STUDY OF RACEMIZATION IN ACID ANILIDES WITH DYNAMIC NMR AND SEMI-EMPERICAL MOLECULAR ORBITAL CALCULATIONS

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MILANI N.; DADGAR M.; TALEEI M.R.

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Paper Information

Journal: JOURNAL OF SCIENCES (ISLAMIC AZAD UNIVERSITY) Year:2005 | Volume:15 | Issue:56 Page(s): 154-173

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Title

STUDY OF RACEMIZATION IN ACID ANILIDES WITH DYNAMIC NMR AND SEMI-EMPERICAL MOLECULAR ORBITAL CALCULATIONS

Author(s)

MILANI N. | DADGAR M. | TALEEI M.R. | Issue Writer Certificate

Keywords

ACID ANILIDESQ4

DYNAMIC NMR. RACEMIZATIONQ4

CHEMICAL CALCULATIONSQ4

AML CALCULATIONSQ4

Abstract

ACID ANILIDES I are an important class of organic compounds. When R2#R3 ACID ANILIDES I are chiral and they have optical activity.Racemization in these compounds takes place by rotation about CAr-N bond. In room temperature rotation about this bond needs high energy barrier, therefore racemization don't occur. If compound I contain diastereotopic groups, For example R4=CH2C6H5, in 1HNMR spectra an AB quartet pattern is appeared. When temperature is increased the rotation about CAr-N bond becomes rapid on the NMR time scale, coalescence of the AB signal should be observed. The barrier to rotation about the CAr-N bond therefore can be obtained by the dynamic NMR technique. We study and measure of the energy barrier in the some derivatives of ACID ANILIDES I. We found that semiempirical SCFMO calculations can help to chemists for study of energy barrier in ACID ANILIDES I. Energy barrier for racemization of compound II (when X=H) via DNMR is 21 kcal mol-1. AM1 method calculate this barrier to 20.3 kcal mor-1. Electron withdrawing groups in the para-position (for example NO2 or Br) decrease the energy barrier of racemization for compound II (when X=NO2) this barrier is 18.9 kcal mor-1 and for compound II (when X=Br) this barrier is 20.6 kcal mol-1. The AMl method calculates these energy barriers 19.2 and 19.7 kcal mol-1 respectively. We report a study of transition state of racemization process that was calculated by AMl methods.

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APA: Copy

MILANI, N., DADGAR, M., & TALEEI, M.R.. (2005). STUDY OF RACEMIZATION IN ACID ANILIDES WITH DYNAMIC NMR AND SEMI-EMPERICAL MOLECULAR ORBITAL CALCULATIONS. JOURNAL OF SCIENCES (ISLAMIC AZAD UNIVERSITY), 15(56), 154-173. SID. https://sid.ir/paper/70399/en

Vancouver: Copy

MILANI N., DADGAR M., TALEEI M.R.. STUDY OF RACEMIZATION IN ACID ANILIDES WITH DYNAMIC NMR AND SEMI-EMPERICAL MOLECULAR ORBITAL CALCULATIONS. JOURNAL OF SCIENCES (ISLAMIC AZAD UNIVERSITY)[Internet]. 2005;15(56):154-173. Available from: https://sid.ir/paper/70399/en

IEEE: Copy

N. MILANI, M. DADGAR, and M.R. TALEEI, “STUDY OF RACEMIZATION IN ACID ANILIDES WITH DYNAMIC NMR AND SEMI-EMPERICAL MOLECULAR ORBITAL CALCULATIONS,” JOURNAL OF SCIENCES (ISLAMIC AZAD UNIVERSITY), vol. 15, no. 56, pp. 154–173, 2005, [Online]. Available: https://sid.ir/paper/70399/en

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