有机化学课件14碳水化合物

第十四章碳水化合物•基本概念•单糖•糖苷•双糖•多糖糖：碳水化合物，通式：Cn(H2O)mCHOOHHHHOOHHOHHCH2OH•碳水化合物：多羟基醛或多羟基酮，以及能水解生成多羟基醛或多羟基酮的一类化合物。C6H12O6C12H22O11C6H12O5CH2O×C2H4O2×葡萄糖蔗糖鼠李糖甲醛乙酸葡萄糖碳水化合物糖是一切生物能量的主要来源。动物和植物通过如下的循环维持了二氧化碳与氧的平衡CO2OH2C6H12O6O26+6+6植物光合作用动物呼吸作用光植物CO2H2OO2C6H12O6分类：单糖：不能水解的多羟基醛、酮。寡糖（低聚糖）：能分解为2-10个单糖。双糖(贰糖)最常见。多糖（高聚糖）：能分解为几百、几千个单糖醛糖：葡萄糖酮糖:果糖碳原子数分：丁糖，戊糖，己糖一、单糖CHOCHOHCHOHCH2OHCH2OHCHOHCH2OHCOCHOCHOHCHOHCHOHCH2OHCH2OHCHOHCHOHCOCH2OHCHOCHOHCHOHCHOHCHOHCH2OHCH2OHCHOHCHOHCOCHOHCH2OH丁醛糖丁酮糖戊醛糖戊酮糖已醛糖已酮糖相应的醛糖和酮糖是同分异构体分为醛糖和酮糖，自然界中五、六碳糖最普遍CHOOHHHHOOHHOHHCH2OHCHOOHHOOHOHCH2OHCHOCH2OH1、单糖的构型和命名•用费歇尔投影式表示，如D-葡萄糖•旋光异构体的数目：2n个，n为手性碳原子的个数D，L构型表示法：人为规定甘油醛的构型，并以其作为参考标准。构型与D-甘油醛相当的，叫D-型；与L-甘油醛相当的，叫L-型。由此确定出的构型叫相对构型。D-甘油醛L-甘油醛CHOOHHCH2OHCHOHHOCH2OHIIICOOHOHCH3HCOOHOHCH3HD-(-)-乳酸L-(+)-乳酸HYR'RD,L构型只考虑一个手性碳原子的构型。如结构的化合物。R，S标记法：糖类物质多用俗名。D、L表示构型，只考虑与羰基最远的手性碳原子HCHOOHCH2OHHOHCH2OHCHOHOHCH2OHCH2OHO(CHOH)n(CHOH)nCD-甘油醛D-醛糖D-酮糖碳链的增长HCHOOHCH2OHHCNHHOHOHCH2OHCNHHOHCH2OHCNHOHHOHOHCH2OHCHOHHOHCH2OHCHOHO+(A)(B)D-甘油醛D-赤藓糖D-苏阿糖醛糖的D型异构体CHOOHCH2OHCHOCH2OHCHOCH2OHCHOCH2OHCHOCH2OHCHOCH2OHCHOCH2OHCHOCH2OHCHOCH2OHCHOCH2OHCHOCH2OHCHOCH2OHCHOCH2OHCHOCH2OHCHOCH2OHD-(+)-甘油醛D-(-)-赤藓糖D-(-)-苏阿糖D-(-)-核糖D-(-)-阿拉伯糖D-(+)-木糖D-(-)-莱苏糖丁醛糖戊醛糖己醛糖D-(+)-阿洛糖D-(+)-阿卓糖D-(+)-葡萄糖D-(+)-甘露糖D-(-)-古罗糖D-(-)-艾杜糖D-(+)-半乳糖D-(+)-塔罗糖酮糖的D型异构体OHOHCH2OHCH2OHOHOHCH2OHCH2OHHOHOOHHCH2OHCH2OHHOHOHOHCH2OHCH2OHHOHHOHOOHHCH2OHCH2OHHOHHOHOHOHCH2OHCH2OHOHHHOHOOHHCH2OHCH2OHOHHHOHCCCCCCCCCCCCCCCCCCCCCCCCD-赤藓酮糖D-木酮糖D-核酮糖D-塔格糖D-山梨糖D-果糖D-阿洛酮糖对映异构体和非对映异构体：CHOCH2OHCHOCH2OHD-(+)-葡萄糖L-(+)-葡萄糖对映异构体•D-葡萄糖在不同条件下结晶，得到2种晶体a-型—mp146℃，[a]D+112.2°b-型—mp150℃，[a]D+18.7°•葡萄糖溶液存在变旋光现象（旋光性改变的现象，最终达到一个固定的值）a-型[a]D+112.2°→+52.7°–NMR,IR谱没有-CHO的特征峰•形成缩醛时只需要一分子醇。2、单糖的环形结构CHOOHHHHOOHHOHHCH2OH问题的提出结晶状态的单糖以环形半缩醛(或半缩酮)的形式存在成环后，形成一个新的手性碳原子。α型：苷羟基与C5(决定构型的C)的羟基同侧β型：苷羟基与C5的羟基异侧（苷羟基）OHOHOHHOCCHCCH环形半缩醛CCH2OHOHHOHOHHOHHHOHα-D-(＋)-葡萄糖D-(＋)-葡萄糖β-D-(＋)-葡萄糖苷羟基半缩醛羟基苷羟基[α]D：＋112°＋19°含量：36%极少64%平衡时溶液[α]D=＋52.5°CCH2OHOHHOHHOHHHOHHOCCH2OHOHHOHHOHHHHOHOα-D-(＋)-葡萄糖与β-D-(＋)-葡萄糖互为异头物β-D-(＋)-葡萄糖α-D-(＋)-葡萄糖透视式哈武斯(Haworth)式CHOCH2OHOHHOHOHHOHHHCHOHOH2COHHOHOHHOHHHCHOHOHHOHOHHOHHCH2OHOHHHHOHOHHOHOHCH2OHCHOHHHOHOHHOHCH2OHOH654321OOHHHHOHOHHOHHCH2OH旋转90°弯曲成环状C4－C5键旋转费歇尔投影式HOCHOHHHHOHOHOHCH2OHHOCHOHHHHOHOHOHHOCH2HOOHHHHOHOHHOCH2HOHHOOHHHHOHOHHOCH2OHH+b-D-吡喃葡萄糖a-D-吡喃葡萄糖HOOHHHHOHOHHOCH2OHHOHHHHHOHOHOHHOAora-D-吡喃葡萄糖A=HOCH2-葡萄糖的哈武斯透视式OOHOHHHHHHOHOHCH2OHOOHHHHOHOHHOHHCH2OHOHHHHOHOHHOHOHCH2OHOHOHHHHHOHOHOHCH2OHα型，36%β型，64%构象式果糖的吡喃环形半缩醛和呋喃环形半缩醛HOOHOHCH2OHHHHOCH2OHHOOHOHCH2HHHOOHHOCH2HOOHOHCH2HHHOCH2OHHOHOOHOCH2OHHHHOHHOCH2HOOHOCH2OHHHHCH2OHHOCCCCCα-D-吡喃果糖β-D-吡喃果糖α-D-呋喃果糖β-D-呋喃果糖D-果糖果糖的结构有变旋现象。五种构型可相互转化，最终达成平衡。OO呋喃吡喃α-D-(－)-吡喃果糖β-D-(－)-呋喃果糖α-D-(－)-呋喃果糖β-D-(－)-吡喃果糖D-(－)-果糖(开链式)123456CH2OHCH2OHOHOHOHOHHHCH2OHHOH2COHOHOHOHHHOCH2OHOHHOHOHHHOH2CHOOHCH2OHHOHOHHHOH2CHOOHOHHHOHHOHHCH2OHHOCH2OHOHHHOHHOHHOHHCH2OHOHHHOHHOHHOHOH旋转90。弯曲成环状3、单糖的物理性质单糖都是无色晶体，有甜味。水中溶解度大。过饱和溶液：糖浆。变旋现象α-D-葡萄糖溶液：+112o+52.7oβ-D-葡萄糖溶液：+18.7o+52.7o4、单糖的化学性质具有醇、醛酮的性质：成醚、酯；氧化；加成等。(1)氧化•醛糖、酮糖都能被吐伦试剂、斐林试剂、本尼迪特（Benedict)试剂（硫酸铜、碳酸钠、柠檬酸钠混合液）氧化。•本尼迪特试剂：硫酸铜、碳酸钠、柠檬酸钠混合液。氧化亚铜•用作单糖的定性和定量鉴定。CH=OOHHHOOHHOHHCH2OHHCOOHOHHHOOHHOHHCH2OHHD-葡萄糖酸D-葡萄糖or本尼迪特试剂斐林试剂or土伦试剂•酮糖不能被溴水氧化，可用溴水来区别醛糖和酮糖。例：葡萄糖和果糖CHOCH2OHOHOHHOOHHHHHBr2HNO3COOHCH2OHOHOHHOOHHHHHCOOHCOOHOHOHHOOHHHHHCHOCOOHOHOHHOOHHHHHH2OD-葡萄糖D-葡萄糖酸D-葡萄糖二酸D-葡萄糖醛酸（2）还原D-(＋)-葡萄糖D-(＋)-葡萄糖醇CHOCH2OHOHHOHOHHOHHHH2/NiCH2OHCH2OHOHHOHOHHOHHHD-山梨醇D-甘露醇D-果糖H2/NiCH2OHCH2OHOHOHOHOHHHCH2OHCH2OHHHOHOHOHOHHHCH2OHCH2OHHHOHHOHOHHOH+（3）成脎反应D-(＋)-葡萄糖D-(＋)-葡萄糖苯腙D-(＋)-葡萄糖脎-H2OCH2OHCHOHHOHHOHOHHOHC6H5NHNH2CH2OHCHHHOHHOHOHHOHNNHC6H5-C6H5NH2-NH32C6H5NHNH2CH2OHCCHHHOHOHOHHNNNHC6H5NHC6H5D-(－)-果糖D-(－)-果糖苯腙D-(－)-果糖脎鉴别糖的重要反应。成糖脎的时间不一样，糖脎不溶于水，有特定的熔点和晶形。-H2OCH2OHCH2OHOHOHOHOHHHC6H5NHNH2CH2OHCCH2OHHHOHOHOHHNNHC6H5-C6H5NH2-NH32C6H5NHNH2CH2OHCCHHHOHOHOHHNNNHC6H5NHC6H5CHOCH2OHOHOHHOOHHHHHCHOCH2OHOHOHHOHHHHCH2OHCH2OHOHOHHOHHHHOOCHCH2OHOHOHHOHHHNNHC6H5NNHC6H5D-葡萄糖CD-甘露糖D-果糖C利用成脎反应可把醛糖转变成酮糖。D-(＋)-葡萄糖D-(＋)-葡萄糖脎醛酮糖D-(－)-果糖CHOCH2OHOHHOHOHHOHHHC6H5NHNH2CH2OHCCHHHOHOHOHHNNNHC6H5NHC6H5CH2OHCH2OHOHOHOHOHHHCH2OHCCHOHHOHOHOHHOHClZn-HAc（4）差向异构化只有一个手性碳原子构型相反者，彼此成为差向异构体：•单糖与稀碱共热则发生异构化反应。D-(－)-果糖D-(＋)-葡萄糖D-(＋)-甘露糖在稀碱溶液中，酮糖能转变成醛糖，可发生斐林反应和银镜反应。CH2OHCH2OHOHOHOHOHHHCHCCH2OHOHHOHOHOHHHOHCHCCH2OHOHHOHOHOHHHOHCH2OHCHOHHOHOHOHOHHHCH2OHCHOHHOHHOHOHHOH顺烯醇式反烯醇式（5）莫利施(Molish)试验•糖的水溶液中加入α-萘酚的酒精溶液，沿试管壁小心地注入浓硫酸，不要摇动试管，在两层液面间可形成一个紫色环。•用于鉴别糖类。所有的糖都有这种反应。（6）成苷反应半缩醛(酮)可继续和醇作用形成缩醛(酮)，糖的缩醛(酮)叫糖苷配糖体糖苷键OHHOHHOOHOCH2OHHHHHCH3OHOMeHOHHOOHOCH2OHHHHHCD-葡萄糖无水HClC甲基-α-D-葡萄糖苷+甲基化法甲基-α-D-葡萄糖苷甲基-2,3,4,6-四-O-甲基-α-D-葡萄糖苷5、半缩醛环的大小测定2,3,4,6-四-O-甲基-α-D-葡萄糖OHOHHHHOHHOHCH2OHOα-D-葡萄糖OHOHHHHOHHOMeCH2OH(CH3)2SO4NaOHOMeOMeOMeOMeCH2OCH3OOOMeOMeOMeOHCH2OCH3MeOOMeOCH2OCH3OMeCOHHCHOMeOOMeOHCH2OCH3OMeHNO3COOHMeOOMeCOOHCOOHMeOOMeCOOHOMeO+123456123451234CH2OCH3COOH+56高碘酸法CH=OOHHHOOHHOHHCH2OHH5HCOOH+CH2O5HIO4OOCH3HHHOHOHHOHHCH2OH123452HIO4OHCHO3+OHCHCOCH3HOOHCH2OH1245H2O,H+CH2OHCHOHCHOCHOCHO12+456666、重要的单糖1D-核糖及D-2-脱氧核糖核糖核酸及脱氧核糖核酸的重要组分CHOOHOHCH2OHOHOOHOHCH2OHOHOOHOHCH2OHOHCHOHOHHCH2OHOHOHOHCH2OHOHOHOHCH2OHOHα-D-核糖D-核糖β-D-核糖α-D-2-脱氧核糖D-2-脱氧核糖β-D-2-脱氧核糖2.D-葡萄糖(右旋糖)存在于葡萄等水果中。无色结晶。易溶于水