which is the best solvent for LiAlH4 rxn?

[Toothguy80]

ethanol
1,2-ethanediol
propanoic acid
N,N-dimethylpropanamide
triethyl amine

Isn't it ethanol, Kaplan seems to think otherwise...I always see rxns with LiAlH4 with EtOH as their solvent...help!!!!!

Im taking the test in a few days so Im nervous, so expect a lot of questions from me...

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[dantheman2007]

when are you taking the test, and where?
Best of Luck,
Dan

 

[Vapor1122]

According to my notes from when I took organic II, it's ether. EtOH is for NaBH4.

 

[digitalasylum7]

Its definitely ETOH

 

[digitalasylum7]

Excuse the typo: I meant ET20

 

[Toothguy80]

Kaplan says that it's

triethylamine

why?

the choices were....
ethanol
1,2-ethanediol
propanoic acid
N,N-dimethylpropanamide
triethylamine

 

[joefosho315]

From what I remember, it is triethylamine because it lacks and acidic protons. LiAlH4 is best used in solvents that do not contain acidic protons, such as H2O (this will cause your solution to explode!). Similar to Grignard Reagents, and their tendencies to react viciously with acidic protons, the best solvents are usually ether or triethylamine.

Edit: oops, I meant triethylamine, not trimethylamine. Though you would have the same result.

 

[sacjumpman]

From what I remember, it is trimethylamine because it lacks and acidic protons. LiAlH4 is best used in solvents that do not contain acidic protons, such as H2O (this will cause your solution to explode!). Similar to Grignard Reagents, and their tendencies to react viciously with acidic protons, the best solvents are usually ether or triethylamine.

Bingo. Well said.

 

[levyusupov]

form what i understand kaplan confuse all the people in the orgo and the gchem section. if you just stick out with the destroyer on these two sections you will be more then ready for the DAT and less confused.

and BTW, in the desteoyer the answer is ethanol.

 

[joefosho315]

form what i understand kaplan confuse all the people in the orgo and the gchem section. if you just stick out with the destroyer on these two sections you will be more then ready for the DAT and less confused.

and BTW, in the desteoyer the answer is ethanol.

Hmm, could you point to which question says that Ethanol works as a solvent for LiAlH4? I know that there are errors sometimes in the destroyer, so I would like to know! However, at least destroyer problem #73 states that the solvent should be Et2O (ether, CH3CH2-O-CH2CH3). Is it possible that you may have misread it to say EtOH?

 

[Joey413]

It was probably Et20 and triethylamine is right. Anything without acidic protons is cool otherwise you get an explosion due to lithuim aluminum hydride's highly exothermic rxn with acidic protons. Anyway, I agree with lev, kaplan is a bit confusing..try the destroyer problems I think they are clear cut..