[nil]

Hi folks!
I have a problem with the following problem.
Take any methyl halide and prepare methyl iodide.Choose the appropriate solvent.

Now what i know is here we are going by SN2 mech and replacing a halide by iodide ion.But the problem i am facing is how can i replace a other halide by a iodide ion because my book says iodide is the best leaving group among all halides.So i am confused how will this happen.

[Dan]

Have you looked up the order of nucleophilicity of the halogens?

[nil]

Have you looked up the order of nucleophilicity of the halogens?

in aprotic solvents the nucleophilicity order is like:

F^->Cl^->Br^->I^-

[Dan]

Have you looked up the order of nucleophilicity of the halogens?

in aprotic solvents the nucleophilicity order is like:

F^->Cl^->Br^->I^-

You are saying F^- is the most nucleophilic? What is your source for this data?

[nil]

Have you looked up the order of nucleophilicity of the halogens?

in aprotic solvents the nucleophilicity order is like:

F^->Cl^->Br^->I^-

You are saying F^- is the most nucleophilic? What is your source for this data?

this is from the exact same book here-http://www.amazon.in/Solomons-Fryhles-Organic-Chemistry-Advanced/dp/8126541814?tag=googinhydr18418-21&kpid=8126541814&tag=googinkenshoo-21&ascsubtag=463a991a-1183-b168-0ada-0000722e4419

it is an adopted version of solomons and fryle or.chem

[Dan]

Have you looked up the order of nucleophilicity of the halogens?

in aprotic solvents the nucleophilicity order is like:

F^->Cl^->Br^->I^-

You are saying F^- is the most nucleophilic? What is your source for this data?

this is from the exact same book here-http://www.amazon.in/Solomons-Fryhles-Organic-Chemistry-Advanced/dp/8126541814?tag=googinhydr18418-21&kpid=8126541814&tag=googinkenshoo-21&ascsubtag=463a991a-1183-b168-0ada-0000722e4419

it is an adopted version of solomons and fryle or.chem

I don't believe it says that F^- is the most nucleophilic halogen. Post a photograph of the sentence/paragraph where it says this.

[orgopete]

I understand the quandary, but I think the actual answer does not involve nucleophilicity. I think even a poor nucleophile would succeed.

Indeed, iodide is a paradox. It is a good nucleophile and good leaving group. It would seem that chloride could also displace iodide. However, in this case it should be pointed out that sodium iodide is soluble in acetone while sodium chloride is not. Given these conditions, what effect on the reaction would a high iodide and low chloride concentration have on an SN2 reaction?

[nil]

Have you looked up the order of nucleophilicity of the halogens?

in aprotic solvents the nucleophilicity order is like:

F^->Cl^->Br^->I^-

You are saying F^- is the most nucleophilic? What is your source for this data?

this is from the exact same book here-http://www.amazon.in/Solomons-Fryhles-Organic-Chemistry-Advanced/dp/8126541814?tag=googinhydr18418-21&kpid=8126541814&tag=googinkenshoo-21&ascsubtag=463a991a-1183-b168-0ada-0000722e4419

it is an adopted version of solomons and fryle or.chem

I don't believe it says that F^- is the most nucleophilic halogen. Post a photograph of the sentence/paragraph where it says this.

yes F^- is strongest nucleophile in aprotic solvets.You can even get this if you can google it!

[nil]

I understand the quandary, but I think the actual answer does not involve nucleophilicity. I think even a poor nucleophile would succeed.

Indeed, iodide is a paradox. It is a good nucleophile and good leaving group. It would seem that chloride could also displace iodide. However, in this case it should be pointed out that sodium iodide is soluble in acetone while sodium chloride is not. Given these conditions, what effect on the reaction would a high iodide and low chloride concentration have on an SN2 reaction?

so for your  last question,according to Le chateliar's principles the reaction should move forward.Isn't it?And can we call I^- an exception?Can it displace Cl^- without the need of sodium ion??

[Babcock_Hall]

nil,

The thermodynamics of the reaction are strongly influenced by the insolubility of NaCl in the example given by Orgopete.  Yes, I think one could invoke LeChatelier's principle.

[Dan]

My mistake, sorry everyone.

[jstownse]

Look up procedure for Finkelstein Rxn. It involves the exchange of a chloro or bromo with an iodo, as you have described. It is performed by refluxing your halogenated species in acetone while in the presence of Sodium Iodide (NaI). Bingo Bango.