[Dolphinsiu]

Ph ---? (-) Na (+)

+
       CH(CH3)2
       l
Ph-- C --Cl
       l
       CH2CH3

----> Ph -- C = C -- Me
               l      l
              Et    Me

(i) Suggest a feasible mechanism for the formation of the product.
(ii) Write structures of three other feasible products.Indicate in decrease order the yield of all four products with key intermediates or transition state(s), of the reaction.

I have thought one hour, but still have no idea. I am afraid that I will get zero marks in organic chemistry as my test is on 9/5.

[PRIYA1022]

Phenyl acetylide is a base. ..and think about an E2 elimination. Your alkyl halide is tertiary ..
Does this help?

[PRIYA1022]

sorry.. E1..followed by a  methyl shift..

[PRIYA1022]

 NO..Hold on a sec....Are you sure you have the right product... It has to go through an E 2 pathway..Phenyl acetylide is  a very strong base..

[PRIYA1022]

Wait.. I read the question..You are to apply all possible eliminations and give all the possible products. To get the one you have , apply E1 mechanism followed by a methyl shift , and further by a phenyl shift.. That s the only way to reach your product. E2 would be the major product, but not the one you have listed. What do you say?

[Dolphinsiu]

Ph -- C    =    C --  Me
        l            l
       Et         Me

Sorry, my product is this one, but I guess it is via  E2 if strong base is used.
       
  (Leaving
    group)
        Cl     Me
        l       l
Ph -- C  -   C  - Me  ------>  my E2 product (is it correct?)
        l       l
       Et     H ( - C ? Ph)
----------------------------------------------------------------------------------------------
The other two products

Ph -- C -- CH(Me)2
        ll
 H --  C -- CH3

(Trans)          + (Cis)

The third product is what? Thank you!

[alphahydroxy]

My guess for the third product would relate to the reactivity of the acetylide - it could also act as a nucleophile...

And *please* use chemdraw or isis draw to draw your structures! They both have the ability to export structures to jpeg, and that makes it much easier to understand questions rather than using crappy ascii representations of structures!

[Borek]

They both have the ability to export structures to jpeg

jpg is good for photographs/paintings. Structures and plots are usually much better exported as gif or png.

[Dolphinsiu]

Thank you! I know what you are talking. We can treat it as CN triple bond. Nucleophilic substitution ... leaving group is Cl. I know la. Thank you very much!

[alphahydroxy]

They both have the ability to export structures to jpeg

jpg is good for photographs/paintings. Structures and plots are usually much better exported as gif or png.

This may be true, I relly wouldn't know. However, I don't think Isis/draw has the function to export to gif or png - though chemdraw certainly does. In fact, if everybody used chemdraw, the world would be a much brighter place ! 


FAO: Dolphinsiu

You definately cannot treat it as a CN triple bond... I hope this was a typo !!