Final answer:
To convert ethanal into butane-1, 3-diol, we add a hydrogen to ethanal and react it with lithium aluminum hydride. To convert ethanal into but-2-enal, we add a double bond between the second and third carbon atoms. To convert ethanal into but-2-enoic acid, we oxidize it to form butanoic acid and then remove a carbon dioxide molecule.
Step-by-step explanation:
In order to convert ethanal into the following compounds:
(i) butane-1, 3-diol: We start with ethanal and convert it into butanal by adding a hydrogen. Then, we react butanal with two equivalents of lithium aluminum hydride to obtain butane-1,3-diol.
(ii) but-2-enal: We start with ethanal and convert it into but-2-enal by adding a double bond between the second and third carbon atoms.
(iii) but-2-enoic acid: We start with ethanal and oxidize it to form butanoic acid. Then, we convert butanoic acid into but-2-enoic acid by removing a carbon dioxide molecule.