Of 2-bromo-3-methylbutane , 2-chlorobutane , 2-chloro-2-methylpropane, which haloalkanes will give 3,4-dimethylhexane when treated with sodium metal (Wurtz reaction)? Write the reaction equation?

Question

Ruby Allen · Accepted Answer

Start with 2-chlorobutane.

Writing down the equation for each reactant and determining which one yields the desired product would be one way to solve this problem. Often, performing a retrosynthesis is simpler. That is, we determine what the starting materials must be by working backwards from the products. Wurtz synthesis is #"R-X + 2Na" → "R-R + 2NaX"# Thus, we could compose #"R-R" ⇒ "R-X + X-R"# (⇒ means "implies" or "can be made from"). Regarding your issue, we could write #"CH"_3"CH"_2"CH(CH"_3")-CH(CH"_3")CH"_2"CH"_3 ⇒ "CH"_3"CH"_2"CH(CH"_3")-X" + "X-CH(CH"_3")CH"_2"CH"_3# If you look at the list of starting materials, yours must be #"CH"_3"CH"_2"CH(CH"_3")-Cl"#, 2-chlorobutane. Next, the reaction's equation is #"CH"_3"CH"_2"CH(CH"_3")-Br" + "2Na" + "Br-CH(CH"_3")CH"_2"CH"_3 → "CH"_3"CH"_2"CH(CH"_3)"-CH(CH"_3")CH"_2"CH"_3#

Brooklyn Barber · Answer

undefined 2-bromo-3-methylbutane and 2-chlorobutane.

Equations:
$$ \text{2-bromo-3-methylbutane} + 2 \text{Na} \rightarrow \text{3,4-dimethylhexane} + \text{2NaBr} $$
$$ \text{2-chlorobutane} + 2 \text{Na} \rightarrow \text{3,4-dimethylhexane} + \text{2NaCl} $$