17 min R A (2009) To probe into the thermal property the mechanism of the thermal decomposition and the prospective

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1 ( 31001) (CDZ)CDZCDZ GAMSSCDZCDZ (DSC)CDZCDZ (G) DakinCDZ 1 1 CDZ a =173.9 kj mol min -1 CDZ 17 min A= A= R97.14A (009) a =17.3 kj mol 1 Mechanism and Kinetics of hermal Decomposition of Cefodizime Disodium WANG Xuejie, YOU Jinzong(School of Science and echnology, Zhejiang ducation Institute, Hangzhou 31001, China) ABSRAC: OBJCIV el: Chin o probe into the thermal propertythe mechanism of the thermal decomposition and the prospective (0571) mail: xjwang@zjei.net JMAP, 009 December, Vol.6 No

2 lifetime of cefodizime disodium (CDZ). MHODS he thermal decomposition of CDZ was measured by thermogravimetry (G) and differential scanning calorimetry(dsc)the IR spectra of CDZ and its remainders from thermal decomposition at various temperatures were determined, the molecular bond orders were calculated by GAMSS method of quantum chemistry, the kinetics parameters of thermal decomposition of SVD were obtained by thermogravimetry and the prospective lifetime of CDZ at different temperature was speculated by Dakin equation. RSULS he results indicated that the thermal decomposition of CDZ was a multi-stages process. he kinetic parameters, such as activation energy a =173.9 kj mol -1, pre-exponential factor A = min -1 in N, and a =17.3 kj mol -1, A = min -1 in airwere obtained. CONCLUSION he thermal property of CDZ is quite stable in the routine temperature. KY WORDS: cefodizime disodium; quantum chemistry; thermoanalysis; mechanism; thermogravimetry; differential scanning calorimetry [1-4] CDZ)HoestRusell (cefodizime disodium [5] (DSC)CDZ (G) GAMSSCDZCDZ CDZ CDZ )(A)CDZ ( a 1 CDZ( ) (A) 1SD-Q Chin JMAP, 009 December, Vol.6 No F/IR-460 ( Jasco)KBr 1 CDZ Fig 1 he molecular structure mg of CDZ 1. (15±0.5) 1 ) (100 ml min min DGDSC G 40~1 000 CDZA ChemDraw HF/3-1G* ChemOfficeChemDrawCDZ GAMSSHartree-Fock CDZ 1.1 G/DGCDZ CDZ10 GDG CDZ 0 CDZ G 100 min

3 DG59 1.5%CDZ CDZG G 500 DG O %Na 18.%DG 50.4% 30 DG617 CDZ850 17% Na 19.8%)14.1% 4 Na CO 314.8%Na SO DG %Na CO Na SO 4GNa 30% 5% Na SO Chin SO 4Na CO 3 ( CO O Na CDZ10 min 1G/DG 1 1 Fig G/DG curves of CDZ, heating rate: 10 min CDZ10 min G/DSC300 DSC CDZDSCG DSC G DGDSC CDZ DSC 500 DG DSCCDZ DSC Na CO Na SO Na SO 4Na CO 3 CDZ10 min 1G/DSC 1 Fig 3 G/DSC curves of CDZ, heating rate: 10 min DG β maxcdz max11 max1β 1 DG ab 1 he relationship between heating rate β and peak temp. max1 of DG = β β max 1 = β β max 1 CDZ. CDZ 4CDZ JMAP, 009 December, Vol.6 No.1 101

4 CDZ CDZCDZO 34 -C 37 N 13CDZ 1 C 1 -C C 1 -C DSC O Na SO 4Na CO 3Na -C N 1 -C 1C -C Chin JMAP, 009 December, Vol.6 No CDZ 4 CDZ Fig 4 he molecular bond orders of 5 CDZ cm 5 CDZ 330 IR; 1CDZIR; 10 IR; 4450 IR; IR 5700 Fig 5 IR Spectra of CDZ and remainders in thermal decomposition 1IR Spectrum of CDZ; IR Spectrum of remainder at 10 ; 3IR Spectrum of remainder at 30 ; 4IR Spectrum of remainder at 450 ; 5IR Spectrum of remainder at cm cm 1SCN Na Na CO cm 1875 cm 3 Na SO 4Na CO CDZ CDZ.3 A A a k 1A k t 1K 1 min 1 J mol a R8.314 J K 1 mol β cm 1 C-O-C SO cm 160 cm 1 ASM [6] (model-free method) Arrhenius k = A exp(- a /R) (1) Ozawa [7]Flynn J H[8] = lg β ( a /R) () α 1β 1β β lg β ( a /R 1 ) = lg β ( a /R ) = lg β ( a /R 1 3 ) (3) αlg β a ( /R) a A β (3)(4)CDZ a A = β( a /R)exp( a /R) (4) ACDZ a α α 3α 4

5 CDZ α % kj mol CDZ [9] Dakin τ τ CDZ a 3 CDZ5.5%(18%) lg = a + a= a /.303RbnA 3 ab 3 CDZ / C /min 1 /h /min 1 /h he prospective lifetime of CDZ at different temperature a /kj mol 1 /Log[A min 1 ] b (GAMSS)CDZCDZ CDZ CDZ 1 a =173.9 kj mol CDZ 1CDZ min A= RFRNCS 1 1 A= min a =17.3 kj mol [1] AO Y ZHAN DZHANG K L. Kinetics of thermal decomposition of racecadotril in air [J]. ACA Chem Sin( ), 006, a /kj mol 1 /Log[A min 1 ] ab he kinetics parameters of CDZ at different conversion degrees (5): [] ZHANG JCHN D HANG W Jet al. A kinetic study of the non-isothermal decomposition of ebstine and its thermal stability [J]. Chin Pharm J(), 001, 36(1): [3] ZHANG JSHNG R LMAI W P. Studies on the thermal decomposition processand kinetics of purine drugs[j]. Acta Pharm Sin(), 00, 3(7-8): [4] HAN SZHU X M. hermal analysis of norfloxacin [J]. Chin New Drugs J(), 007, 16(14): [5] LI A JZHOU X QLI Wet al. Synthesis of cefodizime disodium [J]. Chin J Antibiot(), 005, 30(6): CDZ (CDZ)CDZ Chin [6] Standard est Method for Decomposition Kinetics by hermogravimetry [S]. ASM [7] OZAWA. A new method of analyzing thermogravimetric data [J] Bull Chem Soc Jpn, 1965, 38(11) [8] FLYNN J H, WALL L A. A quick, direct method for the determination of activation energy from thermogravimetric data [J]. J Polym Sci B, 1966, 4(3) [9] DAKIN W. lectrical insulation deterioration treated as a chemical rate phenomena [J]. AI ransactions, Part I (Communication and lectronics), 1948, 67: JMAP, 009 December, Vol.6 No.1 103