Sciencemadness Discussion Board

aryl halide displacement with alkoxide

gardenvariety - 22-1-2010 at 09:28

Is this a named reaction? It's not a Williamson as it is aryl not alkyl, nor an Ullmann as it is not a phenyl-phenyl bond (still Cu catalyzed, though). Anyone know better?

Also I have a question in solvation: some papers run these reactions in the alcohol from which they form the alkoxide, some run it in alcohol plus a substantial volume of alkyl acetate, and some run it in alcohol and DMF. Is it possible (or desirable) to run it in alcohol/DMSO instead of DMF?

I am concerned about DMSO forming the dimsyl anion from the alkoxide, but am not sure of the reaction conditions that favor that. DMF, for instance, doesn't hydrolyze in these conditions (of course these conditions are anhydrous, but hopefully my concern is clear).

Any thoughts? Thanks!

gardenvariety - 22-1-2010 at 09:40

On the second, that Bulletin 105 from Gaylord has the answer:
"The high activity of alkoxide ions in DMSO shows up in their enhanced basicity. The basicity of alkoxides reaches a maximum in DMSO when the mixture is substantially free of hydroxylic material. In this case, the acidity of the alcohols in dilute solutions is about 103 times
that of DMSO so that only a minor equilibrium quantity of the DMSO anion is present (734). The reactivity of the alkoxide ion in DMSO is influenced by the cation and is greater with cesium and with lithium less (606)(1162). The vastly enhanced activity of alkoxide ions in
DMSO over their activity in alcohols is attributed to the absence of alkoxide-solvent hydrogen bonds in DMSO which are present in the hydroxylic solvents (434).
The basicity of alkoxides in DMSO is conveniently expressed n terms of acidity functions, and a number of these are plotted in Figure 10 for bases n DMSO-water and DMSO-methanol systems.
Alkoxides differ in their solubilities n DMSO. Thus, potassium t-butoxide is more soluble than some lower alkoxides (17). The solubilities of these hydroxylic bases are also shown in Table IX for comparative purposes."

And so on...

This site rules.

Nicodem - 22-1-2010 at 13:30

There are at least two reactions that bear Ullmann's name (some say three):

- The Ullmann biaryl synthesis (also called Ullmann (biaryl) coupling).
See reviews: (a) Synthesis (1974) 9-21. (b) Russian Chemical Reviews, 31 (1972) 1046-1059. (c) Chem. Rev., 38, 1946, 139-196.
Org. Syn. example: http://www.orgsyn.org/orgsyn/prep.asp?prep=cv3p0339 (2,2'-dinitrobiphenyl)

- Ullmann condensation (a Cu-catalysed nucleophilic substitution at aryl halides or triflates; it is sometimes also called the Ullmann-Goldberg reaction; the variation using Pd-catalysis and amines as nucleophiles is now called Buchwald-Hartwig amination). It is sometimes considered to proceed via SRN1 mechanism, but this is not certain.
See reviews: (a) Russian Chemical Reviews, 43 (1974) 679-689. (b) Synlett, (2003) 2428-2439. (c) Coordination Chemistry Reviews, 248 (2004) (d) Tetrahedron, 56 (2000) 5045-5065 (e) Tetrahedron, 40 (1984) 1433-1456.
Org. Syn. example: http://www.orgsyn.org/orgsyn/prep.asp?prep=cv2p0445 (p-nitrodiphenyl ether), http://www.orgsyn.org/orgsyn/prep.asp?prep=cv2p0015 (N-phenylanthranilic acid)

Obviously you are asking about the Ullmann condensation reaction.
There seems to be a great deal of confusion with Ullmann name reactions. People often mix up the two as you can also see from the completely mixed up Wikipedia entries. Furthermore, it is now common to call just about any of the many reductive homo- or cross-couplings of aryl halides as Ullmany (type) coupling even when no Cu is involved.

PS: You need to provide references when opening new threads so that a starting point for a discussion is set. Your "some papers...some...and some" is highly annoying as you did not put a single reference where they should stand. How are we supposed to know why is anything done some way if you don't cite sources? Also, there was plenty of discussion on this reaction at this forum. The least you can do is to read what was already said and link the pertaining threads.

gardenvariety - 22-1-2010 at 13:47

I apologize for the lack of references -- I was simply giving a quick overview of what conditions I had read, rather than any dissection of specific papers or comprehensive listing. I'll cite papers when delving into specifics.

On existing threads, I spent a good chunk of time banging on the search engine here and didn't find much. Better luck next time, I hope.

Nicodem - 24-1-2010 at 12:55

Quote: Originally posted by gardenvariety  
On existing threads, I spent a good chunk of time banging on the search engine here and didn't find much. Better luck next time, I hope.

That you did not find much is hard to believe. Not only that we had plenty of discussions on the topic, but at least one member posted an excellent write up on his successful experience with the Ullmann condensation reaction with an alkoxide as nucleophile. He even gives details of unsuccessful experiments, like with the in situ acac ligand formation method you mention (but fail to cite) in your first post above. Maybe you were unable to find these threads because his screen name is Ullmann and you dismissed his posts as unrelated to the reaction itself? With this hint now you should have less trouble finding what you look for.

gardenvariety - 16-2-2010 at 22:26

Anyone tried this with magnesium methoxide rather than sodium? I believe that the actual reactive species is Cu(I)OCH3, which would be a % of the sodium methoxide solution. Any reason why Mg wouldn't work similarly?

Sandmeyer - 17-2-2010 at 06:58

Quote: Originally posted by gardenvariety  
I apologize for the lack of references -- I was simply giving a quick overview of what conditions I had read, rather than any dissection of specific papers or comprehensive listing. I'll cite papers when delving into specifics.

On existing threads, I spent a good chunk of time banging on the search engine here and didn't find much. Better luck next time, I hope.



There is a book called Strategic Applications of Named Reactions.

A couple years ago I purchased this book because at that time it was not available as a scanned version, later a scanned version appeared but it was black and white and of low quality, now I did a quick search and indeed there is a scanned colour version as well (colour is important for this book).

Some of references (reviews) provided in this thread are obtained from that book.

It is a great resource, for every covered name reaction the authors provide references in the systematic format "Seminal publications", "Reviews" and "Modifications and Improvements".

You can search for it at Giga.

So you can simply go to the reference section and look up the reviews for yourself.

;)

Sandmeyer - 17-2-2010 at 20:39

Of the important reviews, Chem. Rev., 38, 1946, 139-196 (this one is cited up-thread), Chem. Rev. 1951, 49, 273-412. and Chem. Rev. 2002, 102, 1359-1469 (which is a highly recommended read!) were covered by Strategic Applications of Named Reactions. After the book was published, three other important reviews appeared:


Evano, Gwilherm; Blanchard, Nicolas; Toumi, Mathieu. Copper-Mediated Coupling Reactions and Their Applications in Natural Products and Designed Biomolecules Synthesis.
Chem. Rev. (2008), 108(8), 3054-3131.

Monnier, Florian; Taillefer, Marc. Catalytic C-C, C-N, and C-O Ullmann-Type Coupling Reactions.
Angew. Chem., Int. Ed. (2009), 48(38), 6954-6971

Monnier, Florian; Taillefer, Marc. Catalytic C-C, C-N, and C-O Ullmann-type coupling reactions: copper makes a difference.
Angew. Chem. Int. Ed. (2008), 47(17), 3096-3099.

Additionally, a Slovenian group published a review in 2006:

Recent progress in diaryl ether synthesis. Frlan, Rok; Kikelj, Danijel. Synthesis (2006), (14), 2271-2285

JohnWW - 22-2-2010 at 06:15

Strategic Applications Of Named Reactions In Organic Synthesis
- Laszlo Kürti & Barbara Czakó (Academic Press - 2005)

I have uploaded this reference book on synthetic organic chemistry on my Rapidshare premium account, because of its importance, and because the existing uploads of the PDF file are few in number, and these previous uploads do not include the 44-page Index at the back of the book (pages 715-758, which I have supplied) which is essential for use of the book.

Book Description:

The most advanced organic reaction reference work ever written, including 250 extensive color reactions, hundreds of examples and thousands of references, in an organized user-friendly format.

Kurti and Czako have produced an indispensable tool for specialists and non-specialists in organic chemistry. This innovative reference work includes 250 organic reactions and their strategic use in the synthesis of complex natural and unnatural products. Reactions are thoroughly discussed in a convenient, two-page layout--using full color. Its comprehensive coverage, superb organization, quality of presentation, and wealth of references, make this a necessity for every organic chemist.

* The first reference work on named reactions to present colored schemes for easier understanding
* 250 frequently used named reactions are presented in a convenient two-page layout with numerous examples
* An opening list of abbreviations includes both structures and chemical names
* Contains more than 10,000 references grouped by seminal papers, reviews, modifications, and theoretical works
* Appendices list reactions in order of discovery, group by contemporary usage, and provide additional study tools
* Extensive index quickly locates information using words found in text and drawings.

The Rapidshare link for downloading the ebook is given in the Organic Chemistry Books thread in the References section. Those who do not have password access to the References can ask me privately for the Rapidshare link.

JohnWW - 23-2-2010 at 19:44

Strategic Applications Of Named Reactions In Organic Synthesis
- Laszlo Kürti & Barbara Czakó (Academic Press - 2005) - continued

I have since found another PDF version of this book, which differs from the above monochrome scanned version, in having bookmarks, OCRed searchable text, color illustrations, Preface, Foreword, Contents, and Index, but without the covers. It could only be found in the Great Science Textbooks 2007 DVD Torrent, May 2009 Supplement. Although it has advantages, I suspect that it may be at a lower resolution than the above scanned version.

The Rapidshare link for downloading the ebook is given in the Organic Chemistry Books thread in the References section. Those who do not have password access to the References can ask me privately for the Rapidshare link.


[Edited on 24-2-10 by JohnWW]

Sandmeyer - 24-2-2010 at 08:08

I can repeat what I said in my first post (this thread) - the colour version of the book can be obtained via giga*****.

The book was requested here at sciencemadness by rim001 back in 2005.

The book itself was later posted to a Chinese forum http://bbs.ok6ok.com/read.php?tid=135626 in late 2007 and ayush uploaded it to rapidshare https://www.sciencemadness.org/whisper/viewthread.php?tid=43... all this is for the old black-and-white non-OCRed version. As I mentioned it is now available as a colour version at giga.

chemrox - 24-2-2010 at 11:18

I did a search for Ullmann condensation and got about 10 hits. Some of these were related to Ullmann's Encyclopedia and a poster named "Ullmann" . Of the 10 several were about Ullmann condensation reactions with one by "Ullmann" giving lots of details on a synthesis. What is, "Bulletin 105 from Gaylords?" Please cite them here as you would in a paper.

gardenvariety - 25-2-2010 at 14:39

Thanks, Sandmeyer and JohnWW. I found the 'Named Reactions' color scan on another site and yeah, it's the bomb.

chemrox, I didn't do a search for Ullman, because I didn't think this reaction was called an Ullman. I did several searches on alkoxides, copper, DMF, and aryl halide, but while I found a number of interesting threads, I didn't find any good threads covering mechanisms.

The Gaylord Bulletin 105 I found on one of those threads, here is the link: http://www.gaylordchemical.com/bulletins/Bulletin105B/index....

Anyway, now I know.

[Edited on 25-2-2010 by gardenvariety]

Sandmeyer - 26-2-2010 at 07:33

gardenvariety, I'm glad you liked the book and thanks for that DMSO bulletin - it is highly interesting. If you can not access the Ullmann reviews that I cited above I could PM.