$\mathrm{CH}_{3}-\mathrm{C} \equiv \mathrm{C} \mathrm{MgBr}$ can be prepared by the reaction of
$\mathrm{CH}_{3}-\mathrm{C} \equiv \mathrm{C} \mathrm{MgBr}$ can be prepared by the reaction of
$\mathrm{CH}_{3}-\mathrm{C}=\mathrm{C}-\mathrm{Br}$ with $\mathrm{MgBr}_{2}$
$\mathrm{CH}_{3}-\mathrm{C} \equiv \mathrm{CH}$ with $\mathrm{MgBr}_{2}$
$\mathrm{CH}_{3}-\mathrm{C} \equiv \mathrm{CH}$ with $\mathrm{KBr}$ and $\mathrm{Mg}$ metal
$\mathrm{CH}_{3}-\mathrm{C} \equiv \mathrm{CH}$ with $\mathrm{CH}_{3} \mathrm{MgBr}$
Solution
$\mathrm{CH}_{3}-\mathrm{C} \equiv \mathrm{CMg}$ Br can be prepared by the reaction of $\mathrm{CH}_{3}-\mathrm{C} \equiv \mathrm{CH}$ with $\mathrm{CH}_{3} \mathrm{MgBr}$.
This method is used in preparation of higher alkynes from lower alkynes. The chemical equation for the formation of $\mathrm{CH}_{3}-\mathrm{C} \equiv \mathrm{CMgBr}$ is given below
$\mathrm{CH}_{3}-\mathrm{C} \equiv \mathrm{CH}+\mathrm{CH}_{3} \mathrm{MgBr} \longrightarrow \mathrm{CH}_{3}-\mathrm{C} \equiv \mathrm{CMg} X$
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