Molbank 2004, M360

http://www.mdpi.net/molbank/

　

1,3-Diethyl-5-(4-methoxybenzylidene)-2-thioxodihydropyrimidine-4,6(1H,5H)-dione

  

Abdullah Mohamed Asiria*, Khaled Ahmed Alamry a Abraham F. Jalbout b,c and S Zhang b

　

a Chemistry Department, Faculty of Science, King Abdul-Aziz University,

Jeddah 21413, P.O. Box 9028, Saudi Arabia. Tel.+966-2-6952293, Fax +966-2-6952293, E-mail: [email protected]  

b  Department of Physics, Dillard University, New Orleans, LA 70112, USA

cEJMAPS Organization, 1107 Carrolton Ave., Metairie, LA 70005, USA

 

Received: 13 September 2003 / Accepted:  4 February 2004 / Published: 24 February 2004

　

 

1,3-Diethyl-5-(4-methoxybenzylidene)-2-thioxodihydropyrimidine-4,6(1H,5H)-dione 3 was prepared by Knoevenagel condensation of 4-methoxybenzaldehyde 1 and N,N-diethylthiobarbituric acid 2 in ethanol using piperidine as a base [1,2].

            N,N-Diethylthiobarbituric acid 2 ( 7.5 g, 0.0375 mol)  and

4-methoxybenzaldehyde 1 (5.1 g, 0.0375 mmol ) in ethanol (75 mL) were heated under reflux for five minutes. Piperidine (1.0 mL) was added in one portion and the reflux was continued for five hours. The reaction mixture was cooled to room temperature and the solid formed was filtered, washed with cold ethanol (2x 40 mL) and dried. 1,3-Diethyl-5-(4-methoxybenzylidene)-2-thioxodihydropyrimidine-4,6(1H,5H)-dione 3 was  recrystallized from ethanol as yellow crystals (10.86g, 91%). 

　

　

　

M.p. 147 ºC  ( uncorrected.).

　

UV lmax (nm; CHCl3)/e (dm3.mol-1.cm-1) 414/25000 and 258/ 5848.

　

IR (KBr) cm-1 2978, 1661 (C=O), 1602 (C=C), 1433.5, 1387 (CS).

Theoretical (cm-1; AM1): 1650.6; 1462.1; 1388.8

 

1H-NMR (400 MHz; CDCL3; Me4Si) dH 8.52 (1H, s, -CH=C), 8.37 (2H, d, J = 8.94 Hz, aromatic), 7.00(2H, d, J = 7.24 Hz, J = 8.94 Hz, aromatic), 4.58 ( 4H, t, 2xCH2), 3,90 (3H, s, MeO), 1.32 ( 6H, q, CH3).

 

13C-NMR (100 MHz; CDCL3; Me4Si)  dC 174.9 (C=S), 163.8, 163.4 (C=O), 157.7, 137.7 (CH oliefinc), 155.6, 132.4, 128.2, 126.5 (C), 114.5, 56.03 (MeO), 44.6, 44.3 (CH2), 13.5, 13.2 (CH3).

　

Anal.Calc. for C16H18N2O3S ( 318.392): C 60.36, H 5.70 , N 10.07; found : C 60.15, H 5.5.79, N 10.20.

 

Theoretical calculations were performed with the GAUSSIAN 98 package [3] using the AM1 semi-empirical model [4]. From the above (AM1 values) we see that the theoretical and experimental values are in good agreement. Using a rigid-rotor/harmonic-oscillator (RRHO) approximation in agreement with NIST standards we compute at 298.15 K, S (entropy in J mol-1 K-1) as 674.66, Cp as 329.70 (heat capacity at constant pressure in kJ mol-1 K-1) and H＜ - H＜298.15 as 58.50 (enthalpy content, in kJ mol-1). The equations most useful for indexing these species with the NIST are:

　

 

Fitted Thermodynamic Equation (T/1000=t)

T1

T2

T3

S

-7.63127*ln(t) + 1284.11508*t -578.09841*t2/2 + 33.99402*t3/3 + 0.57583/(2*t2) +311.06252

425.38         

674.66         

1317.25       

Cp

329.41584+ 1243.04945*t -253.18884*t2

-1.8789*t3 -0.25805*t-2

157.48         

329.70         

 738.27         

DH

148.67084*t + 5284.44948*t2/2 -9023.3457*t3/3 + 4547.86803*t4/4 + 16.23129

10.27

58.50

460.39

 

References

　

1. G. Jones, Org. React., 1967, 15, 204.

2. K. Tanaka, X. Chen and F. Yoneda, Tetrahedron, 1988, 44, 3241.

3. M. J. Frisch, et. al. , Gaussian 98,Revision A.6, Gaussian, Inc., Pittsburgh PA, 1998.

4. J.B. Foresman, Æ Frisch, Exploring Chemistry with Electronic Structure Methods, 2nd edition Gaussian, INC, Pittsburgh, PA, 1996.

5. P.J. Linstrom, W.G.  Mallard, Eds., NIST Chemistry WebBook, NIST Standard Reference Database Number 69, July 2001, National Institute of Standards and Technology, Gaithersburg MD, 20899 (http://webbook.nist.gov).

 

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