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acylation catayst for esters
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ghostwriter
science forum beginner


Joined: 07 Jun 2005
Posts: 19

PostPosted: Mon Jan 16, 2006 5:21 pm    Post subject: acylation catayst for esters Reply with quote

I am currently doing a acylation of a phenoxide. The other reactant is
a HIGHLY sterically hindered ester. That of course is the reason that
it is being done to phenoxide rather than phenol.

Are their any cataysts out there that might stabilize the ether side of
the ester to speed the leaving? Normal a metalic lewis acid would be
(FeBr3, etc) used but I dont know if the complex with the ester will
form in the high pH necessary to form the phenoxide.

Any thoughts appreciated

Ghostwriter
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Uncle Al
science forum Guru


Joined: 24 Mar 2005
Posts: 1226

PostPosted: Tue Jan 17, 2006 2:17 am    Post subject: Re: acylation catayst for esters Reply with quote

ghostwriter wrote:
Quote:

I am currently doing a acylation of a phenoxide. The other reactant is
a HIGHLY sterically hindered ester. That of course is the reason that
it is being done to phenoxide rather than phenol.

Are their any cataysts out there that might stabilize the ether side of
the ester to speed the leaving? Normal a metalic lewis acid would be
(FeBr3, etc) used but I dont know if the complex with the ester will
form in the high pH necessary to form the phenoxide.

Any thoughts appreciated

Hindered ester displaced by phenoxide? You gotta be kidding.

Ag(I) salt of the phenoxide, acyl halide, no light. FeX3 will oxidize
the phenoxide. Heck, Ag(I) may oxidize the phenoxide - then Cu(I) or
Tl(1). Will the acyl form a stable [BF4]- or [PF6]- salt of the
acylium ion? No oxygen allowed.

You want a solvent that will not solubilize metathesis MX ppt.

--
Uncle Al
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http://www.mazepath.com/uncleal/qz.pdf
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ghostwriter
science forum beginner


Joined: 07 Jun 2005
Posts: 19

PostPosted: Tue Jan 17, 2006 4:16 pm    Post subject: Re: acylation catayst for esters Reply with quote

Uncle Al wrote:
Quote:
ghostwriter wrote:

I am currently doing a acylation of a phenoxide. The other reactant is
a HIGHLY sterically hindered ester. That of course is the reason that
it is being done to phenoxide rather than phenol.

Are their any cataysts out there that might stabilize the ether side of
the ester to speed the leaving? Normal a metalic lewis acid would be
(FeBr3, etc) used but I dont know if the complex with the ester will
form in the high pH necessary to form the phenoxide.

Any thoughts appreciated

Hindered ester displaced by phenoxide? You gotta be kidding.

The reaction proceeds fine, just slowly. It doesnt start out too
hindered but since it is a polymer it gets that way very fast. It is
my assumtion that the reaction only proceeds partway and we could get
better performance if we could force it further.

Quote:
Ag(I) salt of the phenoxide, acyl halide, no light. FeX3 will oxidize
the phenoxide. Heck, Ag(I) may oxidize the phenoxide - then Cu(I) or
Tl(1). Will the acyl form a stable [BF4]- or [PF6]- salt of the
acylium ion? No oxygen allowed.

The acyl halide is not really necessary as I am just bridging between
two modified phenoxides and dont really require the carbonyl
functionality. Industrial scale so sodium/potassium/calcium are the
only real contenders for the phenoxide salt. Perhaps a long chain
poly-alkyl halide.

Quote:
You want a solvent that will not solubilize metathesis MX ppt.

Thanks for the suggestions.

Ghostwriter
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