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When you react a tertiary alkyl halide with acetone,(and nothing else) will there be elimination or substitution?
Acetone is not a nucleophile, so substitution will not take place.
Acetone is not a strong enough base to abstract a hydrogen bonded to a carbon.
So then will elimination take place?
I was under the impression that an SN2 reaction will take place.
For the OP, is there also Sodium Iodide in the solution?
Because I know that there is a reaction in lab tests for alkyl halide unknowns, they use Sodium Iodide/Acetone and combine it with the alkyl halide. The tertiary halide should take the longest to react, 1 > 2 > 3.
I was under the impression that an SN2 reaction will take place.
For the OP, is there also Sodium Iodide in the solution?
Because I know that there is a reaction in lab tests for alkyl halide unknowns, they use Sodium Iodide/Acetone and combine it with the alkyl halide. The tertiary halide should take the longest to react, 1 > 2 > 3.
Acetone is just a solvent for the reaction to take place. It favors Sn2 reaction because it is a polar aprotic solvent.
no reaction
Tertiary alkyl halides DO NOT do SN2 reactions. Too sterically hindered. Also, acetone is NOT a nucleophile. It is an electrophile, therefore, it would NOT react with a tertiary alkyl halide to do an elimination reaction. For E1/E2 or SN1/SN2, you need a nucleophile to attack. When you learn about carbonyl chemistry in ochem, you will see why acetone is an electrophile. In this case, acetone is just the solvent so there would be NO REACTION.
agree. It's a No Reaction problem.
acetone is polar aprotic, which works well with alkyl halides undergoing SN2 reactions (usually primary and secondary).
and tertiary alkyl halides relies on just solvent (for SN1 & E1), which happens to be exclusively polar protic - a weak base ie water, ROH, carboxylic acid. However for E2 to occur with tertiary alkyl halides, you just need a strong base (bulky or non-bulky - it makes a difference which one you use too).
Edit: Polar Protic sovlates nucleophiles. Polar Aprotic solvates cations (never nucleophile). And...if you look at the reaction rate equations of both SN2 and SN1, you'll see that SN2 relies on nucleophile concentration and SN1 does not. That's why solvents are put in place...to do these sort of things...and when you use them in the wrong place like tertiary alkyl halide & acetone, you get NO REACTION!
Also, OchemTA - I learned that tertiary NEVER undergoes any SN2. My professor mentioned it on countless number of occassions. So, in my guesstimate, it's not even worth mentioning that "some" SN2 will occur with tert alkyl halide...im sure it happens in an experiment, but theoretically none should take place because a tert halide is too hindered.
If you don't get it now, you'll get used to this stuff in Organic 2...It's pretty important. Just try understanding it while you can though.
Actually, acetone CAN be a nucleophile. The LP of the oxygen is nucleophillic and will react with the electrophillic hydrogen in acids. This is how carbonyls in hemi-ketal and ketal reactions are activated.
That is considered an acid-base reaction...when you are doing an abstraction of an acidic hydrogen to protonate the O on the carbonyl group. But even doing so, that makes the protonated carbonyl even more electrophilic. And tertiary alkyl halides do not have any acidic hydrogens anyway. We don't need to be that technical to confuse this guy... Just trying to answer the question.
"The chloride anion, as well as the acetone, are poor nucleophiles and very weak bases." Quoted from : http://www.chemgapedia.de/vsengine/...n1_e1_nucleophil/sn1_e1_nucleophil.vscml.html