Acetone Cyanohydrin → 2-(2-hydroxyprop-2-yl)-4,4,6-trimethyl-5,6-dihydro-4H-1,3-oxazine

Beteiligte Stoffe

Reaktionsschritte

To a 250 ml 3-necked flask with a thermometer, a mechanical stirrer, and a 100 ml addition funnel attached was added 200 ml of concentrated H2SO4. The acid was cooled to 0°-5° C. with a dry-ice/acetone bath while 51 g (0.6 mole) of the acetone cyanohydrin was added at such a rate so as to maintain the temperature in the -10° to 10° C. range (Note--caution must be exercised in the initial stages of the addition since a vigorous exotherm occurs). After the addition of the nitrile, 59.0 g (0.5 moles) of 2-methyl-2,4-pentanediol was added again at a rate that kept the temperature in the -10° to 10° range (see the previous note). The mixture was stirred for an additional one hour then poured onto crushed ice (~5° C.). The acidic aqueous solution was then extracted twice with ether and the ether layers discarded. The acidic aqueous layer was then poured into a large beaker which contained ~400 g of NaHCO3 and ether. The beaker was cooled with an ice-water bath and was not allowed to rise pass 36° (basification with aqueous KOH resulted in more extensive decomposition due to the higher temperature attained). The ether layer was dried over K2CO3 and concentrated. The residue obtained was distilled at 43° C. (0.5 mm) to yield 24 g (0.13 mole, 26%) of product. The structure of this alcohol was confirmed by I.R. and N.M.R.

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