[Davidmb65]

Hi,  I teach on the new BTEC National Level 3 Applied Science and was hoping somebody could help me.  In the Organic Chemistry unit the students are asked about benzene reactions - particularly the addition reactions with hydrogen and chlorine and their mechanisms.  I cannot find any information on this on-line and bearing in mind this is a Level 3 course was wondering if anyone could help.
Thanks

[chenbeier]

Check here:

https://www.chemguide.co.uk/organicprops/arenes/halogenation.html


https://chem-guide.blogspot.com/2010/04/chemical-properties-of-benzene.html

https://www.chemguide.co.uk/basicorg/bonding/benzene1.html#top

[Davidmb65]

Hi, Thanks for highlighting some links related to the chlorination of benzene, however none of the chemguide links discuss the addition mechanism of the complete chlorination of benzene to form hexachlorocyclohexane, they do refer to the balanced equation for this reaction and they do discuss the electrophilic substitution process whereby one chlorine atom substitutes for one hydrogen atom.  I was really wanting to find out about the addition mechanism.  Thanks

[spirochete]

If you don't need a reference, it seems reasonable that it would be a radical mechanism given the fact that it requires light. Probably they don't talk about it in most lower level texts because radical addition of halogens to C=C pi bonds tends to be completely ignored. Probably because it will overwhelm the student. Most texts will cover polar addition or substitution where X2 acts like an electrophile, and radical substitution where a hydrogen is replaced on an alkane. Radical addition to alkenes or aromatic rings is arbitrarily ignored as a possibility.