Question

An alkyl halide reacts with a group 14 element Y at 570 K with Cu as catalyst and produces a dialkyl chloro compound Z. The compound Z on hydrolysis gives another compound which is a strong water repellent and quite inert chemically. The dioxide of Y is acidic in nature. The alkyl halide can also be obtained from methane after monosubstitution. Identify Y and Z.
(A) Y = Si and Z = $ {(C{H_3})_2}SiC{l_2} $
(B) Y = Si and Z = $ C{H_3}Cl $
(C) Y = C and Z = $ SiC{l_4} $
(D) Y = Si and Z = $ CC{l_4} $

Answer 1

Hint: Group fourteen elements include carbon, silicon, germanium, tin, lead and flerovium. So, compound Y will be among these 6 elements only. Alkyl halides are the compounds in which hydrogen atoms are replaced by a halogen group.

Complete Step by step solution:
Methyl chloride is obtained after monosubstitution of methane. Hence the alkyl halide which reacts with Y is methyl chloride.
Methyl chloride reacts with silicon in the presence of copper as a catalyst to form mono, di and tri methyl chloro silanes and tetra methyl silane. The reaction that takes place is as follows,
 $ C{H_3}Cl + Si\xrightarrow{{{\text{Cu powder}}}}C{H_3}SiC{l_3} + {\left( {C{H_3}} \right)_2}SiC{l_2} + {\left( {C{H_3}} \right)_3}SiCl + {\left( {C{H_3}} \right)_4}Si $
The compound Y is silicon as its oxide silica, $ Si{O_2} $ is acidic. As Z is a dialkyl chloro compound, it is dimethyl chloro silane, $ {\left( {C{H_3}} \right)_2}SiC{l_2} $ . On hydrolysis, dimethyl chloro silane produces $ {\left( {C{H_3}} \right)_2}SiO{H_2} $ which is a strong water repellent and quite inert chemically.
Therefore, the correct answer is option A that is Y = Si and Z = $ {(C{H_3})_2}SiC{l_2} $ .

Note:
Silica is a major constituent of sand, glass. Silica is used in cement, construction, ceramics. Silica is mixed with other materials to produce n-type and p-type semiconductors used as transistors. Haloalkanes is the other name for alkyl halides.