Compound 'A' with molecular formula C_(4)H_(9)Bris treated with aq. KOH solution. The rate of this reaction depends upon the concentration of the compound 'A' only. When another optically active isomer 'B' of this compound was treated with aq. KOH solution, the rate of reaction was found to be dependent on concentration of compound and KOH both. (i) Write down the structural formula of both compounds 'A' and 'B'. (ii) Out of these two compounds, which one will be converted to the product with inverted configuration.

Compound 'A' with molecular formula C_(4)H_(9)Bris treated with aq. KO

1.	Compound 'A' with molecular formula C_(4)H_(9)Bris treated with aq. KOH solution. The rate of this reaction depends upon the concentration of the compound 'A' only. When another optically active isomer 'B' of this compound was treated with aq. KOH solution, the rate of reaction was found to be dependent on concentration of compound and KOH both. (i) Write down the structural formula of both compounds 'A' and 'B'. (ii) Out of these two compounds, which one will be converted to the product with inverted configuration.
Answer» Solution :(i) Compound `A = CH_(3) - underset(BR)underset(\|)overset(CH_(3))overset(\|)C - CH_(3) "Compound " B = CH_(3) - CH_(2) - underset(Br)underset(\|)CH - CH_(3) ` Tert, alkyl halides react by `S_(N)1`mechanism. The rate depends upon the concentration of alkyl halide only. B MUST be secondary alkyl halide because primary isomer is not optically active. Here `S_(N)2`mechanism takes place. (ii) Compound B, because in `S_(N)2`mechanism, inversion of configuration takes place.