有机化学绪论

（程青辰有机化学学习笔记）

有机化学发展

1806年，瑞典贝采利乌斯首次提出有机化学一词。当时，许多化学家相信这样的观点：只有生物体内才存在有机化合物，无机化合物存在于矿藏之中。（当时称之为生命力学说）

Organicchemistry develops

In 1806, theterm organic chemistry was first proposed by bezelius in Sweden. At the time,many chemists believed in the idea that only organic compounds exist in livingorganisms, and inorganic compounds exist in mineral deposits. (It was calledthe theory of life force at the time).

1828年，德国化学家维勒通过加热的方法使得氰酸铵（无机物）转化为尿素（有机物）；1845年，德国科学家科尔贝采用二氧化碳、水、氯气合成了醋酸；1854年，法国化学家波塞洛合成了脂肪。

人工合成有机物的事实对生命力学说冲击巨大。

所以，有机物质存在于生命体中这种说法本质上是错误的。但是由于有机化学和有机化合物的说法由来已久，沿袭至今仍被广泛接受。

In 1828, the German chemist Wheelerconverted ammonium cyanate (inorganic matter) into urea (organic matter) byheating;in1845, german scientist Corbysynthesized acetic acid using carbon dioxide, water and chlorine;in1854, the French chemist Porcello synthesized fat.

The fact that organic matter is syntheticallyhas a huge impact on the theory of vitality.

Therefore, the idea that organic matterexists in living organisms is inherently wrong. However, because the terms oforganic chemistry and organic compounds have been around for a long time, theyare still widely accepted today.

18世纪，是一个科学发现和科学探索飞速和累积的阶段。

1830年，德国化学家李比希发展了碳氢分析法；1833年，法国化学家杜马建立了氮分析法；1848年，法国化学家巴斯德铠庫勒提出四价碳概念。20世纪60年代，化学家伍德沃德和霍夫曼研究了电环化反应、环加成反应等，提出了分子轨道对称守恒原理。

The 18thcentury was a period of rapid and cumulative scientific discovery andexploration.

In 1830, theGerman chemist Liebig developed the hydrocarbon analysis method; in 1833, the French chemist Dumas established the nitrogen analysis method; in 1848, the French chemist Pasteur Kökuller proposed the concept oftetravalent carbon. In the1960s, chemistsWoodward and Hoffman studied electrocyclization reactions and ring additionreactions, and proposed the principle of conservation of molecular orbitalsymmetry.

有机化学有机化合物化学键

化学键基本分三大类：共价键、离子键、金属键。

价键理论：20世纪初，价键理论和分子轨道理论互为补充，对共价键的本质和形成进行了较为规范合理的解释。

价键理论又称为电子配对。通过电子配对公用，使得体系能量降低，从而形成较为稳定的共价键。

在电子配对公用的过程中，需要满足三个必要条件：

1. 配对电子自旋方向相反；
2. 共价键具有饱和性:一个未成对电子只能配对一次；
3. 电子配对只有沿着电子云密度大的方向进行，才能得到有效重叠。

OrganicChemistryChemical bonds of organic compounds

Chemical bonds are basically divided intothree categories: covalent bonds, ionic bonds, and metal bonds.

Valence bondtheory: At the beginning ofthe 20thcentury, valence bond theory and molecular orbital theory complemented eachother, and the nature and formation of covalent bonds were explained morestandardized and reasonable.

Valence bond theory is also known aselectronic pairing. Through the electronic pairing, the energy of the system isreduced, thereby forming a relatively stable covalent bond.

In the process of electronic pairing utility,three necessary conditions need to be met:

1. Paired electron spinsin opposite directions;
2. Covalent bonds aresaturated:an unpaired electron can only bepaired once;
3. Electron pairing canonly be effectively overlapped if it is carried out in the direction of highelectron cloud density.

杂化轨道理论

价键理论在解释原子的价键数目以及分子空间结构却遇到了挑战。化学家鲍林等人提出了杂化轨道理论。杂化轨道理论主要容有以下几点:

1. 在同一个原子中，几个能量相近的不同类型的原子轨道可以进行线性组合，重新分配能量，确定空间方向。杂化后的电子云向一个方向集中；
2. 杂化后的轨道更加有利于原子轨道之间的最大程度重叠，所以杂化轨道比原轨道成键能力更强；
3. 杂化后的轨道之间在空间取得最大夹角分布，所以相互间的排斥能最小。

Hybrid orbital theory

Valence bond theory has encountered challenges in explaining the numberof valence bonds of atoms and the structure of molecular space. Chemist Paulinget al. proposed the hybrid orbital theory. Hybrid orbital theory mainlycontains the following points:

1. In the same atom,several different types of atomic orbitals with similar energies can becombined linearly, redistributing energy and determining the spatialorientation. The hybridized electron cloud is concentrated in one direction;
2. Hybridized orbitalsare more conducive to maximum overlap between atomic orbitals, so hybridorbitals have a stronger bonding ability than the original orbitals;
3. The hybridizedorbitals achieve the largest diagonal distribution in space, so the mutualrepulsion can be minimal.

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