(4) ? (One of adjacent, middle and paired is enough)
Test analysis: (1) ethanol contains hydroxyl groups, which can be catalytically oxidized to acetaldehyde, so the chemical equation of the reaction is.
(2) Acetic acid is generated by continuous oxidation of acetaldehyde, and then B is acetic acid. C is the hydrolysis product of halogenated hydrocarbon, so C is benzyl alcohol. Benzyl alcohol reacts with acetic acid to produce phenylmethyl acetate, and esterification is also a substitution reaction.
(3) Both the reactions ① and ③ generate water, and the atomic utilization rate can't reach 100%. In reaction 2, the reaction product of acetaldehyde and oxygen is only acetic acid, and the atomic utilization rate reaches 100%, which meets the requirements of green chemistry.
(4) The aromatic compounds of benzyl alcohol isomers are phenols and ethers, so the possible structural formula is.
Comments: This question is a common question in the college entrance examination and belongs to a moderately difficult question. The examination questions are close to the college entrance examination, which is basic. While paying attention to the consolidation and training of students' basic knowledge, we also pay attention to the cultivation of students' ability and the guidance and training of problem-solving methods. It is conducive to improving students' ability to take exams and answer questions, and also to cultivating students' knowledge transfer ability. The key to this question is to remember the structure and properties of common functional groups and their mutual transformation, and then use them flexibly in combination with the meaning of the question.