First of all, we can see that the organic chemistry problems in basic universities are all brominated and have a high boiling point. (1) benzene ring, boiling point is definitely the highest; (3) There is only one carbon, and its boiling point is a little higher than that of natural gas, which is definitely the lowest, even gas; Finally, it is difficult to distinguish between ② and ④. First of all, we can see that ④ contains more carbon than ②, and its boiling point should be higher. At the same time, from the position of substituents, it should be that ② has a large boiling point and is difficult to distinguish. It needs to be judged by experience. In small molecules, the number of alkyl groups has a great influence on the boiling point, which is the main contradiction, and its influence should be given priority, so ④ Choose a larger one, and the specific number of alkyl groups is not the main influence factor.

(1) bromide, boiling point198℃;

② 1- bromopropane, boiling point 71℃;

(3) methyl bromide, boiling point 3.6℃;

④2- bromobutane, boiling point 965438 0.2℃,