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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: sfarr on August 09, 2012, 04:58:03 PM

Title: Tertiary Amide formation from primary amine with formic acid?
Post by: sfarr on August 09, 2012, 04:58:03 PM

I, being only acquainted in organic chemistry, was wondering if it were possible to take a primary amine (RNH2) and use 2 moles of formic acid to make a tertiary amide (RN(COH)2). Is it possible? I'm sure it is. Also, is it possible to reduce those COH groups with Ammonia gas or concentrated solution in order to produce a tertiary amine?

Title: Re: Tertiary Amide formation from primary amine with formic acid?
Post by: discodermolide on August 10, 2012, 01:25:39 AM

Quote from: sfarr on August 09, 2012, 04:58:03 PM

I, being only acquainted in organic chemistry, was wondering if it were possible to take a primary amine (RNH2) and use 2 moles of formic acid to make a tertiary amide (RN(COH)2). Is it possible? I'm sure it is. Also, is it possible to reduce those COH groups with Ammonia gas or concentrated solution in order to produce a tertiary amine?

What you have here is an imide  -CO-N-CO-. Making these is quite easy.
Reduction of amides and amides occurs with a borane, BH₃ at reflux. Ammonia is not a reducing agent in this sense.

Title: Re: Tertiary Amide formation from primary amine with formic acid?
Post by: sfarr on August 11, 2012, 10:01:35 PM

Thank you for the quick response. How is borane made or at least its adducts? Would it be easier to methylate a primary amine twice with trimethyl borate? Or would that over methylate it to form a salt? How reactive is trimethyl borate in the presence of aromatic rings and such?

Title: Re: Tertiary Amide formation from primary amine with formic acid?
Post by: discodermolide on August 12, 2012, 01:17:16 AM

Quote from: sfarr on August 11, 2012, 10:01:35 PM

Thank you for the quick response. How is borane made or at least its adducts? Would it be easier to methylate a primary amine twice with trimethyl borate? Or would that over methylate it to form a salt? How reactive is trimethyl borate in the presence of aromatic rings and such?

You buy the boranes, do not attempt to make them. Amines you methylate with methyl iodide. Trimethylborate is quite reactive, depends on the substituents on the aromatic ring.

Title: Re: Tertiary Amide formation from primary amine with formic acid?
Post by: sfarr on August 12, 2012, 01:27:40 AM

I was just curious. Thanks for the concern though. As for the perborate however, could it be used if the aromatic ring has no substituents? What about if it has another nitrogen or a methoxy group?

Title: Re: Tertiary Amide formation from primary amine with formic acid?
Post by: sfarr on August 12, 2012, 01:46:13 AM

*I mean trimethyl borate.. sorry

Title: Re: Tertiary Amide formation from primary amine with formic acid?
Post by: discodermolide on August 12, 2012, 02:02:26 AM

Quote from: sfarr on August 12, 2012, 01:27:40 AM

I was just curious. Thanks for the concern though. As for the perborate however, could it be used if the aromatic ring has no substituents? What about if it has another nitrogen or a methoxy group?

Boron has a great affinity for nitrogen. I would not use trimethyl borate to methylate an amine.

Title: Re: Tertiary Amide formation from primary amine with formic acid?
Post by: sfarr on August 18, 2012, 02:34:08 AM

I was thinking, what if I mixed trimethyl borate and aqueous ammonia prior to introducing it to the primary amine, so that the trimethyl borate/ammonia species was formed with a negligible to no trimethyl borate remaining.

Title: Re: Tertiary Amide formation from primary amine with formic acid?
Post by: discodermolide on August 18, 2012, 05:21:36 AM

Quote from: sfarr on August 18, 2012, 02:34:08 AM

I was thinking, what if I mixed trimethyl borate and aqueous ammonia prior to introducing it to the primary amine, so that the trimethyl borate/ammonia species was formed with a negligible to no trimethyl borate remaining.

Why make life difficult for yourself, just use an alkyl halide to alkylate the nitrogen.

Title: Re: Tertiary Amide formation from primary amine with formic acid?
Post by: sfarr on August 18, 2012, 02:58:25 PM

Yeah, I know. I'm just trying to find a greener way to methylate the primary amine. Also I don't want an ammonium salt to form.

Title: Re: Tertiary Amide formation from primary amine with formic acid?
Post by: discodermolide on August 18, 2012, 09:31:11 PM

Quote from: sfarr on August 18, 2012, 02:58:25 PM

Yeah, I know. I'm just trying to find a greener way to methylate the primary amine. Also I don't want an ammonium salt to form.

There is no greener way to do this, in fact there is no such thing as green chemistry, only waste reduction.
Avoiding the ammonium salt is difficult.