[pizza1512]

Hi all,

I was looking at some reaction mechanism and have a few questions! Here they are:

Q1. When you attempt nitration with a benzene ring, i.e. using conc HNO₃ and conc H₂SO₄, you add on a NO₂ group. But when you have nitration with methylbenzene, is there anything preventing them forming onto the 2nd, 3rd or 4th carbon i.e. forming ortho-, meta- and para- derivatives, or is that dependant on the most stable form?

Q2. With 1-methyl,4-aminobenzene, apparently if you add sodium nitrite and conc. sulphuric acid, you produce 1-methyl,4-(a N₂⁺ group which I don't actually know how to name)benzene! Can anyone certify what actually happens in this mechanism?

Q3. Linking on to the product of 2., apparently if you use copper cyanide on that, you get 1-methyl,4-cyanobenzene. Is this a electrophilic substitution, and how would that mechanism work? I'm sure the delocalisation of the electron ring system reduces the power of the N₂⁺ group in Q2, but how would that allow the cyanide group to react?

Q4. Last and final question, linking on to 1-methyl,4-cyanobenzene, apparently you get 1-methyl,4-methylamide when you use LiAlH₄ and H₂O. Can someone show me how the mechanism works for that also? I'm not quite sure how the CH₂ group appears from, and how does having water *delete me*

Cheers! Who says chemistry isn't mindbogging? 

[nj_bartel]

This above my level of knowledge, but for Q1, I'd assume it has to do with resonance structures, and the positions you see the NO₂ groups adding are the only reactive positions (due to resonance forms similar to those seen in phenoxide or phenylmethylium)

[ARGOS++]

Dear pizza1512;

Let’s give for your start the Links for Q1.)  and  Q2.):

Q1.):  http://www.mhhe.com/physsci/chemistry/carey/student/olc/ch12substituenteffects.html

Q2.): http://www.chemgapedia.de/vsengine/vlu/vsc/en/ch/12/oc/vlu_organik/aromaten/reaktionen/ar_se_beispiele.vlu/Page/vsc/en/ch/12/oc/aromaten/reaktionen/ar_se/diazotierung/diazotierung.vscml.html

Sublinks may also be a help for other questions.
Good Luck!
                    ARGOS⁺⁺