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Topic: First Org Chem Exam, and i was completly lost with this problem...  (Read 3745 times)

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Offline rajm95

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I've been trying to solve this problem all day long, and so far i haven't made any progress[its getting me nuts]...
If you could explain me whats going on, I would be very grateful.
« Last Edit: February 22, 2015, 05:53:29 AM by Arkcon »

Offline discodermolide

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Re: First Org Chem Exam, and i was completly lost with this problem...
« Reply #1 on: February 22, 2015, 01:58:40 AM »
In the starting material, what do you know about the two hydrogens between the carbonyl and the nitrile group?
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Offline rajm95

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Re: First Org Chem Exam, and i was completly lost with this problem...
« Reply #2 on: February 22, 2015, 02:17:42 AM »
In the starting material, what do you know about the two hydrogens between the carbonyl and the nitrile group?

you do have two hidrogens hanging in there, Cycle-CO2-CH2-CH2N
By "what do I know", what type of information are you looking for?


Offline discodermolide

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Re: First Org Chem Exam, and i was completly lost with this problem...
« Reply #3 on: February 22, 2015, 03:02:43 AM »
Well the are between 2 electron withdrawing groups, does this tell you anything?
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Offline rajm95

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Re: First Org Chem Exam, and i was completly lost with this problem...
« Reply #4 on: February 22, 2015, 03:54:58 AM »
Well the are between 2 electron withdrawing groups, does this tell you anything?
it doesnt, i have my organic chemistry book[klein] by myside and my computer,  [what should i look on them to understand this better]?

What i figured out is that the Br will leave, and when it does, the carbon on the buttom will be left with a (+) charge making it easy for the oxigen to make a bond[by changing it self to O (-) using the electrons on the double bond next to it].

the things i dont understand, are:
firstly what is the function of NaH and THF on the reaction.
secondly is that ive been tought Carbons cant have more that four bonds, but on the product side of the mechanims you have the carbon with a double bond, a bond with the nitrile and i  the two hydrogens leaving you with a total of 5 bonds...
So how do i get rid of the extra H, and how do i form a double bond between the carbons??
How do i make ithe bond between the O (-) and the C (+) be formed on the "back" of the molecule??

Ps:im sorry for my english, and my lack of knowledge.

Offline discodermolide

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Re: First Org Chem Exam, and i was completly lost with this problem...
« Reply #5 on: February 22, 2015, 04:08:54 AM »
The two hydrogens I am talking about are acidic because of the electron withdrawing groups carbonyl and nitrile. The NaH removes one of them to give an anion which is resonance stabilised.
Can you draw the resonance structures?
If it was in the exam you must have covered this in class, go back and look at your notes.
« Last Edit: February 22, 2015, 04:51:44 AM by discodermolide »
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Offline Dan

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Re: First Org Chem Exam, and i was completly lost with this problem...
« Reply #6 on: February 22, 2015, 04:48:46 AM »
firstly what is the function of NaH and THF on the reaction.

A clue:
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Offline darkdevil

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Re: First Org Chem Exam, and i was completly lost with this problem...
« Reply #7 on: February 25, 2015, 04:55:12 AM »
Hydride is a very strong BASE.
Whenever you see a strong base in the condition, you then look for its counterpart which is the acid!
And now you shall look at the starting material, what is acidic in the compound? look for any acid proton first, if there are no acidic protons, go on to look for any electrophiles and you will see how the reaction goes!

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