在一系列衍变关系中有部分产物已知或衍变条件已知的条件下,用框图或变相框图的形式呈现一系列物质的衍变关系,来推断有机反应中的反应物的问题,能力立意高,综合性比较强,给学生的认知形成一定的障碍.要求熟悉烃及各种衍生物之间的转化关系及转化条件的基础上,还需掌握一定的方法技巧. Under the condition that some of the products have been known or their conditions of evolution are known in a series of evolutionary relationships, the relationship between a series of substances is presented in the form of a block diagram or a modified block diagram to deduce the reactants in the organic reaction, , Comprehensive relatively strong, to the students cognitive form a certain obstacle.Requirements familiar with the conversion of hydrocarbons and various derivatives and conversion conditions, based on the need to master a certain method of skills.