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Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: acox1701 on February 23, 2015, 11:44:00 AM

Title: Substitution reaction on a Carboxyl group
Post by: acox1701 on February 23, 2015, 11:44:00 AM

So, I have found, by research, that I can add a carboxyl group to an amorphis or activated carbon by treatment with hydrogen peroxide. So far, so good.

My memory tells me that this is a very useful handle for additional reactions, but I'm having trouble finding how to add a halide at this location, bromine for preference. I found that acetyl acid and phosphorous tribromide together will produce acetyl bromide, but I'm not sure how well it will work with an unidentified carbon mass on the other end.

Can anyone offer me a useful reaction for producing an acyl halide from an unidentified carbon chain with a carboxyl on the end? Many thanks!

Title: Re: Substitution reaction on a Carboxyl group
Post by: TheUnassuming on February 24, 2015, 10:11:50 AM

Not 100% sure I'm understanding you.  What is the carbon chain attached to?

You want to take a carboxylic acid and convert it to an acyl chloride?  There are many good literature sources for how to do this, look at the wiki for acyl chlorides for some good starting points.

How well the reactions work will depend on what other functionalities you have present. 

Title: Re: Substitution reaction on a Carboxyl group
Post by: acox1701 on February 25, 2015, 08:16:39 PM

I have no real idea what's attached to the carbon chain. My carbon source is biomass that has passed through a fast pyrolysis process. It is mostly carbon, some 90%+ by mass (if I remember correctly) which has been treated with H₂O₂. If I'm doing this right, it should add oxygen and carboxyl groups to the surface.

There may be trace amounts of graphene, but it's mostly black carbon powder.

Title: Re: Substitution reaction on a Carboxyl group
Post by: TheUnassuming on February 26, 2015, 07:32:57 AM

How are you planning on monitoring the reaction? 

I think you will have a hard time controlling exactly what gets oxidized, how, and what you get in the end.  This will make getting the acyl halide also difficult. 

Title: Re: Substitution reaction on a Carboxyl group
Post by: acox1701 on February 26, 2015, 06:27:31 PM

I currently have no mechanism for monitoring the reaction. I'm simply planning to follow a procedure laid out in a research paper, and see if it provides good results (there are tests we do on our chem-mod carbon to see if it suits our needs) compared with our current halogination process. (which is, honestly, pathetic)

If it produces comparable results, I might be able to propose better materials and equipment.

Title: Re: Substitution reaction on a Carboxyl group
Post by: kriggy on February 27, 2015, 02:28:51 PM

I think the best start is to have at least some idea what compounds are present in your starting material. It might be difficult but maybe try run your starting material in HPLC-MS and try to identify some components or at least those that are present in higher amounts