scholarly journals Synthesis and investigation of solvent effects on the ultraviolet absorption spectra of 5-substituted-4-methyl-3-cyano-6-hydroxy-2-pyridones

2001 ◽  
Vol 66 (8) ◽  
pp. 507-516 ◽  
Author(s):  
Dusan Mijin ◽  
Gordana Uscumlic ◽  
Natasa Valentic
Keyword(s):  
Hydrogen Bond ◽  
Absorption Spectra ◽  
Ethyl Acetoacetate ◽  
Solvent Polarity ◽  
Ultraviolet Absorption ◽  
Hydrogen Bond Donor ◽  
Reaction Conditions ◽  
Hydrogen Bond Acceptor ◽  
Energy Relationships ◽  
Linear Solvation Energy

A number of 5-substituted-4-methyl-3-cyano-6-hydroxy-2-pyridones from cyanoacetamide and the corresponding alkyl ethyl acetoacetates were synthesized according to modified literature procedures. The alkyl ethyl acetoacetates were obtained by the reaction of C-alkylation of ethyl acetoacetate. An investigation of the reaction conditions for the synthesis of 4-methyl-3-cyano-6-hydroxy-2-pyridone from cyanoacetamide and ethyl acetoacetate in eight different solvents was also performed. The ultraviolet absorption spectra of synthesized pyridones were measured in nine different solvents in the range 200-400 nm. The effects of solvent polarity and hydrogen bonding on the absorption spectra are interpreted by means of linear solvation energy relationships using a general equation of the form v = vo + s?*+a?+b?, where ?* is a measure of the solvent polarity, ? is the scale of the solvent hydrogen bond donor acidities and ? is the scale of the solvent hydrogen bond acceptor basicities.

scholarly journals Synthesis and investigation of solvent effects on the ultraviolet absorption spectra of 1, 3-bis-substituted-5, 5-dimethylhydantoins

2003 ◽  
Vol 68 (10) ◽  
pp. 699-706 ◽  
Author(s):  
Gordana Uscumlic ◽  
Abdulbaseta Kshad ◽  
Dusan Mijin
Keyword(s):  
Hydrogen Bond ◽  
Absorption Spectra ◽  
Electronic Absorption Spectra ◽  
Alkyl Halide ◽  
Substituent Effects ◽  
Solvent Polarity ◽  
Hydrogen Bond Donor ◽  
Hydrogen Bond Acceptor ◽  
Isolation Techniques ◽  
Energy Relationships

A series of 1,3-bis-substituted-5,5-dimethylhydantoins was synthesized using the reaction of 5,5-dimethylhydantoin with the corresponding alkyl halide in the presence of trimethylamine as catalyst and sodium hydroxide, according to a modified literature procedure. The experimental investigation included modification of the synthetic procedure in terms of starting materials solvent, temperature, isolation techniques, as well as purification and identification of the products. The absorption spectra of the 1,3-bis-substituted-5,5-dimethylhydantoins were recorded in twelve solvents in the range 200?400 nm. The effects of the solvent polarity and hydrogen bonding on the absorption spectra were interpreted by means of linear solvation energy relationships using a general equation of the form ? = ?0 s?* + a? + b? and by two-parameter models presented by the equation ? = ?0 s?* + a?, where ?* is a measure of the solvent polarity/polarisability, ? is the scale of the solvent hydrogen bond donor acidities and ? is the scale of the solvent hydrogen bond acceptor basicities. The solvent and substituent effects on the electronic absorption spectra of the investigated hydantoins is discussed.

scholarly journals Solvent effect on electronic absorption spectra of cyclohex-1-enylcarboxylic and 2-methylcyclohex-1-enylcarboxylic acids

2000 ◽  
Vol 65 (5-6) ◽  
pp. 353-359 ◽  
Author(s):  
Jasmina Nikolic ◽  
Gordana Uscumlic ◽  
Vera Krstic
Keyword(s):  
Hydrogen Bond ◽  
Absorption Spectra ◽  
Electronic Absorption Spectra ◽  
Linear Regression Analysis ◽  
Solvent Polarity ◽  
Multiple Linear Regression Analysis ◽  
Ultraviolet Absorption ◽  
Aprotic Solvents ◽  
Hydrogen Bond Donor ◽  
Hydrogen Bond Acceptor

The ultraviolet absorption spectra of cyclohex-1-enylcarboxylic acid and 2- methylcyclohex-1-enylcarboxylic acid were determined in six protic and nine aprotic solvents in the wavelength range from 200 to 400 nm. The position of the ?max of the two examined acids showed that the ultraviolet absorption maximums of cyclohex-1-enylcarboxylic acid were at consistently longer wavelengths in protic solvents than those of methylcyclohex-1-enylcarboxylic acid. The opposite was true in aprotic solvents. In order to explain the obtained results, the ultraviolet absorption frequencies of the electronic transitions in the carboxy carbonyl group of the examined acids were correlated using a total solvatochromic equation of the form: v = v0 + s?* + a? + b?, where ?* is a measure of the solvent polarity, ? represents the scale of solvent hydrogen bond acceptor basicities and a represents the scale of solvent hydrogen bond donor acidities. The correlation of the spectroscopic data was carried out by means of multiple linear regression analysis. The opposing solvent effects on the ultraviolet absorption maximums of the two examined acids were discussed.

scholarly journals The influence of the solvent on organic reactivity. Part II. Hydroxylic solvent effects on the reaction rates of diazodiphenylmethane with 2-(2-substituted cyclohex-1-enyl)acetic and 2-(2-substituted

2004 ◽  
Vol 69 (8-9) ◽  
pp. 601-610 ◽  
Author(s):  
Jasmina Nikolic ◽  
Gordana Uscumlic ◽  
Vera Krstic
Keyword(s):  
Hydrogen Bond ◽  
Solvent Effects ◽  
Linear Regression Analysis ◽  
Solvent Polarity ◽  
Multiple Linear Regression Analysis ◽  
Reaction Rates ◽  
Hydrogen Bond Donor ◽  
Initial State ◽  
Hydrogen Bond Acceptor ◽  
Acetic Acids

The rate constants for the reaction of diazodiphenylmethane with 2-(2-substituted cyclohex-1-enyl)acetic acids and 2-(2-substituted phenyl)acetic acids, previously determined in seven hydroxylic solvents, were correlated using the total solvatochromic equation, of the form logk = logk0 + s?*+ a? + b?, the two-parameter model, logk=logk0 + s?*+ a? and a single parameter model logk = logk0 + b?, where ?*is a measure of the solvent polarity, ? represents the scale of solvent hydrogen bond acceptor basicities and ? represents the scale of solvent hydrogen bond donor acidities. The correlations of the kinetic data were carried out by means of multiple linear regression analysis and the solvent effects on the reaction rates were analyzed in terms of initial state and transition state contributions.

scholarly journals The reactivity of α,β-unsaturated carboxylic acids. Part XVI. The kinetics of the reaction of cycloalkenecarboxylic and cycloalkenylacetic acids with diazodiphenylmethane in various alcohols

2002 ◽  
Vol 67 (2) ◽  
pp. 77-85 ◽  
Author(s):  
Gordana Uscumlic ◽  
Jasmina Nikolic ◽  
Vera Krstic
Keyword(s):  
Hydrogen Bond ◽  
Rate Constants ◽  
Kinetic Data ◽  
Linear Regression Analysis ◽  
Spectroscopic Method ◽  
Solvent Polarity ◽  
Multiple Linear Regression Analysis ◽  
Hydrogen Bond Donor ◽  
Experimental Conditions ◽  
Hydrogen Bond Acceptor

The rate constants for the reaction of diazodiphenylmethane with 1-cyclopentenecarboxylic, 1-cycloheptenecarboxylic, cyclopent-1-enylacetic and cyclohept-1-enylacetic acids were determined in eight alcohols at 30 ?C using the appropriate UV-spectroscopic method. In order to explain the kinetic results through solvent effects, the second order rate constants of the examined acids were correlated using a total solvatochromic equation, of the form: log k = A0+ s?*+a??+ b?, where ?* is a measure of the solvent polarity, ??represents the scale of solvent hydrogen bond acceptor basicities and ? represents the scale of solvent hydrogen bond donor acidities. The correlations of the kinetic data were carried out by means of multiple linear regression analysis. The opposite sings of the electrophilic and the nucleophilic parameters are in agreement with the well-known reaction mechanism. The results presented in this paper were compared with the kinetic data for 1-cyclohexenecarboxylic and cyclohex-1-enylacetic acids obtained under the same experimental conditions.

scholarly journals The kinetics of the reactions of 2-substituted nicotinic acids with diazodiphenylmethane in various alcohols

2003 ◽  
Vol 68 (7) ◽  
pp. 515-524 ◽  
Author(s):  
Sasa Drmanic ◽  
Bratislav Jovanovic ◽  
Aleksandar Marinkovic ◽  
Milica Misic-Vukovic
Keyword(s):  
Hydrogen Bond ◽  
Rate Constants ◽  
Linear Regression Analysis ◽  
Solvent Polarity ◽  
Multiple Linear Regression Analysis ◽  
Hydrogen Bond Donor ◽  
Initial State ◽  
Experimental Conditions ◽  
Hydrogen Bond Acceptor ◽  
Reaction Rate Constants

The rate constants of 2-substituted nicotinic acids in reaction with diazodiphenylmethane (DDM) in eight alcohols at 30 ?C have been determined. In order to explain the obtained results through solvent effects, the second order reaction rate constants (k) of the examined acids were correlated using the appropriate solvent parameters by the equation: logk=logk0 af(?) + b?* + cn?H where f(?) is the measure of solvent ability as a dielectric to stabilize the separation of opposite charges in the activated complex, ?* is the measure of solvent ability to stabilize proton in the initial state and n?H represents the ability of protic solvents to form hydrogen bond with the negative end of the ion-pair intermediate. These constants were correlated also by using solvatochromic equation of the form logk=logk0 + s?* + a? + b? where ?* is the measure of the solvent polarity, ? represents the scale of the solvent hydrogen bond donor acidities (HBD) and ? represents the scale of the solvent hydrogen bond acceptor basicities (HBA). The correlations of the kinetic data were carried out by means of multiple linear regression analysis. The results obtained for 2-substituted nicotinic acids were compared with the results for ortho-substituted benzoic acid under the same experimental conditions.

Resonance and solvent effects on absorption spectra of some 2- and 4-( - M)-substituted aniline derivatives

1983 ◽  
Vol 36 (4) ◽  
pp. 701 ◽  
Author(s):  
T Yokoyama ◽  
RW Taft ◽  
MJ Kamlet
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Spectral Data ◽  
Absorption Spectra ◽  
Solvent Effects ◽  
Hydrogen Bond Donor ◽  
Intermolecular Hydrogen Bonds ◽  
Hydrogen Bond Acceptor ◽  
Aniline Derivatives ◽  
Hydrogen Bonded

The N-H protons of N-methyl-2-X-aniline derivatives remain intramolecularly hydrogen bonded in HBA (hydrogen bond acceptor) solvents where X = COOMe and NO2, but form intermolecular hydrogen bonds to the HBA solvents where X = CN. The order of response of vmax to solvent HBA basicity for the Cl → C2 bands of N-unsubstituted-2-(-M)-substituted aniline derivatives and the Cl → C4 bands of 4-(-M)-substituted aniline derivatives follows the orders of the hydrogen bond donor acidities of the amine protons, which are determined primarily by the mesomeric effects of the 2- and 4-substituents. The spectral data indicate that intramolecularly hydrogen bonded 2-(-M)-substituted aniline derivatives are near sp2 hybridized in non-HBA solvents and, unlike several 4-substitute anilines, do not undergo significant rehybridization in HBA solvents. Bath ochromic shifts resulting from hydrogen bonds by corresponding 2- and 4-substituted aniline derivatives to HBA solvents are of similar magnitudes.

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