Having mild success with O2/IPA wackers, it was decided that the rxn was too tempermental (personally) and not sufficiently scalable, so the buff performic was chosen.
Following LabTop and Baalchemist write ups, all seemed well until the acid hydrolysis stage.
What follows is a brief account, for which criticism and advice is sought.
236 ml vac dist alkene (saf) converted to isoalkene by vac reflux overnight with 5.2 g KOH (all water removed by venting to atmosph for 30 mins).
then 225 ml isoalkene placed in 2L 3-neck rb, followed by 76.9g NaCOH3 and 770 ml DCM.
Prepared 384.5 g (317.8 ml) 88% formic acid and 235 g (166.3 ml) Fresh 35% H2O2. CHilled same.
Began dripping performic in at a rate that kept temp under 40 C. required approx 7 hours for this size batch.
Color converted from clear to yellow to orange juice after all performic added. Stirred for total of 24 hrs.
Two layers formed, sepped off bottom, washed aq layer with DCM, pooled extracts, vapped off DCM at atmosph to collect Monoformyl glycol as thick orange syrup --325 ml
HERE IS WHERE THE ERROR MAY HAVE OCCURRED:
Did not have vessel of sufficent size for hydrolysis as shown:
2768 g 15% H2SO4 [diluted 227.9 ml 99% H2SO4 with 2353ml H2O ( 0.1515 x 2768g =428g H2SO4 / 1.84 =227.9 ml)]
This quantity didnt fit in the 2L RB, so the reactants were divided into 2/3 and 1/3 batches (first mistake: it should have been 1/2 and 1/2 ) . The 2/3 batch 216 ml glycol was preheated to 80 C and the acid 1717 ml preheated to 80 C.
Added acid to glycol and stirred heavily for 2 hours keeping temp between 75-80 C. There was clearly too much in the flask, so stiring was not as it should have been.
The glycol stayed primarily on the bottom and was distinctively separated from the acid ( as in oil/water combo) throughout the rxn.
The layers separated immediately on stopping and sepped apart easily.
The second batch was processed with 109 ml glycol and 858 ml acid.
THe stirring was much better. THe 2 layers separated immediately as well.
Both extracts were pooled, the aq layers wsahed with DCM and the DCM vapped off, extracts pooled.
washed with 5% bicarb to neutralize ( was actually still slightly acidic when done )
Distilled the suspected raw ketone as follows:
Vac pulls 9 torr perfectly. Alkene comes over at 90 and the isolalkene at 100.
Preheated oil bath to 125C , placed ketone in 500 ml rb and then in oil bath. applied vac. It stabilized qiuckly. Raised temp steadily. When oil hit 150 C the dist temp read 50 C. Oil read 158 C the dist temp hit 119 C and a large fraction came over in 1.5 hours (78 mls).
Temp dropped sharply , so flasks were switched.
Temp rose to 124-125 C and another fractio came over (78 mls)
The first fraction was pale yellow in color, a viscous oil with a definite NOT Saf smell.
The second fraction was best described as flourscent green--a yellow color with a distinct vivd green mixed in.
It also smelled quite similar, and had a viscous nature.
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Can anyone discern what occured and why? Suspect that the hydrolysis was faulted in the first batch.
The suspected ketone seems to fit the descriptions found using the FSE, but why the 2 fractions so close together and with diff charactersitics? Is the second the ketone and the first...what?.. an incompletely hydrolized glycol?
If that is true, can the first distillation result be rehydrolysed and then distilled again to save it?
Bisulfite test will be performed on both and results posted, but any interim adivce will be greatfuuly appreciated.
The results will be applied to the wet reductive alkylation process once this issue is cleared up.
Full write ups will follow.
Thanks to all
