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Author: Subject: Synthesis from Patents?
Ahab
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[*] posted on 15-11-2009 at 19:17
Synthesis from Patents?


Hi everyone,

Here's a n00b question... I was looking over patents the other day when i should've been in the lab doing real work. I came upon a few patents detailing the use of Rh(I) and Ru(II) catalysts for one step conversion of an alkenol to the saturated ketone via Hydrogen shift to the enol, by simply refluxing the alkenol in propanol in the presence of the catalyst under argon. In our lab we've been using a standard Pd/C hydrogenation followed by Oppenauer oxidation to achieve the same results. I don't have the patent refs handy, i'll try and find them again when i'm on campus tomorrow, but this seems like a much more efficient approach.

I don't have much experience with following protocols from patents and i was wondering how they 'detailed' they are with respect to the actual requirements for success. i.e. is it safe to assume that if anhydrous alcohol is not explicitly stated, that absolute dryness isn't required? is there any way to contact patent holders to get more information about their protocol?

Specifically, i'm wondering about the required dryness and purity of propanol, and what effect water would have on the reaction, if any... mostly because I'm lazy and hate prepping anh. degassed solvents ;)
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Arrhenius
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[*] posted on 15-11-2009 at 20:36


This is a well known phenomenon of "alkene transposition" of allyl alcohols when you perform a hydrogenation under low pressure (or no H2). Brown's catalyst and Wilkinson's catalyst (both Rhodium) are known to do this, as are palladium or platinum. It's not often use preparatively though. It shouldn't need to be dry. Just use ethanol, isopropanol or ethyl acetate.

[Edited on 16-11-2009 by Arrhenius]
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merrlin
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[*] posted on 16-11-2009 at 13:50


The patent law (35 U.S.C. 112) requires that:

"The specification shall contain a written description of the invention, and of the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to make and use the same, and shall set forth the best mode contemplated by the inventor of carrying out his invention."

Even though the statute does not use the term "undue experimentation," it has been interpreted (by the courts) to require that the claimed invention be enabled so that any person skilled in the art can make and use the invention without undue experimentation. It has also been held that a patent need not teach, and preferably omits, what is well known in the art.

An inventor's city of residence is usually listed on the patent, as is the assignee; if there is one. If the patent isn't too old, you can try contacting the assignee or search a local phone directory.

The usefulness of a patent's specification can depend upon how one defines "skilled in the art" and "undue experimentation." The references cited in a patent may also be instructive.
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Vogelzang
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[*] posted on 16-11-2009 at 14:57


Look at all of the references listed in each patent, including other patents, articles and books. Look up the classification of each patent and look up the classes and subclasses in the manual of classification and then search the appropriate subclasses. The agents and/or attornies and/or inventors wrote/write patents and the employees at the USPTO aren't allowed to write patents. The examiner can object to the specification and/or suggest amendments to claims which he/she can make with the permission of the applicant.

They threw away all of the paper patents at the USPTO and now have them all on computer databases. You can see how fast the EAST database is in this video. The camera that recorded this video is low resolution. The resolution on the EAST system is actually higher than 1024 X 768. I don't know the exact resolution. The patent images are multi-page TIFF. Searching patents on the EAST system at the USPTO is at least a thousand times faster than using the internet for searching patents (unless there's a secret internet II system working somewhere). They even have free WiFi in the public search room and lobby.

http://www.4shared.com/account/file/112841042/b3a64204/EAST1...

They took this out for some reason:
http://www.4shared.com/account/file/39266902/4cd19191/Andrew...

There's various depository libraries around the country which have patent databases. I heard most have WEST and some have EAST. Some companies also have their own databases.





[Edited on 16-11-2009 by Vogelzang]

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not_important
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[*] posted on 16-11-2009 at 18:01


Note that several countries, India being one, allow for "trade secrets" in their patents, meaning important detail can be left out. Even with U.S. patents the phrase "any person skilled in the art to which it pertains" has become a major loophole used to omit critical information.
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[*] posted on 24-11-2009 at 16:59


In my experience you have a fat chance in hell of getting a recent patent to work without significant experimentation. They are written to protect the inventor should someone want to claim the invention but they rarely protect the inventor's actual rights of exclusive ownership.
This is because we live in a greedy capitalist world and everyone has figured out that for chemical processes it's neigh on impossible to litigate a breach of ownership allegation, as such one is instructed by patent attorneys to write up your invention so that it would likely take you as much effort getting it to work than if you had not ever read the patent.
Old patents are OK for chemical processes because they were written for the spirit of the thing.
i am cynical though this is because of my experience, if anyone every quotes patents to me as support for if something should work, i file them with national enquirer articles.
Unfortunately this 'lying without lying' technique is infecting into the peer reviewed publications also.




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Vogelzang
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[*] posted on 25-11-2009 at 11:46


Did you look at any Soviet or Chinese patents?
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[*] posted on 28-11-2009 at 18:13


I have managed to reproduce patent described chemistry.
It depends on the patent and sometimes you have to read between the lines but it is not always down to a wish to hide the details but more down to brevity in the experimental description.
Modern journal articles pack in more chemistry with more examples than say an article from the 1950's and this results in a loss of detail in my opinion.
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