Which of the following Grignard reagents is commonly used for the estimation of active hydrogen in a compound?

Options

A. `C_(6)H_(5)MgI`
B. `C_(6)H_(11)MgI`
C. `CH_(3)I`
D. `C_(2)H_(5)MgI`

Answer

C

Explanation

An active `H` atom is one which is joined to an electronegative atoms such as `O,N or S`. When such compounds react with a `GR`, the alkyl group is converted into the alkane:
`underset(1 mol)(RMgX)overset(HZ)rarrunderset(1 mol)(RH)`
Since reactions with compounds containing an active `H` atom result in the quantitative yield of hydrocarbon, this type of reaction is valuable for the determination of the number of active `H` atoms in a compound. The process is known as the Zerewitinoff active hydrogen determination.
Methyl magnesium iodide is normally used as the `GR`. The methane gas which is liberated is measured ( by volume). According to the equation given earlier, one molecule of `CH_(4)` is equivalent to one active `H` atom.