Here's a relevant (old) post by dpHarma:
dpHarma [Image] posted 03-03-99 02:49 PM
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The following is a dream transcribed during a seance
facilitated by Elton John's road manager.
A meagre 4.5 gms. performic ketone purified w/ bisulfite,
was combined w/ 6 gms. MeNH2.hcl in 30ml. MeOH. (the
MeNH2.hcl was NOT purified of all the ammonium chloride)
this was stirred by hand until uniform suspension then
added to prepared amalgam consisting of 6gms. 'pie
plates' cut into 1cm. squares, 250 mg. HgCl2,
magnetically stirred and heated for 15 min. in 150ml
MeOH.
The ketome/amine was followed by 3.5 gm. NaOH in 5ml. H2O
and 10 ml. MeOH.
An reflux condensor was attached to the flask, and
magnetic stirring and low heat applied for about 18 hrs.
at which time no Al remnants were visible.
The soution was quenched with an equal volume of H2O, and
poured through a plastic kitchen strainer, into a 500ml.
sep funnel.
(a small 'gob' of thick putty like Al amalgam was
recovered in the strainer, and washed and stored under
peth til next time.)
The grey liquid was extracted 4 times w/ toluene, the
aqueous layer set aside, & the toluene extracts washed w/
H2O, and several sat. NaCl/H2O washes. The washes were
set aside, and the cleaned tolune was extracted w/ 3 x
20ml. conc. Hcl in 30 ml H2O.
The 'spent' tolune was set aside, and the acid sol'n
washed w/ 3 x 25 ml. DCM.
the DCM washes were set aside, and the acid sol'n
basified w/ 25% NaOH until cloudy white ppt. remains. pH
confirmed w/ bromothymol blue.
Sol'n. extracted w/ 3 x 25 ml. DCM. The aqueous sol'n.
was set aside, the DCM extracts washed w/ 1 x 20 ml. H2O,
2 x sat. NaCl sol'n. dried w/ MgSO4, stripped of DCM by
boiling off, til nearly gone then adding 25 ml. Toluene.
about 6 drops of H2O were added, then 1 drop of
bromoythymol blue as indicator. Conc. hcl was then
dripped in by eyedropper, with swirling. the small
aqueous layer changes from 'darkish' to light yellow w/
each additon and back to dark w/ swirling. Also, as the
'drop' of acid at the tip of the dropper approaches the
surface of the tolune mix, 'smoke' (ammonium chloride)?
appears above the surface. As the end point approaches,
this effect disapears, and the aq/ layer stays bright
yellow. stir and swirl vigorously, to ensure all base has
reacted, then place on heat. boil off all the tolune,
which should distill most of the water. when the temp of
the beaker rises, (above 110^C) a slight smoke should
appear as the toluene vapour ends. remove quickly from
heat, cool and add an equal volume of cold dry acetone,
followed by a similar amt. of etO2 (also dry and cold).
place beaker in dish filled w/ snow (got surplus), and
stir vigorously. In moments, the layers should cease, and
a pinkish 'mush' occurs. stirr abit longer, add a bit
more acetone, stir, decant, repeat. transfer to buchner,
add acetone, stir, and filter. reapeat til snow white.
yeild of snow white product from 4.5gm ketone, 3 gms.
(plus ~200 mg dirty white stuff).
All of the 'process' solutions were retained, and
appropriate extractions done, and minimal product
recovered.
The extraction of the entire Al sludge provided an
exceptionally easy and tidy cleanup. Instead of spending
several hours filtering and re-filtering, the stuff went
from rxn vessel to xtals under 1.5hrs.
performing the acid/base routine has two advantages.
1. it removes any non-basic materials, such as unreacted
ketone, iso alkene, aldehydes etc., when the acid
extraction is washed w/ polar solvent.
2. it removes the base from the relatively large volume
of tolune used to extract it from the Al/sludge, and
allows the amt. of solvent boiled off to be kept to a
minimum.
3. It provides another level of purification from the
insidious mercury toxin.
Thanks to Ritter for his amalgam extraction, and to
sunlight for his toluene xtallization tip. This is a
great combination which takes a lot of the drudge out of
Al/Hg reduction, & workup.
Now all Elton's roadie's dead uncle has to do is improve
ketone prep.
This ? is off topic, but anyways,...
during the hydrolysis stage of performic, no mention is
made of stirring. early exps. never stirred during acid
hydrolysis reflux. the oil kinda swirled and bobbed and
the dil acid boiled. last time, mag stirring was applied
about 1/2 way and the mix changed character. w/o
stirring, it was basically clear. after stirring (and
heating) for another 1.5 hrs., the acid stayed 'red'!
even after sitting in the cold for many hours. some
miscibility occured w/ stirring that didn't without!
trying to find the point(s) in this process where the
yeild goes to shit. isoalkene was twice distilled @ atm,
pressure and 248-252^C.
Formic acid was concentrated from 65% to >80% by repeated
treatment w/ anhydrous copper sulfate followed by
distillation.
SG went from 1.170 to 1.195. H2O2 was 35%
40ml acetone used as solvent w/ 32.4gms. isoalkene.
anybody got the SG of 80, 88 and 90% formic (at 20^C of
course)
dpHarma