[the_angry_fish]

Hello
I'm not sure why it never occurred to me to look for a chemistry forum before now, but, better late than never, I suppose.
I've checked out a few topics, and everyone seemed very helpful, and I'm always getting stuck. I'll also do my best to share my (limited) knowledge where I can 

Anyway, I've just started my honours year in synthetic chemistry, and I'm already having trouble 
I'm trying to add a Boc group to a primary amine, but my yield is quite poor, and I'm not even sure I've got the right product.

The solvent is DCM, and I've added triethylamine (freshly distilled), DMAP (not sure what that was for) and Boc₂O. These were stirred overnight under nitrogen, and then washed with 10% citric acid solution. Then dried (MgSO₄, filtered, and purified on a column. Roto vap to remove solvent, and high vac to get crystals.

If anyone knows or could suggest any ways I could alter this procedure, that would be awesome, since I need a fair amount before I can go any further.

thanks in advance 

Josh

[movies]

Well, those are pretty standard conditions for that reaction.  That happens to be the first reaction that I ran when I got to grad. school.

You might try heating the reaction for a while. 

Are you sure that you (Boc)₂O is good?  Is your CH₂Cl₂ dry?  How soluble do you think your carbamate will be in water?  Maybe you just need a better extraction procedure.  Try TLCing your aqueous phase during workup to look for your product.

Another thing to watch out for is that some polar compounds stick to MgSO₄ pretty fiercely.  You might try Na₂SO₄ as a drying agent instead.  It's much less Lewis acidic.

[the_angry_fish]

Ah, Thankyou
           I'm not too sure about the Boc anhydride, we found it in an unused lab so it may be pretty ancient, it might be worth ordering some more anyway. I think I still have my aqueous phase from my last attempt, so I'll run a TLC of that tomorrow. I've also just been shown how to use the mass spec instrument, so I'll have a look at it on that. I'm guessing the Boc group should be easy to see that way.
I'll try the other things you suggested, too
Thanks again for your help.

[alphahydroxy]

yeah - you'd do well to ensure that your system is dry and the boc anhydride is good... If you don't do this you're going to have trouble with reproducibility...

It's certainly something to bear in mind seeing as you're just starting out - it's all too easy to forget the basic principle of shite in, shite out!  If you do things properly in the first instance and it doesn't work, you can trust yourself that it was the chemistry that didn't work. If you do things cowboy style, you're never too sure...

Oh, and DMAP is used as a nucleophilic catalyst for these type of reaction