同分异构现象在有机化合物中普遍存在,它是有机化合物数目繁多的原因之一。在整个教材所讨论的各类化合物中都存在着同分异构现象,因此,对于这一重要概念,我们必须牢固掌握。同分异构现象,顾名思义,它是化合物具有相同的分子式而结构不同的一种现象。但就有机化合物的结构来说,有三个不同层次,即构造、构型和构象。通过对教材第一至第七章的学习,我们知道,在分子结构的三个层次中都存在着同分异构现象。譬加,很多类化合物都存在着碳链异构和位置异构,此外,在不同类化合物之间存在着类别异构;以及有时还存在着可相互转变的动态互变异构等。这些异构 Isomerism is common in organic compounds and it is one of the reasons for the large number of organic compounds. There are isomeric phenomena in all the compounds discussed in the entire textbook. Therefore, we must firmly grasp this important concept. Isomerism, as the name implies, is a phenomenon in which compounds have the same molecular formula and different structures. However, there are three different levels of structure of organic compounds, namely, structure, configuration and conformation. By learning the first to seventh chapters of the textbook, we know that there are isomeric phenomena in the three levels of molecular structure. In addition, there are carbon chain isomers and positional isomers in many types of compounds. In addition, there are categorical isomers among different types of compounds, and there are sometimes dynamic tautomerism that can be mutually converted. These heterogeneous