L-葡萄糖和D-葡萄糖单他糖两大物质特点
来源：http://www.jnjdbc.com 日期：2019-06-21 发布人：admin
（一）物理性质
(1) Physical properties
单糖都是无色晶体，味甜，有吸湿性。极易溶于水，难溶于乙醇，不溶于乙醚。单糖有旋光性，其溶液有变旋现象。
Monosaccharides are colorless crystals, sweet and hygroscopic. It is very soluble in water, insoluble in ethanol and insoluble in ether. Monosaccharides have optical rotation, and their solution has the phenomenon of rotation.
（二）化学性质
(2) Chemical properties
单糖主要以环状构造方式存在，但在溶液中可与开链构造反响。因而 ，单糖的化学反响有的以环式构造停止，有的以开链构造停止。
Monosaccharides mainly exist in the form of ring structure, but they can react with open-chain structure in solution. Therefore, some chemical reactions of monosaccharides stop with ring structure and others stop with open chain structure.
1．差向异构化
1. Episomerization
葡萄糖用稀碱液处置时，会局部转变为甘露糖和果糖，成为复杂的混合物。这咱变化是通老祖宗醇式中间体来完成的。
When the glucose is treated with dilute alkali solution, it will locally transform into mannose and fructose, and become a complex mixture. This change was accomplished by the alcoholic intermediates of Tonglao ancestors.
D-果糖、D-甘露糖和D-葡萄糖的C-3、C-4，C-5和C-6的构造完整相同，只要C-1和C-2的构造不同，但是它们的C-1，C-2的构造互变成烯醇型时，其构造完整相同的。因而，不单是D-葡萄糖，而D-果糖或D-甘露糖在稀碱催化下，都能互变为三者的混合物。
The structures of C-3, C-4, C-5 and C-6 of D-fructose, D-mannose and D-glucose are identical, as long as the structures of C-1 and C-2 are different, but their C-1 and C-2 structures are identical when they become enol-like. Therefore, not only D-glucose, but also D-fructose or D-mannose can be mutually transformed into a mixture of the three under the catalysis of dilute alkali.
在含有多个手性碳原子的具有旋光性的异构体之间，凡只要一个手性碳原子的构型不同时，互称为差向异构体。D-葡萄糖和D-甘露糖就是C-2差向异构体。因而，用稀碱处置D-葡萄糖得到D-葡萄糖、D-果糖三种物质的均衡混合物的反响叫做差向异构化。
Among the optically active isomers containing more than one chiral carbon atom, if only one chiral carbon atom has different configurations, they are called epimers. D-glucose and D-mannose are C-2 epimers. Therefore, the reaction of the equilibrium mixture of D-glucose and D-fructose obtained by treating D-glucose with dilute alkali is called epimerization.
2．氧化作用
2. Oxidation
单糖无论是醛糖或酮糖都可与弱的氧化剂叶伦试剂、费林试剂和本尼迪特试剂作用，生成金属或金属的低价氧化物。上述三种试剂都是碱性的弱氧化剂。单糖在碱性溶液中加热，生成复杂的混合物。
Monosaccharides, whether aldose or ketose, can react with weak oxidants such as Yellen reagent, Ferrin reagent and Benedict reagent to form low-valent oxides of metals or metals. The three reagents mentioned above are alkaline weak oxidants. Monosaccharides are heated in alkaline solutions to form complex mixtures.
单糖易被碱性弱氧化剂氧化阐明它们具有复原性，所以把它们叫做复原糖。
Monosaccharides are readily oxidized by alkaline weak oxidants to clarify their resilience, so they are called resilient sugars.
单糖在酸性条件下氧化时，由于氧化剂的强弱不同，单糖的氧化产物也不同。例如，葡萄糖被溴水氧化时，生成葡萄糖酸；而用强氧化剂硝酸氧化时，则生成葡萄糖二酸。
When monosaccharides are oxidized under acidic conditions, the oxidation products of monosaccharides are different because of the different oxidants. For example, when glucose is oxidized by bromine water, it produces gluconic acid, while when oxidized by nitric acid, it produces gluconic acid.
溴水氧化才能较弱，它把醛糖的醛基氧化 为羧基。当醛糖中参加溴水，稍加热后，溴水的棕色即可褪去，而酮糖则不被氧化，因而可用溴水来区别醛糖和酮糖。
Bromine water oxidizes the aldehyde group of aldose to carboxyl group. When bromine water is added to aldose, the brown color of bromine water can be faded after a little heating, while ketose is not oxidized, so bromine water can be used to distinguish aldose from ketose.
3．成苷作用
3. Glycosidation
单糖环状半缩醛构造中的半缩醛羟基与另一分子醇或羟基作用时，脱去一分子水而生成缩醛。糖的这种缩醛称为糖苷。例如α-和β-D-吡喃葡萄糖的混合物，在氯化氢催化下同甲醇反响，脱去一分子水，生成α-和β-D-甲基吡喃葡萄糖苷的混合物。
When the hydroxyl group of hemiacetal in the structure of monosaccharide cyclic hemiacetal reacts with another molecule alcohol or hydroxyl group, one molecule of water is removed to form acetal. This acetal of sugar is called glycoside. For example, a mixture of alpha-and beta-D-glucopyranose reacts with methanol catalyzed by hydrogen chloride, removes a molecule of water, and produces a mixture of alpha-and beta-D-methyl-glucopyranoside.
α-和β-D-吡喃葡萄混合液 β-D-甲基吡喃葡萄糖苷 α-D-甲基吡喃葡萄糖苷，苷由糖和非糖局部组成。非糖局部称为糖苷配基或苷元。糖和糖苷配基脱水后经过过“氧桥”衔接，这种键称为苷键。由于单糖的环式构造有α-和β-两种构型，所以可生成α-和β-两种没构型的苷。自然苷多为β-构型。苷的称号是按其组成成分而命名的，并指出苷键和糖的构型。自然苷常按其来源而用俗名。
The mixture of alpha-and beta-D-glucopyranoside is beta-D-methyl-glucopyranoside alpha-D-methyl-glucopyranoside, which is locally composed of sugar and non-sugar. Non-sugar is locally called glycoside ligand or aglycone. Sugar and glycoside ligands are dehydrated and then bonded by "oxygen bridge", which is called glycoside bond. Because the cyclic structure of monosaccharides has two configurations of alpha and beta, two kinds of non-configurable glycosides, alpha and beta, can be formed. Natural glycosides are mostly beta-configurations. Glycosides are named after their constituents, and the structures of glycoside bonds and sugars are pointed out. Natural glycosides are commonly used as common names according to their origin.
糖苷构造中已没有半缩醛羟基，在溶液中不能再转变成开链的醛式构造，所以糖工苷无复原性，也没有变旋现象。糖苷在中性或碱性环境中较稳定，但在酸性溶液中或在酶的作用下，则水解生成糖和非糖局部。
Glycosides have no semiacetal hydroxyl group and can no longer be converted into open-chain aldehyde structure in solution. Therefore, glycosides have no resilience and no rotation phenomenon. Glycosides are stable in neutral or alkaline environments, but in acidic solutions or under the action of enzymes, they hydrolyze to form sugars and non-sugars locally.
糖苷是中草药的有效成分之一，多为无色、无臭、有苦涩味的固体，但黄酮苷和蒽醌苷为黄色。
Glycosides are one of the effective components of Chinese herbal medicine. Most of them are colorless, odorless, bitter and astringent solids, but flavonoid glycosides and anthraquinone glycosides are yellow.
苷中含有糖局部，所以在水中有一定的溶解性。苷类都有旋光性，自然苷多为左旋体。
Glycosides contain sugar locally, so they are soluble in water. Glycosides are optically active, and natural glycosides are mostly levotropic.
4．成酯作用
4. Esterification
单糖分子中含多个羟基，这些羟基能与酸作用生成酯。人体内的葡萄糖在酶作用下生成葡萄糖磷酸酯，如1-磷酸吡喃葡萄糖和6-磷酸吡喃葡萄糖等。
Monosaccharide molecule contains many hydroxyl groups, which can react with acid to form esters. Glucose in human body produces glucose phosphate esters under the action of enzymes, such as 1-phosphate pyran glucose and 6-phosphate pyran glucose.
单糖的磷酸酯在生命过程中具有重要意义，它们是人体内许多代谢的中间产物。
Phosphates of monosaccharides are important in the process of life. They are intermediate products of many metabolism in human body.
5．成脎反响
5. Chengsai Response
单糖分子与三分子苯肼作用，生成的产物叫做糖脎。例如葡萄糖与进量苯肼作用，生成葡萄糖脎。
The monosaccharide molecule interacts with the three-molecule phenylhydrazine to produce a product called saccharose. For example, glucose reacts with phenylhydrazine to produce glucosamine.
无论是醛糖还是酮糖都能生成糖脎，成脎反响能够看作是α-羟基醛或α-羟基酮的特有反响。
Both aldose and ketose can produce saccharose. The reaction of saccharose formation can be regarded as a specific reaction of alpha-hydroxyaldehyde or alpha-hydroxyacetone.
糖脎是难溶于水的黄色晶体。不同的脎具有特征的结晶外形和一定的熔点。常应用糖脎和这些性质来鉴别不同的糖。
Saccharine is a yellow crystal that is insoluble in water. Different samarium has characteristic crystalline shape and certain melting point. Sarcandra and these properties are often used to identify different sugars.
成脎反响只在单糖分子的C-1和C-2上发作，不触及其它碳原子，因而除了C-1和C-2以外碳原子构型相同的糖，都能够生成相同的糖脎。例如：D-葡萄糖和D-果糖都 生成相同的脎。
Sarcandrium reactions occur only on C-1 and C-2 of monosaccharide molecules and do not touch other carbon atoms. Therefore, sugar with the same carbon atom configuration except C-1 and C-2 can produce the same saccharide. For example, D-glucose and D-fructose both produce the same anthraquinone.
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