Sharif Digital Repository

In this research, the barrier around C-N bond in the molecule of 2-cyano ethyl morpholine-4-carbo dithioate was calculated by dynamic NMR. The 1H-NMR spectra of sample were recorded between temperatures of 240-332 K and 240-328 K in chloroform and acetone solvents, respectively. By analyzing the spectra by SpinWorks software, thermodynamic parameters (ΔG# , ΔH# , ΔS# ) extracded and compared with the data of quantum calculations . In quantum calculations, we compared data in two level (HF and B3LYP ).Consequently, the data of B3LYP method was better .Experimental ΔG# for internal rotation around C-N bond in 2-cyano ethyl morpholine-4-carbo dithioate was 14.04 kcal mol -1 and compared to... 

In this project rotational barrier around the C-N bond in 4-ethyle-morpholine- carboxylate has been studied using DNMR spectroscopy. Spectra were taken at variable temperature, and then with simulation of bandshape broadening pattern at coalescence region, rate constants of exchange were obtained for all temperatures. For simulation of line-shape broadening Spinworks software was used, that with two interfaces made possible simulation with two bandshape simulator programs, DNMR and MEXICO. The rate constants obtained from simulations, were used for calculation of thermodynamic activation parameters (∆G#, ∆H#, ∆S# and Ea). ∆G# 298 value of 13.66 Kcal/mol for 4-ethyle-morpholine- carboxylate... 

In this project rotational barrier around the C-N bond in Ethyl N-(pipyridin carbotioate) has been studied by using DNMR spectroscopy. Spectra were taken at various temperatures , and then with simulation of bandshape broadening pattern at coalescence region, the exchange rate constant of were obtained for all temperatures. For simulation of line-shpe broadening Spinworks software was used, that with two interfaces made possible simulation with two bandshape simulator programs, DNMR and MEXICO. The rate constants obtained from the simulation were used for calculation of thermodynamic activation parameters (... 

In this project rotational barrier of C-N bond in Ethyl N-(pyrrolidine carbotioate) has been studied using DNMR spectroscopy. Spectra were taken at various temperatures, and then with simulation of bandshape broadening pattern, rate constants of exchanges were obtained for all temperatures. For simulation of line-shape broadening SpinWorks software was used,which with two interfaces made possible simulation with two bandshape simulator programs, DNMR and MEXICO. The rate constants obtained from simulations, were used for calculation of thermodynamic activation parameters (?G#, ?H#, ?S# and Ea#).Experimental ?G# 298value(Experimental) of 18.3 Kcal/mol for Ethyl N-(pyrrolidine... 

In this work we have studied conformation of ranitidine by dynamic nuclear magnetic resonance spectroscopy (DNMR) in four different solvents: chloroform, acetone, dimethylsulfoxide, and deuteriumoxide. Ranitidine has three tatumeric forms of enamine, nitoic acid, and imine, but its stable structure is enamine. Temperature dependent 1HNMR spectra of ranitidine which reportet at 500MHz were consistent with the following free activation of energies ΔG# (kcal mol-1): chloroform = 16.2; acetone = 15.4; dimethylsulfoxide = 15.1. The experimental results were confirmed by DFT theoretical calculations at the B3LYP/6-311++G (d, p) level of theory. It was also proved that ranitidine has the form of... 

In this project the energy of rotational barrier of C-N bond in 2-cyanoethyl piperidine-1-carbodithioate has been studied by using Dynamic Nuclear Magnetic Resonance spectroscopy. Spectra were taken at various temperatures in two different solvent; acetone and chloroform. For simulation of line-shape broadening SpinWorks software was used. This with two interfaces made possible simulation with two band-shape simulator programs; DNMR and MEXICO. The rate constants obtained from simulations were used for calculation of thermodynamic activation parameters (ΔG#. ΔH#. ΔS# and Ea#). The computational calculations were done by using Gaussian03 in several level and basis sets that are in good... 

In this project, rotational barrier of C-N bond in thiobencarb (S-alkyl thiocarbamate) has been studied by HNMR spectroscopy. All the spectra were taken at different temperatures, and then by simulation of bandshape broadening pattern, rate constants for all temperatures were calculated. SpinWorks software was used for the simulation of line shape broadening which has two bandshape simulator programs, DNMR and MEXICO. The obtained rate constants were used to calculate the thermodynamic parameters of activation (ΔG‡, ΔH‡, ΔS‡ and Ea). Experimental ΔG‡298 value for thiobencarb was calculated 15.11kcalmol-1 and 15.86 kCalmol-1 in chloroform and acetone solvents respectively. The computational... 

In this project, 13 C nuclear magnetic shielding constants and also hindered internal rotation about C-N bond in compound 4 -(phenylacetyle) morpholine are investigated The Factorial Design method was used to obtain the best solution for chemical shift computations and comparison made out in two levels (HF and B 3 LYP). Consequently the (B 3 LYP) method own better data. 13 C NMR Spectra were taken at variable temperature ,and then with simulation of bandshape broadening pattern at coalescence region ,rate constants of exchange were obtained for all temperatures. For simulation of line-shape broadening Spinworks software was used, that with two interfaces made possible simulation with two... 

In this project, investigation of C-N internal rotation in ethyl tetrahydro-1(2H)-pyridine carbdithioate and ethyl 1-pyrrolidine carbodithioate were investigated by dynamic nuclear magnetic resonance spectroscopy. The 1HNMR and 13CNMR spectra were taken at the variable tempratures around the coalescence temprature. Thermodynamic parameters were calculated by analysing the spectra and the outcomes were compared by the theoretical results. For ethyl tetrahydro-1(2H)-pyridine carbdithioate ∆G‡ was 14.3 (kcal/mol) and for ethyl 1-pyrrolidine carbodithioate ∆G‡ was 17.0 (kcal/mol) which were in accordance with the theoretical results. The analysis were done by the Spinworks program which... 

The Barrier of the internal rotation around C-N bond in O-ethyle morpholine-4-carbotioate were calculated using dynamic NMR spectroscopy (DNMR) in DMSO solvent. 1H and 13C NMR spectra were recorded at different temperatures (295-350K). Band shape broadening patterns at coalescence regions were simulated to extract rate constants of NMR spectera. Transition state thermodynamic properties of internal rotation around C-N bond in O- ethyle morpholine -4- carbotioate are estimated: , , , . To assay reliability of the estimated values, transition state thermodynamic properties were calculated using PCM model at method and basis set B3LYP/6-311++G(d,p). Theoretical values of thermodynamic... 

In this project rotational barrier of C-N bond in 2-Cyanoethyl-Pyrrolidine-1-Carbodithioate has been studied using DNMR spectroscopy. Spectra were taken at various temperatures, and then with simulation of bandshape broadening pattern, rate constants of exchanges were obtained for all temperatures. For simulation of line-shape broadening SpinWorks software was used,which with two interfaces made possible simulation with two bandshape simulator programs, DNMR and MEXICO. The rate constants obtained from simulations, were used for calculation of thermodynamic activation parameters (ΔG#, ΔH#, ΔS# and Ea#). Experimental ΔG# value of 18.4 Kcal mol-1 for 2-Cyanoethyl-Pyrrolidine-1-Carboditioate in...