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Topic: Wittig reaction  (Read 6056 times)

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Offline vivekfan

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Wittig reaction
« on: June 07, 2009, 10:13:43 AM »
Is the mechanism important to know for the overall reaction for organic chemistry I or can I stick to the overall reaction...what would someone recommend?

Offline Fridushka

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Re: Wittig reaction
« Reply #1 on: June 07, 2009, 10:36:42 AM »
well it depends on your teacher!..if they ask you then its important if they dont its not..! so i cant say anything..well in my case now im taking organic 1 and my instructor never asked any mechanism on the 1st exam although she lectured every single one..well you have to study all the overall reactions and also the catalyst needed in each and heat and so on..because such things was asked..but better to understand the mechanism for each reaction. Furthermore, dont forget that it depends on your instructor!

Good Luck!!

Offline english

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Re: Wittig reaction
« Reply #2 on: June 07, 2009, 01:48:30 PM »
I'd recommend you try and understand the basic mechanism and then recognize the overall transformation.  Understanding the overall transformation can be more valuable when situations arise that require you to give a synthetic scheme.  In these situations, it will save you a lot of time.

There are shortcuts to helping yourself remember how certain mechanisms occur, as well as tools you can learn later on to help you come up with mechanisms for reactions you've never even seen before.  In the Wittig reaction, for example, the side product is a phosphine oxide (a pain in the ass, from personal experience ;)).  Really if you remember this detail, it can save you a lot of trouble.

In the end everyone has their own means.  Find what works best for you and remember to not get bogged down in mechanistic details, unless of course you're into that sort of thing.

Offline orgopete

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Re: Wittig reaction
« Reply #3 on: June 07, 2009, 06:38:29 PM »
This is an analogy that I sometimes use. If you are learning to do multiplication and the first examples are 10, 100, or 1000 times some number, do you need to learn to do multicolumn multiplication or can you just add the zeros? Organic chemistry can be like that. Why learn to multiply when all you need to do is add the zeros? Why learn the mechanism if you know the products?

So if they give you a multiplication problem and they ask you to multiply by 1100, can you do it? Will knowing how a reaction takes place get in the way? For me, a mechanism is the chemistry. It is simply an explanation of why a reaction leads to a given product.

In my classes, I focussed on reaction mechanisms. By doing so, I was able to raise my class average by over 20 percentile points on the ACS organic chemistry exam.

I don't know anyone who is a serious organic chemist that doesn't know reaction mechanisms. In my industrial career, I relied completely on the reaction mechanisms that I first learned as an undergraduate. Reaction mechanisms are fundamental to organic synthesis.

While I do believe that learning reaction mechanisms is the best way to learn organic chemistry, I also understand the opinion of others who would disagree. Many (most?) professors pay lip service to mechanisms. Many of them do not believe that students can even learn them, therefore they avoid reliance on tests that require mechanistic knowledge (are old tests posted and they are similar?). In that case, it would be asking a student to go beyond what a professor is asking. However, if you are beginning to become confused by the variety of reagents and products that may form, it is because memorization is not a substitute for knowledge. Students that know the mechanisms generally do not suffer this same confusion.
Author of a multi-tiered example based workbook for learning organic chemistry mechanisms.

Offline orgopete

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Re: Wittig reaction
« Reply #4 on: June 07, 2009, 07:16:44 PM »
See this problem. If the questioner knew the aldol mechanism, I doubt the question would be asked.
Author of a multi-tiered example based workbook for learning organic chemistry mechanisms.

Offline vivekfan

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Re: Wittig reaction
« Reply #5 on: June 07, 2009, 11:22:08 PM »
See this problem. If the questioner knew the aldol mechanism, I doubt the question would be asked.

Thanks for the advice. :) I will definitely keep it in mind as I continue to study organic.

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