[adamalt]

  How would you prepare the following from methyl pyridines:
  a) Vitamin naicin
  b) 3-pyridine carboxylic acid
  c) 4-pyridnecarboxylic acid hydrazine

[sjb]

I thought a) niacin (note the spelling) was b) pyridine-3-carboxylic acid? Anyway, consider the notes in other topics here, like at http://www.chemicalforums.com/index.php?topic=23611.0, perhaps.

As to 4-pyridnecarboxylic acid hydrazine I'm not sure what structure you mean. Could you post a gif, or SMILES or similar to show what compound you mean?

S

[adamalt]

4-pyridinecarboxylic acid hydrazine is
 pyridine ring with O and NH NH2 on position 4

[AWK]

a) Vitamin naicin
  b) 3-pyridine carboxylic acid
  c) 4-pyridnecarboxylic acid hydrazine

a) 3-pyridine carboxylic acid amide
  c) 4-pyridnecarboxylic acid hydrazide

[sjb]

4-pyridinecarboxylic acid hydrazine is
 pyridine ring with O and NH NH2 on position 4

So you mean like "unknown.gif", in my uploads?

If you mean 4-pyridinecarboxylic acid hydrazide ("Isoniazide.gif") bear in mind there's a carbonyl there not just an ether as your description indicates. How to do it? methyl -> acid as per previous oxidations or SeO₂, then probably acid chloride and hydrazine (careful)

a) Vitamin naicin
  b) 3-pyridine carboxylic acid
  c) 4-pyridnecarboxylic acid hydrazine

a) 3-pyridine carboxylic acid amide
 c) 4-pyridnecarboxylic acid hydrazide

Hmm, seems there's a bit of confusion. Wikipedia suggests niacin is the free acid (http://en.wikipedia.org/w/index.php?title=Niacin&oldid=195529696, and not just in the English pages), which is what my initial comments were based on, however Joule and Mills (http://www.amazon.co.uk/Heterocyclic-Chemistry-John-Joule/dp/0632054530/ref=sr_1_3?ie=UTF8&s=books&qid=1204555902&sr=8-3) refer to Niacin as the amide, as per AWK's suggestion (which I thought was nicotinamide).

I guess the two are fairly interconvertible in vivo?

S

[AWK]

Our bodies can synthesize nicotinamide from nicotinic acid hence in fact both compounds are called (unfortunatekly) niacin in diet supplement. Nicotinamide is also called witamin PP where nicotinic acid  - witamin B3

[adamalt]

 The unkown gif make sence but how do you put hydrazine in the 4 position and how do you change the methyl group in the 3rd position to =O-OH I guess there must be anyway to do it.

[sjb]

Aromatic methyl groups can be oxidized to carboxylic acids using KMnO₄ under basic conditions (I think it's basic anyway).

I will have a think about 4-methylpyridine to what I have called Unknown.gif, as somehow you'll need to displace that methyl group. Something like 4-methylpyridine -> isonicotinic acid (4-pyridinecarboxylic acid)-> aldehyde (possibly via the alcohol) -> decarbonylation (back to pyridine itself) -> chorination -> displacement? This seems very long winded...

S