(i) Givean industrial preparation of (a) formaldehyde, (b) acetaldehyde and (c) acetone
(ii) Give the methods by which ethyl alcohol may be converted into acetaldehyde
(iii) How is an aldehyde obtained from an acid chloride?
(iv) Write an equation for making aldehydes by the oxo process.
(v) How is impure acetaldehyde purified? ltbr (vi) How is impure acetone purified?

Explanation

`(a) CH_(3)OH+O_(2)underset(Cu)overset(873K)rarrHCHO`
(b) `HC-=CHunderset(H_(2)SO_(4))overset(HgSO_(4))rarrCH_(3)CHOor H_(2)C=CH_(2)+O_(2)underset(H_(2)O)overset(PdCl_(2),CuCl_(2))rarrCH_(3)CHO" " ("Wacker's process")`
(a) By oxidation with acidified `K_(2)Cr_(2)O_(7)`
(b) By catalytic dehydrogenation-vapours are passed over heated copper at 573K
By Rosenmund's reduction, `ROCl+H_(2)RCHO+CHl`
`R-CH=CH_(2)+CO+H_(2)overset(Co_(2)(CO)_(8))rarrRCH_(2)CH_(2)CHO`
`underset("Impure")(CH_(3))CO+NH_(3)rarrCH_(3)CH(OH)NH_(2)overset(H_(2)SO_(4))rarrunderset(("Pure"))(CH_(3))CHO+NH_(4)HSO_(4)`
`underset("Impure")((CH_(3))_(2)CO+NaHSO_(3)rarr)(CH_(3))_(2)C(OH)SO_(2)ONaoverset(Na_(2)CO_(3))rarrunderset(("Pure"))((CH_(3))_(2)CO`