Daphuk_up (Hive Bee)
03-26-04 03:41
No 497408
       Nitroethane-hexane mixture.     

Would it be reasonable to assume that if one had a mixture of roughly 40mL nitroethane and 250mL heptane (which refused to seperate via fractional distillation, forming a smooth curve of azeotropes), that it could be extracted with 12M aq. NaOH, which could then be seperated and titrated with HCl to neutrality, at which point the nitroethane would precipitate from the water solution?  Or would it be necessary to extract from the neutralized water solution with a different, easier to fractionally distill non-polar solvent (say, diethyl ether)?
Drug Chemists are Ta to a good Sm. 		 
 
 
 
    Rhodium
(Chief Bee)
03-26-04 08:41
No 497462
       si, da, ja, yes     

Or would it be necessary to extract from the neutralized water solution with a different, easier to fractionally distill non-polar solvent (say, diethyl ether)?

Yes, that is encouraged.
The Hive - Clandestine Chemists Without Borders 		 
 
 
 
    Daphuk_up
(Hive Bee)
03-26-04 21:24
No 497560
       Thanks for the confirmation.     

Thanks for the confirmation. smile SWID apologizes for asking simple noobish questions, but it is the simple things that are most undocumented.  And given SWIDs string of failures, he is hesitant to proceed in most cases.

EDIT:  SWID thinks the above statement is inaccurate enough to be considered false.  Rather, it would be more accurate to say that certain elements of specific descriptive chemistry aren't heavily documented due to it being considered 'common knowledge' by those proficient in the field, and as such finding what little documentation there is proves to be difficult.  Although a solid working knowledge of the mechanistics and trends can help provide a solid predicition of how a reaction will proceed, there are always exceptions.  For instance, it would not have suprised SWID if the nitroethane would refuse to fall out of an aqueous solution even after titration to pH7, thereby absolutely requiring extraction with a second, inmiscible solvent.  SWID just wanted to illucidate the point he intended to make.
Drug Chemists are Ta to a good Sm. 		 
 
 
 
    Daphuk_up
(Hive Bee)
03-29-04 10:45
No 497950
       Two quickies     

1.  Will leaving the above titrated solution, which was over titrated to pH0, 24h in the cooler cause harm to the nitroethane?  (SWID has a bad sinking feeling about this frown)

2.  Is there any reason to think that DCM would NOT be a suitable substitute for diethyl ether in the extraction?

SWID titrated his 12M extract (50mL x6, 50mL dH20 x2) with HCl, and towards the end there appeared to be a seperate layer on the bottom.  Unfortunately it was very late, and SWID had to cap the flask and throw it in the cooler, where it sat for ~24h before exctraction with 8x 25mL DCM occured (SWID noticed layer was gone at this point).  Upon distilling off the DCM, SWID was left with maybe .5mL of a thick orange-brown goo.  SWID has kept all mother liquors and washes, so if the nitroethane lies elsewhere it can still be recovered.
Drug Chemists are Ta to a good Sm.