McMurry (Kap. 6,6) - using curved arrows in polar reaction mechanism

Question 1

What are the 4 rules to remember, when using curved arrows in polar reaction mechanisms?

Answer 1

1) Electrons move from a nucleophile source to an electrophile source.

2) The nucleophile can be either negatively charged or neutral

(if negatively charged it becomes neutral after donating electron pair).

(if neutral charged it becomes positively charged after donating electron pair).

3) The electrophile can be either positively charged or neutral.

(if positively charged, it becomes neutral after accepting/binding to a lonepair).

(if neutral, it becomes negatively charged after accepting/binding to a lonepair).

4) The octet rule MUST be followed: s.161. Hydrogen (sur proton) cannot get 4 electrons (must be 2) after polar reaction with mechanism.

Question 2

describe rule 1)

Answer 2

1) Electrons move from a nucleophile source to an electrophile source: the nucleophile should have electron pair available either as lonepair or double bond.

The electrophile must be able to accept the electron pair, by either being positively charged, or by being positively polarized in a functional group (sur proton i en molekyle, eller en carbokation der frastøder halogen og binder til nucleophil).

Question 3

in rule 2) and 3), can you say that the charge on one atom disappears after the polar reaction occur?

Answer 3

No, charge is conserved. Therefore if one of the reactant is (-) charge, the product will be (-) charge, and the same with (+) charge.