Originally posted by chemrox
Oustanding!
I have a few questions and I should photo the setup I was using for you but first let me ask:
1) the hemple column- I could sub in any fractionating column right? what is it helping you separate out? ethanol .. acetate? .. both?
The column helps to seperate any unreacted alcohol which then refluxes back down into the flask. I'd say 300mm is minimum
with faster results being gotten from a 400-500mm column due to increased reflux ratio.
2) In the procedure I was following (until the fucking phone calls etc.) mandated running the ethanol below the surface of the organosulfate H2SO4
mixture. I take it you dispensed with that as unecessary? and you didn't use a stirrer in place of it either?
Yup, works just fine to just drop it on top... you can actually see the drops floating around on the surface dancing around
and shrinking. I think Vogel was wanting a catalytic reaction in which the alcohol is quickly converted and distilled over along with the water. And
yeah, a magnetic stirrer makes things go much more smoothly... in fact I believe it is necessary to equlibriate the acid/heat/mixture.
I have a condenser like that but it has 29/32 joints and I was using the converters to buy some distance to attach the tubbing to the addition funnel
tip. Long story .. goes with the Vogel's instructions I was trying to be scrupulous about. I really like keeping the ice in a cooler like that.
Looks like you were in the garage with the furnace (?)
Nah its an old shed out back used for storage. It was built a long time ago by my grandfather who used to smoke hams in the
back. The picture best I can remember was takin while it was still fairly hot outside... daytime temps around 90ºF best I can recall I was going thru
about 40lbs of ice in a period of 6 hours just to make a liter... most of it was melting due to ambient heat absorbed from the condensor lines and on
the outside of the condensor... I imagine with some foam insulation on the cooling lines efficiancy could be increased 30% or so.... it might not hurt
to switch over to neoprene either.
I see tubing from the vacuum adapter. Out the window? neighbors? or down the sink with the water .. what i did.
Out the freaking window. Had a rather large fan behind me blowing air in from the opposite direction. With the ice in the
condensor and ice and the cooler you could sniff the vent line and not even get a buzz. Nearest neighbor is about a quarter mile away so no smell
issues.
I just re-read and edited.
You didn't go subsurface with the alcohol but feel you might improve yield by doing so. I'm going to send my condenser up to the glassblower and have
the tapers changed to 24/40 to match everything else I use.
You can buy one off of ebay just like the one in the pic for $70 or so from kantu200 IIRC... personally that is about the
only thing I would buy from them because IMO it isn't exactly the highest quality glass out there, but you can't beat the price on a condensor like
that as a similar one would cost over $200 from just about any of the major glass manufacturers in the USA... the condensor in the pic is 400mm long
and with ether it just about needs every bit of it. If you want a sub surface adapter, you can get one from expediglass cheap.[/red]
I have a number of 29/32 female 90 degree adapters with long tubes if you or anyone you know can use 'em. They came with my addition funnels from an
ebay buy. anyway, I've got some fractionating column choices. I wasn't clear on that. In the usual way you might insulate the columns or even heat
them to the same temp as the takeoff liquid. Is that something you might do to improve separation?
You want to COOL the column to increase seperation.. Ether has such an insane partial vapor pressure it'll come right over
when the top of the column is just warm.
Did you then wsh the product with NaOH?
Actually you can put some NaOH solution in the reciever flask... that will save you a washing step later on... then hit it
with an equal volume of fairly concentrated pre-made and ice cold CaCl/H20 solution... that will rid it of the alcohol and quite a bit of the water
since CaCl forms an addition product with alcohol... finally, sprinkle in some oven dried CaCl, let sit for a few hours under ice and distill directly
from that. Peroxides should be undetectable at this point so you can go close to dryness.
I realized after I'd placed it that the drying tube was pintless as I would have to wash the ether to get rid of acids and any oxides.
Did you get any ester formation or was that the result of my overheating?
Nope, nada... well I take that back.. you do get some EtHSO4 in the spent acid, but other than that there should be no
esters formed since there is no acids going in other than the sulfuric. Even if you did somehow create ethyl acetate or whatever, the esters would not
be able to come over with the fractionating column in place. My guess is you used sulfuric acid drain cleaner which has god knows what all in it...
use only ACS grade sulfuric for best results.
What do you predict getting from too much heat?
Well supposedly ethylene gas.
Was glassware cleanup an issue?
Yes, very much so. Back then I was using joint grease. That shit is a total pain in the ass to remove and contaminates
everythign. I switched over to teflon joint sleeves, and they work much much better... other than that, just rinse with water and mild detergent like
simple green... hell the acid starts out clear and when its done is slightly tan.
[Edited on 28-9-2007 by chemrox] |