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A-Level Reactions and tests for aldehydes and ketones: worked solution
2 marks. Full working, one step per line.
Question
Benzaldehyde, C6H5CHO, is an organic substance well known for its almond-like smell. It can react to give several different products. In Reaction I, benzaldehyde (C6H5CHO) is turned into phenylmethanol (C6H5CH2OH). In Reaction II, benzaldehyde is turned into nitrobenzaldehyde (the benzaldehyde ring now carrying an NO2 substituent). Give the type of reaction taking place in each case. Reaction I: Reaction II:
Worked answer
Reaction I: CHO (aldehyde) is converted to CH2OH (alcohol). Oxygen count decreases / hydrogen is added to the C=O, so this is a reduction. Reaction II: an H on the benzene ring is replaced by an NO2 group. This is an electrophilic substitution (nitration).
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This question is part of A-Level Reactions and tests for aldehydes and ketones, in A-Level H2 Chemistry.