第25卷第3期河北師范大學(xué)學(xué)報(自然科學(xué)版)Vol 25 No. 3G0i年9月Journal of Hebei Normal University(Natural Science Edition)氟哌酸熱分解動力學(xué)的研究張建軍,白繼海(1.可北師范大學(xué)實驗中心,河北石家莊0500162,河北職業(yè)技術(shù)師范學(xué)院計算機系河北昌黎06600摘要:采用 TG-DTG技術(shù)研究了氟哌酸的熱分解動力學(xué)運用 Coats-Redfern法、 Horowitz-Metzger法、 Madhusudanan- Krishnan-Ninan法和 Kissinger法得到了氟哌酸第二步熱分解的動力學(xué)參數(shù)及熱力學(xué)參關(guān)鍵調(diào):熱重分析;動力學(xué);氟哌中圖分類號:TQ460.72文獻標識碼A文章編號:10005854(2001)03-0352-02氟哌酸,屬于含氟喹諾酮類化合物,在臨床上被廣泛用于尿道感染、腸道感染等領(lǐng)域療效顯著們有關(guān)氟哌酸的熱分析研究已有報道(2).但關(guān)于氟哌酸熱分解動力學(xué)的研究尚未見報道本文主要采用Coats-Redfern(CR)法、 Horowitz- Metzger(HM法、 Madhusudanan-Krisbnan- Ninan(MKN)法和Kissinger法計算了氟哌酸第二步熱分解過程的動力學(xué)參數(shù)1實驗部分1.1樣品氟哌酸(太原制藥廠),實驗前未做任何處理1.2儀器及測試條件TG-DTG實驗使用美國 Perkin-Elmer公司的TGA7熱重分析儀完成,升溫速率為5,7,10和5C/min.實驗的溫度范圍為25~600℃,試樣質(zhì)量為(2.7±0.2)mg,流動氮氣氣氛40mL/min2結(jié)果與討論氟哌酸使用升溫速率為15c/min的TG-DTG曲線見圖1.由DTG曲線可知,在實驗溫度范圍內(nèi)氟哌酸熱分解主要分為三步,第一步分解約從29~132℃之間失重率為878%,對應(yīng)水分的去除,實際上這步分解呈明顯的兩個失重臺階,表明該樣品中所含水至少以兩種形式存在;第二步分解在132369℃之間,失重率為4893%(理論失重47.50%),對應(yīng)側(cè)環(huán)的破裂第三步分解在369~519C之間失重率為22.10%(理論失重2.88%),對應(yīng)母環(huán)的破裂2本文釆用CR、HM和MKN方程計算了氟哌酸第二步熱分解反應(yīng)的活化能E及指前因子A.其使用方程如下:CR方程lng(a)/T72=lnAR/BE(1-2RT/E)-E/RTHM方程lng(a)= InART/BE-E/RT,+E/RT2MN方程lng(a)/T33=nAE/R+3.7721-1.92l5lnE-0.12039E/T(3)這里g(a)=[1-(1-a)]/(1-n),n=1時,g(a)=-ln(1-a)a為分解率,n為反應(yīng)級數(shù),T為溫度(K)R為氣體常數(shù),為DTG的峰溫,β為升溫速率,6=T-T中國煤化工CNMHG收稿日期:2000-11-13;修回日期:2001-02-15基金項目:河北師范大學(xué)科學(xué)研究基金資助項目(L2000y08)作者簡介:張建軍(1964)男河北深澤人,河北師范大學(xué)副研究員,光譜實驗室雜志副主編研充方向為熱分析動力學(xué)第3期張建軍等:氟哌酸熱分解動力學(xué)的研究35330009000150002100027000圖1瓶哌酸的 TG-DTG曲線從圖1的TG曲線上求得氟哌酸第二步熱分解反應(yīng)的基礎(chǔ)數(shù)據(jù)a和T列于表1.第二步熱分解反應(yīng)的級數(shù)n表1氟哌酸第二步熱分解過程的基礎(chǔ)數(shù)據(jù)(B=15 C/min由CR方程求得將g(a)=[1-(1-a)]/(1-n)的函No. a數(shù)和基礎(chǔ)數(shù)據(jù)aT代入方程(1),對于不同的n以0.1步長的間隔從0到3取值以lng(a)/T2對1/T采用自565760610編程序依據(jù)最小二乘法進行線性回歸分析,求得不同n20.10780.7061值下的相關(guān)系數(shù)得到相關(guān)系數(shù)(r=0.9990)最好時的n30.2058890.8061940.30596100.90626為1.1,這說明第二步熱分解反應(yīng)為一級反應(yīng)過程將50.40601110.95633=1.1和表1中的數(shù)據(jù)分別代入方程(1),(2)和(3)采用60.50606自編程序依據(jù)最小二乘法,求得動力學(xué)參數(shù)E、A和相關(guān)系數(shù)r計算結(jié)果列于表2熱力學(xué)參數(shù)的計算使用方程如下Aexp(-E/RT)=y exp(-AG/RT')MH=E一RT△G=△H-T△S(6)上式中y為愛因斯坦振動頻率將由上面的3個積分方程得到的E和A代入到方程(4)~(6)中,計算得到的熱力學(xué)參數(shù)列在表3中表2氟哌酸第二步熱分解的動力學(xué)參數(shù)表3氟哌酸第二步熱分解的熱力學(xué)參數(shù)InA/(kJ·mol-1)/(s-1)(kJ·mol-)/(J·mal-l)/(kJ·mol-)CR方法180,534.260.99901CR方法174.525MKN方法34.360.9990MKN方法175.8159.7HM方法197.837.730.9990HM方法192.7159.5平均值186,435.450.9990平均值81.3中國煤化工為了驗證利用單一掃描速率法中3個積分方程算得活化能的Kissinger方程重新計算了第二步熱分解反應(yīng)的活化能(E=19HCNMHG法中的,r=0.9815),送習(xí)CR法、MKN法和HM法獲得的活化能相比較,結(jié)果基本一致(下轉(zhuǎn)第364頁)364河北師范大學(xué)學(xué)報(自然科學(xué)版)第25卷[6]BOUKAMP B A. Equivalent Circuit Users Manual [M]. 2nd edn. Twente: Preston Company, 1993. 48[7] SABATANI E. RUBINSTEIN I Organized self-assembling monolayers on electrodes 2 Monolayer-based ultramcroelectrodes for the study of very rapid electrode kinetics []. J Phys Chem. 1987, 91:6 663-6669[8]藤島昭相澤益男,井上微電化學(xué)測定方法[M]陳震姚建年譯北京:北京大學(xué)出版社,1995.4.4[9] DIAO P,JIANG D L, CUI X L,et ul. Studies of structural disorder of self-assembled thiol monolayers on gold bycyclic voltammetry and ac impedance [J].J Electroanal Chem,1999,464:61The Formation of Self-assembled monolayerby schiff Base on Au SubstrateDING Ke-qiang, WANG Qing-fei. TIAN NaIONG Ru-ting', WANG Xin-kui, SHAO Hui-bo(1. Department of Chemstry Hebei Normal University, Hebei Shijiazhuang 050016.China2. Institute of Coat Chemistry Chinese Academy of Science Shanxi, Taiyuan 030001, China;3. Department of Chemistry. Capital Normal University Beijing 100tract: Self-assembled monolayer of schiff base, which was firstly formed on Au substinvestigated with cyelic voltammetry(CV)and Electrochemical Impedance Spectroscopy(EIS) meth-ods. All the results confirned their formation. the meaning of this work is to provide one valid self-assembled monolayer, which is crucial to probe the electrochemical behavior of schiff base.Key words; schiff base; self-assembled monolyer; electrochemical response(責任編輯邱麗)不心心?心>心>心心以4二以瀏心→心心心(上接第353頁)參考文獻[1牟兆吉,俞玉英,江濟章.!譜抗菌藥諾氟沙星的合成[]醫(yī)藥工業(yè),1987,18(5):203-205[2:殷生章,牛于華,王永東熱頭重分析在喹諾酮類藥物氟哌酸質(zhì)量監(jiān)控屮的應(yīng)用[A].中國化學(xué)會第九屆全國化學(xué)熱力學(xué)和熱分析學(xué)術(shù)論文年會暨北京國際華夏熱分析和量熱學(xué)術(shù)論文報告會論文摘要集[C]北京:北京航空航天大學(xué)出版社,1998.376-377[3] COATS A W REDFERN JD. Kinetic parameters from thermogravimetric data [Jj. Nature, 1964,201: 68-69.[4] HOROWITZ HH. METZGER G. Analysis of thermogravimetric traces []. Anal Chem, 1963, 35: 1 464-1 468[52 MADHUSUDHANAN P M, KRISHNAN K, NINAN K N, New approximation for the P(r) function in the evaluation of non-isothermal kinetic data [] Thermochem Acta, 1986,97: 189-201[63 KISSINGER H E Reaction kinetics in differential thermal analysis [].Anal Chem, 1957. 29: 1 702-1704[7] STRASZKO J, OLSTAK-HUMIENIK M MOZEJKO J. Kinetic of thermal decomposition of ZnSO.7H:O [J]mica Acta,l997,292:145-150[8 OLSTAK-HUMIENIK M, MOZEJKO J. Thermodynamic functions of activated complexes created in thermal decomposition processes of sulphates []. Thermochim Acta. 2000, 344:73-79.Thermal Decomposition Kinetics of NorfloxacinZHANG Jian-jun, BAI Ji-hai2bei Normal University, Hebei, Shijiazhuang 050016 Chi2. Computer Department, Hebei Teacher's Collage of Occupation Technology, Hebei, Changli 066600, China)Abstract: Under non-isothermal conditions, the thermal decomposition kinetics was studied usingthermogravimetric analysis method. The kinetic parametersters were中國煤化工btained by Coats-Redfern method, Horowitz-Metzgernan-Ninanmethod and KCNMHGKey words: thermogravimetric analysis; kinetics; norfloxacin(賁任編輯邱麗)