for the alkaline hydrolysis of substituted alkyl benzoates C6H5CO2R have been measured spectrophotometrically in aqueous 0.5 M Bu4NBr at 50 and 25 °C (R = CH3, CH2Cl, CH2CN, CH2C≡CH, CH2C6H5, CH2CH2Cl, CH2CH2OCH3, CH2CH3) and in aqueous 5.3 M NaClO4 at 25 °C (R = CH3, CH2Cl, CH2CN, CH2C≡CH). The dependence of the alkyl substituent effects on different solvent parameters was studied using the following equations:      ∆ log k = c0 + c1σI + c2EsB + c3∆E + c4∆Y + c5∆P + c6∆EσI + c7∆YσI + c8∆PσI     ∆ log k = c0 + c1σ* + c2EsB + c3∆E + c4∆Y + c5∆P + c6∆Eσ* + c7∆Yσ* + c8∆Pσ* .  ∆ log k = log kR - log kCH3. σI and σ* are the Taft inductive and polar substituent constants. E, Y and P are the solvent electrophilicity, polarity and polarizability parameters, respectively. In the data treatment ∆E = ES - EH2O , ∆Y = YS - YH2O , ∆P = PS - PH2O were used. The solvent electrophilicity, E, was found to be the main factor responsible for changes in alkyl substituent effects with medium. When σI constants were used, variation of the polar term of alkyl substituents with the solvent electrophilicity E was found to be similar to that observed earlier for meta and para substituents, but twice less when σ* constants were used. The steric term for alkyl substituents was approximately independent of the solvent parameters.

scholarly journals Correlation analysis of IR, 1H and 13C NMR spectral data of N-alkyl and N-cycloalkyl cyanoacetamides

2011 ◽  
Vol 17 (3) ◽  
pp. 307-314 ◽  
Author(s):  
Aleksandar Marinkovic ◽  
Jelena Nedeljkovic ◽  
Dusan Mijin ◽  
Natasa Ilic ◽  
Slobodan Petrovic
Keyword(s):  
Spectral Data ◽  
13C Nmr ◽  
Ethyl Cyanoacetate ◽  
Substituent Effects ◽  
Alkyl Substituent ◽  
Steric Interaction ◽  
1H And 13C Nmr ◽  
Linear Free Energy ◽  
Energy Relationships ◽  
Reverse Substituent Effect

Linear free energy relationships (LFER) were applied to the IR, 1H and 13C NMR spectral data in Nalkyl and N-cycloalkyl cyanoacetamides. N-alkyl and N-cycloalkyl cyanocetamides were synthesized from corresponding amine and ethyl cyanoacetate. A number of substituents were employed for alkyl substitution, and fairly good correlations were obtained, using simple Hammett equation. In N-alkyl and N-cycloalkyl cyanoacetamides substituent cause SCS of N-H hydrogen primarily by steric interaction, polar subtituent effect influences SCS shift of C=O carbon, while steric effect of N-alkyl substituent causes IR stretching frequencies of N-H, C=O and CN group. The conformations of investigated compounds have been studied by the use of semiempirical PM6 method, and together with LFER analysis, give a better insight into the influence of such a structure on the transmission of electronic substituent effects. Negative ? values for several correlations (reverse substituent effect) were found.

Multinuclear (1H, 13C and 15N) Magnetic Resonance Spectroscopy and Substituent Effects on N-Phenoxyethylanilines

2002 ◽  
Vol 57 (2) ◽  
pp. 226-232 ◽  
Author(s):  
Jorge L. Jios ◽  
Gustavo P. Romanelli ◽  
Juan C. Autino ◽  
Damian Magiera ◽  
Helmut Duddeck
Keyword(s):  
Magnetic Resonance ◽  
Magnetic Resonance Spectroscopy ◽  
Substituent Effect ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Substituent Effects ◽  
The Other ◽  
Resonance Spectroscopy ◽  
Phenyl Rings ◽  
Substituent Constants

1H, 13C and 15N NMR spectra of twenty substituted N-phenoxyethylanilines 1-20 were completely and unambiguously assigned using a combination of both homo- and heteronuclear (gs-COSY), 1H detected heteronuclear one-bond (gs-HMQC) and long-range (gs- HMBC) gradient-selected correlation experiments. Correlations between chemical shifts and substituent constants are analyzed separately for both phenyl rings using variable substituents para to the fixed substituent -OCH2CH2NHC6H5 (series I) and -NHCH2CH2OC6H5 (series II), respectively. The correlation coefficient for chemical shifts vs. a linear combination of inductive and resonance substituent constants is high and improves when only the six values, corresponding to each para-monosubstituted series, were used. For nitrogen chemical shifts excellent linear dependences were obtained. The results show that the ethylene chain is not able to transmit the substituent effect from one aromatic ring to the other.

Torsional angles in N-substituted benzamides and related compounds by carbon-13 N.M.R. chemical shifts

1981 ◽  
Vol 34 (5) ◽  
pp. 957 ◽  
Author(s):  
CW Fong ◽  
HG Grant
Keyword(s):  
Steric Effect ◽  
Chemical Shifts ◽  
Steric Interaction ◽  
Hydrogen Atoms ◽  
Ring Inversion ◽  
Nitrogen Inversion ◽  
Substituted Benzamides ◽  
Substituent Constants ◽  
Torsional Angles ◽  
Related Compounds

The torsional angles in 30 N-substituted benzamides and related compounds have been estimated by the use of the 13C substituent chemical shifts of the meta and para carbon atoms. Steric interaction between the N-substituted groups and the ortho hydrogen atoms of the benzene ring is the major determinant of non-planarity in these systems. A linear relationship between steric substituent constants of the N-substituted groups of some benzamides and the torsional angles is proposed. Dynamic processes involving rotation about the C-N bond, nitrogen inversion and ring inversion contribute a dynamic steric effect to the overall steric interaction. The preferred conformations of some N-substituted groups is also discussed.

ChemInform Abstract: Substituent Effects on 15N and 17O NMR Chemical Shifts in 4′-Substituted trans-NNO-Azoxybenzenes

ChemInform ◽  
1990 ◽  
Vol 21 (27) ◽  
Author(s):  
M. SAWADA ◽  
Y. TAKAI ◽  
T. TANAKA ◽  
T. HANAFUSA ◽  
M. OKUBO ◽  
...  
Keyword(s):  
Chemical Shifts ◽  
Substituent Effects ◽  
17O Nmr ◽  
Nmr Chemical Shifts

scholarly journals Solvent-Free Synthesis and Assessment of Substituent Effects from IR & NMR Spectra of some Substituted Benzylidene-5-Ethyl-1,3,4-Thiadiazole-2-Amines

2013 ◽  
Vol 24 ◽  
pp. 89-98
Author(s):  
Ganesamoorthy Thirunarayanan
Keyword(s):  
Spectroscopic Data ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Linear Regression Analysis ◽  
Substituent Effects ◽  
Solvent Free ◽  
Substituent Constants ◽  
Multi Linear Regression ◽  
Solvent Free Synthesis ◽  
Spectral Group

A series containing ten titled compounds were synthesized by SiO2:H3PO4 catalyzed solvent-free condensation of substituted benzaldehydes and 2-amino-5-ethyl-1,3,4-thiadiazole under microwave irradiation. The yields of prepared amines are more than 90%. The synthesized amines were characterized by their physical constants and spectroscopic data reported in literature earlier for known compounds. The assigned spectral group frequencies such as infrared νC=N, C-S-C, N-N (cm-1) and NMR chemical shifts (δ, ppm) of CH, C=N have been correlated with Hammett substituent constants, F and R parameters using single and multi-linear regression analysis. From the results of statistical analyses, the effects of substituent on the above spectral data have been discussed.

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.

Chemometrical analysis of substituent effects on 13C and 15N NMR chemical shifts in 1-aroyl-3-substituted thioureas

1989 ◽  
Vol 54 (9) ◽  
pp. 2399-2407 ◽  
Author(s):  
Oldřich Pytela ◽  
Josef Jirman ◽  
Antonín Lyčka
Keyword(s):  
Latent Variables ◽  
Chemical Shifts ◽  
Substituent Effects ◽  
The Other ◽  
15N Nmr ◽  
Nmr Chemical Shifts ◽  
Additional Constant ◽  
Substituent Constants ◽  
Derivatives Of ◽  
C Nmr

The methods of conjugated deviations and regression analysis have been used to study the substituent effects on 13C and 15N NMR chemical shifts of 12 derivatives of 1-aroyl-3-phenylthiourea and 1-aroyl-3-methylthiourea. The 13C NMR chemical shifts can be described by two latent variables, one univocally correlated with the Hammett substituent constants (r = 0.993) and the other reflecting the increased shielding of the nuclei due to overlap of the adjacent bond electrons as a consequence of electron-donor or electron-acceptor character of the substituents.This effect is less pronounced with the 15N nuclei. Application of dual substituent constants σR, σF with the additional constant σα describing the polarization has failed in giving sufficiently close correlations and explanation of the substituent effect found.

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