有机化合物中的官能团
碳氢化合物是由氢和碳组成的化合物,饱和碳氢化合物是碳原子仅通过一个单键连接的化合物。饱和烃是非反应性的,但当引入另一个“原子”或“原子组”时,所得分子会变得高度反应性。碳化合物中的另一个“原子”或“原子组”称为官能团。下面将进一步讨论各种官能团。
什么是官能团?
A functional group is an atom or a group of atoms that makes a carbon compound or an organic compound reactive and determines its properties.
官能团是分子中具有不同性质的原子,与分子中的其他原子无关。在有机化学中,官能团是与某些分子相连的取代基原子或原子团。官能团是物质中的一组原子或键,负责物质的独特化学反应。卤基、醇基、醛基、酮基、羧酸基、烯烃基、炔基是有机化学中一些最重要的官能团。以下部分将介绍这些组中的每一个。
晕组
取决于氯、溴或碘原子是否连接到有机化合物的碳原子上,卤素基团可以是氯(-Cl)、溴(-Br)或碘(-I)。由于元素氯、溴和碘统称为卤素,因此氯、溴和碘基被称为卤基并用符号-X表示。由于氯甲烷(CH 3 -Cl)含有氯基,溴甲烷(CH 3 -Br)含有溴基,而碘甲烷(CH 3 -I)含有碘基,所以卤基可以在氯甲烷、溴甲烷和碘甲烷。卤素基团是卤素基团的另一个名称。卤基是卤素基团的缩写。
Haloalkanes are formed when one hydrogen atom in an alkane is replaced with a halogen atom. Haloalkanes have the general formula CnH2n+1X, where X represents the halogens. R-X is the formula for haloalkanes, where R is an alkyl group and X is the halogen atom. Halogen atoms (Cl, Br, or I) serve as the heteroatom in haloalkanes.
酒精组
一个氧原子和一个氢原子结合在一起形成醇基(-OH)。醇基或羟基是醇基的另一个名称。醇是包含醇基的有机化合物。包括一个或多个与烷基的碳原子连接的羟基(OH)基团的任何类别的有机化合物都是醇基。
Alcohols are organic water (H2O) derivatives in which one of the hydrogen atoms has been replaced by an alkyl group, which is often represented by R in organic structures.
例如,乙基是乙醇C 2 H 5 OH(或乙醇)中的烷基。醇是通过用烷烃中的一个氢原子取代羟基而制成的。同系醇具有通式C n H 2n+1 OH。
最常见的有机化合物是醇。它们被用作甜味剂和制造香水,也是合成其他化合物的重要中间体。它们也是工业中生产最广泛的有机化学品之一。乙醇和甲醇(或甲醇)是最著名的两种醇。
醛组
One carbon atom, one hydrogen atom, and one oxygen atom are joined together to form the aldehyde group (-CHO). Any organic compound in which a carbon atom has a double bond with an oxygen atom, a single bond with a hydrogen atom, and a single bond with another atom or group of atoms (designated R in general chemical formulas and structure diagrams) is called an aldehyde.
所有醛都含有羰基,它是碳和氧之间的双键。
醛具有通式C n H 2n O ,其中 n 是一个分子中的碳原子数。许多醛具有令人愉悦的气味,它们是通过从醇中脱氢(除去氢)产生的,这就是术语“醛”的来源。两种简单的醛是甲醛 HCHO,也称为甲醛和乙醛 CH 3 CHO,也称为乙醛。
酮组
One carbon atom and one oxygen atom make up the ketone group (-CO-). The presence of a carbonyl group, in which the carbon atom is covalently bonded to an oxygen atom, distinguishes ketone from other organic molecules. The carbon atom is joined by a double bond to the oxygen atom. The alkyl groups or hydrocarbon radicals (R) form the remaining two bonds.
由于酮基总是存在于碳链的中间,因此酮的分子中必须至少有三个碳原子,一个酮基碳原子,两侧有两个碳原子。少于三个碳原子的酮实际上是不可能的。
酮具有通式C n H 2n O ,其中 n 是一个分子中的碳原子数。最简单的酮是丙酮 CH 3 COCH 3 ,也称为丙酮。酮分子的生理作用是显着的。它们可以存在于各种糖以及药物化学品中,例如天然和合成类固醇激素。抗炎药可的松在其分子中含有三个酮基。
羧酸组
A carboxylic acid is an organic molecule with a carbon (C) atom double-bonded to an oxygen (O) atom and a single-bonded hydroxyl group (OH). The carbon atom is linked to a hydrogen (H) atom or another univalent combining group by a fourth bond. The carbonyl (C=O) and hydroxyl (-OH) groups make up the carboxyl (-COOH) group.
羧酸,通常称为有机酸,是包含羧酸基团的有机分子。羧酸有时被称为链烷酸。
同系羧酸具有通式R-COOH ,其中R代表烷基。乙酸 CH 3 COOH 也称为乙酸,是最常见的羧酸。酸度是羧酸最重要的化学性质。它们比其他具有羟基的有机化合物酸性更强,但比众所周知的无机酸酸性更低。
Alkene and Alkyne groups
The alkene group is a carbon-carbon double bond. The alkene group is present in ethene and propene among others. The compounds containing the alkene group are known as alkenes. The homologous series of alkenes have the general formula CnH2n, where n is the number of carbon atoms in one molecule.
The alkyne group is a carbon-carbon triple bond. The alkyne group is present in ethyne, and propyne among others. The compounds containing the alkyne group are known as alkynes. The homologous series of alkynes have the general formula CnH2n-2, where n is the number of carbon atoms in one molecule.
示例问题
问题 1:写出4 个碳原子的醇基的分子式。
回答:
The molecular formula for the alcohol group is CnH2n+1OH. If there are 4 carbon atoms then n=4, this means C4H2(4)+1OH or C4H9OH. So the required molecular formula is C4H9OH
问题2:化合物C 2 H 4 O 可以是酮基吗?
回答:
A ketone must have at least three carbon atoms in its molecules, one ketone group carbon atom, and two carbon atoms on both sides. Ketones with less than three carbon atoms are not really possible. In the given compound, we have 2 carbon atoms, so it is not a ketone group.
问题3:从丁烷衍生的醛的分子式是什么?
回答:
Aldehydes have the general molecular formula CnH2nO, where n is the number of carbon atoms in one molecule. Since butane C4H10 has 4 carbon atoms, so n=4, this means C4H2(4)O or C4H8O. Hence the molecular formula of aldehyde which is derived from butane is C4H8O.
问题 4:确定化合物 C 3 H 8 O 中存在的官能团。
回答:
In the given compound C3H8O, the number of carbon atoms is 3, so n=3. First check if it satisfies the molecular formula of alcohol, aldehyde, ketone, or carboxylic acids. Since it has only one oxygen atom, so it cannot be a carboxylic group. Alcohol has the general molecular formula CnH2n+1OH, where n is the number of carbon atoms in one molecule. Put n=3 in this formula, we get C3H2(3)+1OH or C3H7OH or C3H8O which matches the given compound. So the given compound have alcohol as its functional group.
问题 5:写出含有 5 个碳原子的烯基和炔基的分子式。
回答:
Given that there are 5 carbon atoms, so n=5. Alkenes have the general formula CnH2n, where n is the number of carbon atoms in one molecule. Put n=5 in this formula, C5H2(5) or C5H10.
Alkynes have the general formula CnH2n-2, where n is the number of carbon atoms in one molecule. Put n=5 in this formula, so C5H8 or C5H8.
Hence the molecular formula for the alkene group is C5H10 and the alkyne group is C5H8.