同分异构现象的存在是有机物种类繁多的重要原因,因此,分析和判断同分异构体的种类也就成为有机化学的一大特点。作为高考命题的热点之一,这类试题是考查学生空间想像能力和有序思维能力的重要手段。“等效氢法”是判断一元取代物同分异构体数目的重要方法。等效氢是指在有机物分子中处于相同环境的氢原子。烃的一元取代物数目的确定,实质上是看处于环境不同的氢原子数目,因此判 The existence of the phenomenon of isomerism is an important reason for the wide variety of organic compounds. Therefore, the analysis and judgment of isomers also become a major feature of organic chemistry. As one of the hot topics of college entrance examination proposition, this kind of exam questions is an important means to examine students’ ability of imagination and orderly thinking. “Equivalent hydrogen method ” is an important method to determine the number of isomers of a single substitution. Equivalent hydrogen refers to hydrogen atoms that are in the same environment in organic molecules. The determination of the number of mono-substituted hydrocarbons is essentially based on the number of hydrogen atoms that are in different environments and therefore