李艳梅有机化学 第二十四章

Chapter24Carbohydrates第二十四章碳水化合物OrganicChemistryA(2)ByProf.LiYan-MeiTsinghuaUniversityContents24.1单糖24.2二糖24.3多糖24.4糖的衍生物二糖Disaccharides多糖Poly-saccharides糖的衍生物Derivatives单糖MonosaccharidesxCO2+yH2OCx(H2O)y+O2在叶绿素的作用下光合作用叶绿体代谢时EmilFischerHaworthCm(H2O)n从本质上而言，碳水化合物本身或水解后为多羟基醛或多羟基酮OHOHOOHOHC6H12O5鼠李糖乳酸C3H6O3羟基酸碳水化合物糖的分类：单糖（Monosaccharide）：较简单的，不能再水解的羟基醛或多羟基酮及其衍生物CHOCHOHCHOHCHOHCHOHCH2OH葡萄糖CH2OHCOCHOHCHOHCHOHCH2OH果糖醛糖酮糖寡糖（低聚糖oligo-saccharido）：由两分子单糖缩合而成的为双糖由三分子单糖缩合而成的为三糖………多糖(poly-sacchatide)：由多个单糖缩合而成OHHOHHOHHOHHOHOHOHHOHHOHHOOHOHHHOHHOHHOHOHOHHOHHOHHOHOHnOHHOHHOHHOHHOHOHOHHOHHOHHOOHOHHHOHHOHHOHOHOHHOHHOHHOHOHn淀粉纤维素24.1单糖24.1.1单糖的构造式Problem1确定葡萄糖的构造NaBH4OHOHOHOHOHOHKINH2OHorHCNAdditionproducts[O]COOH5molAc2OCH3COOCH3COOCH3COOCH3COOCH3COOOHC？葡萄糖Problem1确定葡萄糖的构造NaBH4OHOHOHOHOHOHKINH2OHorHCNAdditionproducts[O]COOH5molAc2OOHOHOHHOHOOCH3COOCH3COOCH3COOCH3COOCH3COOOHCProblem2确定果糖的构造NaBH4OHOHOHOHOHOHKINH2OHorHCN2’Additionproducts[O]5molAc2O？果糖OCCH3COOCH3COOCH3COOCH3COOCH3COOOOHOHHOHOOHProblem2确定果糖的构造NaBH4OHOHOHOHOHOHKINH2OHorHCN2’Additionproducts[O]5molAc2O果糖OCCH3COOCH3COOCH3COOCH3COOCH3COOOthersaccharides其它糖HOOHHO*立体异构体的数目:N=2n=21=2异构体CHOOHHCH2OHCHOHOHCH2OH立体异构体的数目:N=2n=24=16异构体最多时OHOHOOH**OH*OH*立体异构体的数目:N=2n=23=8异构体最多时OHOHOOHH**OH*立体异构体的数目:N=2n=22=4异构体最多时OHOHOOHH**Fischer’sformulaisoftenemployed24.1.2单糖的构型CHOOHHCH2OHCHOHOHCH2OHD-GlyceraldehydeL-Glyceraldehyde以D-甘油醛为基准物衍生出的均为D-型结构衍生出的均为L-型结构HOHCHOOHHCH2OHCN-CN-D-GlyceraldehydeHOHCNOHHCH2OHH2OH2ONa(Hg)Na(Hg)HOHCHOOHHCH2OHD-(-)-ErythritolD-(-)-赤藓糖D-(+)-BoSUsugarD-(+)-苏阿糖HOHCNOHHCH2OH赤式苏式平面型羰基，两面均可被进攻DDCCCDCDThreo苏式Erythro赤式CHOHOHCH2OH由L-甘油醛可衍生出这两种糖的对映体L-GlyceraldehydeHOHCOOHHHOCH2OHL-(-)-BoSUsugarL-(-)-苏阿糖HOHCOOHHHOCH2OHL-(+)-ErythritolL-(+)-赤藓糖D-GlyceraldehydeD-(-)-ErythritolD-(+)-BoSUsugarForCHOForOHForCH2OHD-(-)-赤藓糖D-(+)-苏阿糖L-GlyceraldehydeL-(-)-ErythritolL-(+)-BoSUsugar差向异构体EPIMERIDES差向异构体差向异构体（EPIMERIDES）：含有多个不对称碳的异构体，相应的不对称碳只有一个构型不同，其余构型都相同的异构体为差向异构体。几个糖的结构需要掌握：及其对映异构体D-(+)-甘油醛D-(-)-核糖D-(+)-半乳糖D-(+)-葡萄糖OD-(-)-果糖HOOHHHNH2NHNOHHHHNH2NHNOHHNH2NHNNHNH24.1.3单糖的反应及应用（一）生成糖脎苯肼苯腙（糖）脎O+HNH2NNNHOC=N-NH-C6H5C=N-NH-C6H5C=N-NH-C6H5C=N-NH-C6H53C6H5NH-NH2yellow3C6H5NH-NH2yellow可用于推测结构D-葡萄糖D-甘露糖D-果糖D-葡萄糖脎3％28％（二）差向异构化条件：弱碱性结果：与羰基相邻的不对称碳原子构型发生改变同时还发生醛糖与酮糖的相互转化D-葡萄糖D-甘露糖D-果糖HOOHHOHHOOHHOOHH2OHOHHO-H2H2OHOHHOHOHOHOHOHOHO％％差向异构化HOOFehlingreagentCuSO4+酒石酸钾钠＋NaOHTollensreagentAgNO3+NH3·H2OCu2+Ag2OCu2OAg（三）氧化1、被Tollens试剂和Feling试剂氧化砖红色黑色银镜反应弱氧化剂还原糖：凡是能被Tollens试剂及Feling试剂这一类弱氧化剂氧化的糖为“还原糖”否则为“非还原糖”。葡萄糖还原糖甘露糖醛糖酮糖？果糖是还原糖！HOOHHOHHOOHHOOHH2OHOHHO-H2OH2OHOHHOHOHOHOHOHOHOKey：这些弱氧化剂均为碱性试剂OHOBr2,H2OpH=5OHHOHHOHOOHHOHOHHOHHOHOHHOHO2、被溴水氧化Key：溴水为酸性试剂只氧化醛糖，不氧化酮糖红褐色褪去OOCa0.5O3、被硝酸氧化Key：硝酸氧化性很强HNO3OHOOOH100oCD-葡萄糖二酸OOHHOHHOOO生成的糖二酸是否有旋光性，可用于糖构型的测定。例如：某一丁醛糖A，硝酸氧化后的产物无旋光，则A中两个羟基于同侧。OHOHNO3OHNO3HNO3酮糖在同样条件下氧化，导致1-2键断裂OOHD-异木糖D-树胶糖D-树胶糖二酸D-果糖H5IO6HCOOHHCOOHHCOOHHCOOHHCOOHHCHOOHOH5IO64、被高碘酸氧化可用于结构推测可参见“多元醇”部分NaBH4NaBH4ONaBH4+mixtureNaBH4（四）还原D-葡萄糖D-古洛糖D-果糖D-甘露糖甘露醇山梨醇CNCNCOOHCOOHH+H2OH2OH+Na(Hg)Na(Hg)H2OH2O（五）醛糖的递升和递降递升平面型羰基，两面均可被进攻递升：由一个醛糖变为高一级的醛糖递减：由一个醛糖变为低一级的醛糖OCH3AcOOAcOAcNH2OHCHNOH(CH2CO)2OHighTemp.CNOAcOAcOAcAcOCHNONO2NO2CNOHMeOMeOH-AcO=OCNH3C(NHCOCH3)2H+递降FO2NNO2COOCa0.5electrolysisH2O2,Fe3+COOHOBr2,H2OpH=5COOH-CO2ODarkRedLightRedOHOHHCl+（六）酮糖的特殊反应1、与盐酸－间苯二酚OCa(OH)2C6H12O6·Ca(OH)2·H2O2、与Ca(OH)2可以用来鉴别果糖24.1.4单糖的环状结构AdditionreactionwithCN-AdditionreactionwithNH2OHNoNaSO3additionOpticalActivityVariationAdditionreactionwith1molalcohol1、事实变旋现象：常温下用水或用乙醇结晶得到的D-葡萄糖m.p.:146C水溶液比旋光度：＋112（新配）放置后旋光度逐渐减少至达到平衡时的D＝＋52高温下用醋酸或吡啶结晶或浓溶液保持在110C时蒸发得到的D-葡萄糖m.p.:150C水溶液比旋光度：＋19（新配）放置后旋光度逐渐增高至达到平衡时的D＝＋52差向异构化？存在“环状结构”CHOCCCCCH2OHOHHHOHOHOHHH123456CCCOCHOHCHCH2OHHOHHOHOHH123456CCCCCCH2OHOHHHOHOHHH123456HOHO半缩醛式羟基（苷羟基）糖苷基CH3OH/H+配质，配基CCCCCCH2OHOHHHOHOHHHHOCH3O配糖物（苷）葡萄糖甲苷OHHHHOOHHHHOCH2OHOHOHHHHOOHOHHHHOCH2OHWhichisthetruestructure?OHHOHHOHOHOHHHOHOHHHHOOHOHHHOHCH2OHOHHOHHOHHOHHOHOHOHHHHOHHOHOHHOHOHOHHHOHHOHOHHOHOOHHHHOOHHHHOCH2OHOHOHHHHOOHOHHHHOCH2OHOHHHHOOCH3HHHOCH2OHOHOHHHHOOHOCH3HHHOCH2OHOCH3HHH3COOCH3HHHOCH2OCH3OCH3OCH3HHH3COOCH3OCH3HHHOCH2OCH3OCH3HHH3COOHHHHOCH2OCH3OCH3OCH3HHH3COOCH3OHHHHOCH2OCH3H+H+OCH3HHH3COOHHHCH2OCH3OHOCH3OCH3HHH3COOCH3OHHHCH2OCH3OH确定环的位置DenotationoftheringconformationFischer投影式2、表示方法直立环状投影式OHHHHOOHHHHOCH2OHOHOHHHHOOHOHHHHOCH2OHOHHHOHCHOHOHCH2OHHOHOHHOHHOHHOHHOHOHOHHOHHOHOHOHHHOH～37%～63%Haworth式HHOHCHOCH2OHHOHHOHOHHHOHCCH2OHHOHOHOHOHHHHOHCCH2OHHOHOHOHHOHβ-型-型HOHHHOOHHOHHCH2OHOHHOH2CHOHHOHOHHHOHOHOHHOHHOHOHOHHHOHOHHOHHOHHOHHOHOHm.p.146oC150oC+112o+19o～37%～63%异头碳型与β型互为非对映异构体，也称“异头物”酶可区分两种不同的构型：麦芽糖酶可分解型葡萄糖甲苷苦杏仁酶可分解β型葡萄糖甲苷3、环式和链式异构体之间存在着平衡OHHOHHOHOHOHHHOHOHHHHOOHOHHHOHCH2OHOHHOHHOHHOHHOHOH~0.1%~37%~63%112o×37%+19o×63%=52o.4、环式与链式异构体的互变可解释：变旋现象与NaHSO3等不反应5、单糖的构像~37%а-型~63%β-型OHHOHHOHOHOHHHOHOHHHHOOHOHHHOHCH2OHOHHOHHOHHOHHOHOH~0.1%HHOOHHHOCH2OHOHHOOHHOHHCH2OHCH2OHOHOHCH2OHOHHHCH2OHOHCH2OHOHOHOHCH2OHOHOHHOHHHHOHOHCH2OHOHOHHOHHHH6、酮糖的环式结构呋喃式吡喃式24.2二糖24.2.1概述+-H2O二糖单糖问题之一：由哪两个单糖缩合而成？问题之二：用什么方式连接A糖B糖HHOCH2OHOHHCH2OHOO-H2OHCH2OHOHCH2OHOOOHHCH2OHO-H2OOHHCH2OHHOOHCH2OHOOHHCH2OHOO两个苷羟基缩合一个苷羟基与一