Sauron
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TCT (Cyanuric Chloride)
I have mentioned this reagent in a few threads but just now found the reference I was looking for, concerning use of CC to convert acids to acid
chlorides
Venkamaran and Wagle, Tetrahedron Letters 32, 3037 (1979)
3 hours stirring at 20-30 C with the acid in acetone in presence of TEA gives acetyl chloride from acetic acid 87% yield, benzoyl chloride from
benzoic acid 83%. Succinic and oxalic acids 55% and 52% respectively. No reaction with malonic acid.
Other references indicate CC with NaBH4 reduces acids to alcohols. CC converts alcohols to alkyl chlorides or to iodides. CC dehydrates oximes and
amides to nitriles.
The inexpensive and simple route to acetyl chloride and hence to acetic anhydride is good news.
The same to oxalyl chloride, an expensive but very useful reagent, is also good news.
Acros for example sells 250g CC for <$13 US. CC is mass produced by companies like Lonza as part of their HCN platform, it is used as a feedstock
for manufacture of agro chemicals.
There are three reactive chlorines on this compund. By simply refluxing a large excess of acetic acid with CC, cyanuric acid ppts out quantitatively,
acetyl chloride (3 mols for every mol of CC) is fractionated from the acetic acid (there's about a 40 C difference in the b.p.'s).
[Edited on 17-7-2007 by Sauron]
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solo
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Reference Information
Mild reduction of carboxylic acids to alcohols using cyanuric chloride and sodium borohydride
Massimo Falorni, Andrea Porcheddu and Maurizio Taddei
Tetrahedron Letters, Volume 40, Issue 23, 4 June 1999, Pages 4395-4396
Abstract
Several carboxylic acids, including N-Boo, N-Cbz and N-Fmoe amino acids were reduced to the corresponding alcohols by activation of the carboxy
function with cyanuric chloride and N-methylmorpholine followed by reduction with aqueous sodium borohydride.
Attachment: Mild reduction of carboxylic acids to alcohols using cyanuric chloride and sodium borohydride.pdf (125kB)
This file has been downloaded 768 times
It's better to die on your feet, than live on your knees....Emiliano Zapata.
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Sauron
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Well done (medium rare anyway.)
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Isomeric_Fred
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sorry to pull this up after such a long time, but the preperations you noted Sauron are not in the article.. where did u take those prep info from?
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Sauron
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I have edited the first post and corrected the reference. Thanks for pointing out the error.
Anyway here is a scan
A few comments
Ref.6 (Senier) reports that the dry distillation of TCT and sodium acetate gives a poor yield of AcCl, but works very well for TCT and sodium benzoate
to give benzoyl chloride.
However the price of sodium benzoate is about same as benzoyl chloride.
Ref. 7 I have not been able to obtain but it appears to just be a suggestion for a possible preparation rather than a report of one.
In general this Tet.Lett. article is weak on workup details. The authors attempted to cover a very broad range, from low MW monocarboxylic acid to
dicarboxylic acids to fatty acids to amino acids and peptides.
Clearly given the broad range of yields, one will often be left with a mix of reacted and unreacted TCT; the carboxylic acid and its acyl chloride;
TEA ; acetone; etc. and the workup may be a wee bit complex in some cases.
[Edited on 17-7-2007 by Sauron]
Attachment: tetlett32_3079.pdf (953kB)
This file has been downloaded 2021 times
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chemrox
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bromine?
In the past several weeks I've pulled a couple of hundred articles off of JACS and haven't found a decent way to save/organize them. That is said
because during an earlier thread on this subject I seem to have encountered a procedure for making acyl Cl's from acids using TCT but Br2 was also
used. I'm still looking for the written information .. don't know what role Br2 plays and whether Br-succinamide could be used in place. (Am paying
exhorbitantly to get Br2 locally as shipping it is even worse. In the US, Br2 has to go by itself! I've used Br2 many times in the past and can't
understand the excessive cautions.)
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Sauron
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I am familiar with the process to make alkyl bromides from TCT/DMF adduct in presence of KBr and a similar route to alkyl iodides with KI.
I don't recall anything about acyl bromides.
You can prepare TBrT (cyanuric bromide) and that will almost certainly get you acyl bromides.
I do recall that oxalyl chloride under appropriate conditions as detailed by Roger Adams and coworkers in JACS c.1916-1920 can be used to prepare acyl
bromides via oxalyl bromide.
But that is a totally different reagent, and a lot costlier than TCT.
I have same problem about organizing articles, I just lump them by subject into folders that are named by that subject - for example I have a TCT
folder, and a seperate TCCA folder. And a third for the other trihalotriazines. Then if I need to find something I have only the relatively small
number of closely related files to browse, usually they are still named the way ACS did it.
[Edited on 18-7-2007 by Sauron]
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