This question is about bees and Brexit

There is concern that neonicotinoid

pesticides are harmful to bees.

Thiamethoxam is one of three

Union $($EU$)$ banned from all outdoor

uses in April $2018.$ When Britain

leaves the EU$,$ this pesticide may

again. People are worried this wi

harm our bee population.

$($a$)$ What is the molecular formula of thiamethoxam?

The synthesis of thiamethoxam begins with glycerol. In the conversion of A to B$,$ two other side

products $(B^{\text{'}}$ and $B^{\text{'}\text{'}})$ can also be formed. $B,B$ isomers. Much less $B^{\text{'}\text{'}}$ is formed than $B^{\text{'}}.$

ubrace$(OHubrace{)}_{OH}excessPOC{l}_3{A}_{C_3{H}_{5}C{l}_3}{?}_{(abase)}^{\text{C}\text{a}\text{O}}{B}^{+}{B}^{\text{'}}+B^{\text{'}\text{'}}$

gycerol

$($b$)$ Draw the structures of $A,B,B^{\text{'}}$ and $B^{\text{'}\text{'}}.$

B reacts with sodium thiocyanate $($ NaSCN $)$ to form $C.$ which can be converted into $D$ upon

treatment with chlorine and carbon tetrachloride.

$($c$)$ Draw a resonance structure of the thiocyanate ion that explains the formation of $C.$

$($d$)$ Draw the electrophile that reacts with guanidine to form $E,$ clearly indicating its shape.

$($e$)$ Draw the structures of E$,$ F$,$ G and H$.$ You only need to draw one tautomer for each

compound

In an alternative synthesis of thiamethoxam, compound $D$ can also be synthesised from

The conversion of $C$ to $D$ occurs via a free radical chain reaction, followed by an elimination.

The chain$-$carrying radical $Z$ adds to the thiocyanate in $C$ to give radical intermediate $V.$

Intermediate $V-$ undergoes cyclisation to give radical intermediate $W*,$ which reacts with

reagent $x$ to form $Y$ and regenerate the chain$-$carrying radical $Z*Y$ then undergoes an

elimination to form $D$

$($i$)$ Draw the structures of radical intermediates $V*$ and $W*,$ and intermediate $Y$

$($j$)$ Identify reagent $x$ and chain$-$carrying radical $Z.$

$($f$)$ Draw the structures of I and intermediate $J$

Intermediate $J$ undergoes dehydration to form $K.$ There are three possible tautomers of $K$

However, as one tautomer is aromatic $($as it has six $$ electrons in a ring like benzene$),$ this

tautomer is far lower in energy than the other two. Hence, at equilibrium this lowest energy

$($g$)$ Draw the structure of the lowest energy tautomer of $K($showing the $$ electrons as

double bonds rather than as a circle$).$

$($h$)$ Draw the structures of $L$ and $M.$