[Doc Oc]

Anybody have experience with these?  Both me and a colleague have tried these and we can't get complete conversion, 80% is the best either of us has gotten.  Under the standard reaction conditions (NaI, acetone) I can only get 50%, and this is a primary alkyl chloride.

Any tips or pointers from people with better know-how?

[opsomath]

I only tried this guy once, it was to make the iodide from an allylic tosylate. I like the use of the tosylate much better if you can start from the alcohol, then you don't have to worry about starting material hanging around. Anyway my product was volatile so I had losses on the rotovap, but the reaction itself worked fine.

[g-bones]

Have you looked into using TBAI instead?  Might make a slight difference.  Are you running these reactions at reflux? The  alkyl iodide you are making, is it eventually for a displacement reaction? if so, how about throwing in your nucleophile with the NaI or TBAI (can even be catalytic if you want) to trap your electrophile as soon as its generated and removing it from that portion of the equilibrium?

[the.khemist.ds]

Never attempted the reaction myself. Just had a quick search of ChemSpider Synthetic Pages - I found one procedure which might be of interest to you.
http://dx.doi.org/10.1039/SP95
Hope it's helpful

[opsomath]

I just wanted to second g-bones' suggestion. If you're just trying to speed up an SN2 reaction, that can be efficiently done by adding 5-10% iodide to the other alkyl halide in DMF or similar, and adding your nucleophile (phenolate, thiolate, what have you) to that mix. You can run this catalytically, in other words, without the need to prep and isolate.

[Doc Oc]

Thanks for the input everyone.

1) My SM is the alkyl chloride.  I suppose I could always try to convert that to the alcohol, but it's a bit roundabout.
2) My colleague did try tetrabutylammonium iodide and it was a mess.  Also tried KI w/18-Crown-6, and that got to 80% conversion.
3) Saw some lit yesterday showing that heating the reaction to just below reflux (40-45 deg) works, and it improved both of our conversions to ~70%.
4) I may try that trapping with the nucleophile thing, since obviously the precipitation of the NaCl isn't enough to drive the reaction to completion.

Suggestions still welcome, but I'm going to try some of this stuff and let you know how it works out.

[gvic]

Are you drying your acetone before using it? I've never done the reaction but a quick read on wikipedia indicates that the differential solubility of NaI versus other sodium halides is what drives the reaction forward. Acetone is very hygroscopic and the presence of water might encourage other sodium halides to stay in solution. Throw some CaSO₄ into the mix and reflux

[orgopete]

I agree with the ideas posted. This is an equilibrium reaction. If it is stopping at 70-80%, I would isolate, and repeat. This will increase I/Cl ratio and should increase yield. I am presuming the results are not due to incomplete reaction, that is, increasing the time would increase the conversion. I am presuming the reaction is stopping at 80% due to the build up of chloride and depletion of iodide. A phase transfer reagent may affect the solubility or availability of chloride to react.

[fledarmus]

The other thing you might try is running this essentially in situ, if your iodide won't do anything else in your next reaction. I have gotten alkyl chlorides to react just by throwing a catalytic amount of sodium iodide in the reaction mix.

[Doc Oc]

Just some follow-up on this.

I heated the reaction to 40 overnight and got the conversion to ~95%.  I did use anhydrous acetone for this reaction, and we also bought calcium sulfate so I can distill it if I need more.  I will probably take the 95:5 mix through to the next step because there's a limited number of side reactions that can occur.

Thanks again for all your suggestions.

[Polly Murs]

will using KI instead of NaI achieve the same result in terms of solubility differences, i.e. which would be more soluble in acetone... KBr or NaBr?

thanks