[Rutherford]

Can someone rationalize the two conversions as I see them for the first time?

[Babcock_Hall]

In the first reaction, which carbon is partially positively charged, and which one is partially negatively charged?

[discodermolide]

Have a look here, http://www.chemguide.co.uk/organicprops/haloalkanes/grignard.html

and here for the second part
http://www.chemtube3d.com/Carbenes-MethylationCarboxylicAcidDiazomethane.html

[Rutherford]

Everything clear. I suppose that an alternative way for the 2nd reaction would be esterification. Thanks again.

[Rutherford]

I got another quick question related to this problem: Why is it better to produce 4-chlorobenzoic acid from chlorobenzene the way that is listed here, than using Friedel-C. alkylation and then oxidation?

[discodermolide]

The Grignard reaction is much more efficient.
Chlorine is a para director as far as I remember. Using an FC reaction will give mixtures.

[Rutherford]

It has to be so that the Grignard reaction work and I found on wikkipedia: "Halogens are ortho/para directors, since they possess an unshared pair of electrons."

[discodermolide]

I have made this Grignard from 4-Chlorobromo benzene and reacted it with CO₂, it is a great reaction.