[AlphaScent]

So I was having a discussion with a colleague about the this type of practical chemistry.  I have never done this nor has he, but we are debating whether one would have to isolate the oxime first and purify or could after an amount of time just add the the acid to complete the conversion.  I believe it is better to isolate since it is most often a solid product. Purify by recrystalization and then treat with acid.  What are your thoughts?  Does anyone have a good procedure for this chemistry ?

[discodermolide]

I have no experimental data. But if you can isolate and purify the intermediate oxime. Then you can make sure it is what you think it is.

[AlphaScent]

Disco,

Yea if I can isolate my product and run NMR that is my best option.  I believe an oxime should be easily isolated and recrystallized.  I would like to try this chemistry.  Don't get to work with nitrogen containing compounds much, if ever.  Pyridine maybe, but that doesnt really count : )

[kriggy]

Im just curious, what kind of chemistry you do? TBH I hardly ever see compounds not containing nitrogen

[AlphaScent]

Kriggy,

I do organic chemistry of natural products and focus on insect pheromones.  The company I work for synthesizes the compounds for attract and kill and monitoring purposes for mostly agricultural customers.  It is total synthesis which is fun.  Small company.  I remembered the rhino beetle pheromone I synthesized about 6 months ago and that utilized the Mannich reaction.  So I guess I lied, I have done amine chemistry.  What about you Kriggy, what kind of chemistry do you do?

[orgopete]

This looks a variant of the adage, an hour in the library can save a week in the lab, and the counter saying, an hour in the lab can save a week in the library.

In industry, chemicals are generally cheaper than labor. If I had a cheap chemical, I'd run a reaction on the scale needed to give what I wanted in one reaction. If it succeeded, I would be ahead of piloting the reaction. If it failed, it would be like a large scale pilot reaction.

In this case, if I had a one step procedure (I presume there are some), I'd just try it with an amount you would not mind even if it failed. If it failed, I'd isolate the intermediate. That would tell you something about why it failed.

[kriggy]

Kriggy,

I do organic chemistry of natural products and focus on insect pheromones.  The company I work for synthesizes the compounds for attract and kill and monitoring purposes for mostly agricultural customers.  It is total synthesis which is fun.  Small company.  I remembered the rhino beetle pheromone I synthesized about 6 months ago and that utilized the Mannich reaction.  So I guess I lied, I have done amine chemistry.  What about you Kriggy, what kind of chemistry do you do?

Sorry If I offended you, I just realized that my qustion must sound bit...weird.. Im just taking sometimes things 100% literally.. Im just a student so the chemistry Im doing is nothinng like total synthesis. Im trying to prepare compound which will serve as an mimic of superoxid dismuthase and  then determine how substitution on it will affect this activity.

[AlphaScent]

No offense at all.

[AlphaScent]

So I consulted a Professor I know and also read up on oximes in Vogel.  According to him (He's been around) oximes were used prior to NMR for characterization of carbonyl compounds.  He basically told me that they are very easy to make and isolating them are quite simple.  Vogel also has a procedure for using oxime derivatives for characterization and is a straight forward procedure.  A day studying indeed is better than a week in the lab.

Furthermore we were then discussing the Beckmann rearrangement as I first mentioned.  The reaction mechanism I wrote I believe is wrong.  It would not produce the formamide derivative (What is the amide equivalent of a formate called??), but the amide.  With the NH2 being teminal, not internal.

Am I correct?  It seems to me that the amide would be more stable than a formamide derivative during the mechanism.

Thanks for listening,

Cheers

[AlphaScent]

Also, I understand that there is a hydrogen on the carbocation that shouldnt be there.  Could not get my drawing program to remove it.

cheers

[Archer]

Furthermore we were What is the amide equivalent of a formate called??), but the amide.  With the NH2 being teminal, not internal.

Carboxamide, I think.

[AlphaScent]

Carboxamide is a general term, and is in fact correct here.  The compound I am referring to -C-N-C=O, terminal like a formate is still just a amide.  My boss says there is no "special term" like a formate ester.  Thanks for the response. 

Any thoughts on which way the Beckmann would proceed, Archer? 

[Archer]

I have made plenty of oximes but never made amides from them, sorry.

I will look into it tomorrow if someone else doesn't get in there first.

[orgopete]

Perhaps someone could check this proposed Beckmann rearrangement. Will it follow this path or will it lose a proton and form a nitrile? A nitrile may give a carboxamide or hydrolyze to a carboxylic acid.

[Archer]

Is this your target molecule



If so would another route be favourable?