amine in the removal of impurities (1 Viewer)

[oranGez]

not quite sure where to post this, so ill just post here and hope for the best .. in the Spotlight textbook pg. 197, it says an amine solution is used to remove impurities such as CO2 from the ethane fraction (previously obtained from distillation). It says the acidic CO2 reacts with th weakly basic amine groups as follows:

R-NH2 + CO2 + H2O --> R-NH3 + HCO3 (i left out the charge sign thingos)

what i dont get is
a) wheres the ethane
b) how is that removing the CO2.. is it just that its converting it to an acid so it can be removed easier?
c) does the water come from the fact that its an amine solution ?



+-- many thanks

 

[Casmira]

my guess is your on chemical monitoring and management, but I can tell you ethane isn't needed in the reaction, because CO2 impurities vary, and you cant say like C2H6CO2 (as one)- because it wouldnt make sense, so its left out and the only bit that is shown how you get rid of CO2 by changing it

i dont know what converting it to an acid does, my guess is the different bp/mp means you can just fraction the acid out alot easier

the water is used to combine with CO2 present in the impurities to make carbonic acid

 

[oranGez]

thank you v. v. much

i feel so dense

 

[xiao1985]

converting it to bi carbonate ion and amide ion effectively gives it a charge... u can condense the water out (or use fractional funnel) to separate ethane from water)... the charged species are most likely to be inwater (as it interacts strongly in water rather than non polar ethane)