Toluene → tert-butyl 2-hydroxyimino-3-oxobutanoate

To a mixture of tert-butyl alcohol [741.2 g] and 4-(dimethylamino)pyridine [6.1 g] was added dropwise diketene [840.7 g] at 50° to 60° C. in the course of one hour while stirring. The stirring was continued for one further hour at 30° to 50° C. To the colorless and clear reaction mixture thus obtained was added acetic acid [1501 g]. To the resultant solution was added dropwise a solution of sodium nitrite [773.2 g] in water [1.35 l] at 5° to 9° C. in the course of 1.5 hour, followed by stirring for 1.5 hour at 8° to 18° C. To the reaction mixture were added toluene [1.42 l ] and a 5% aqueous solution of sodium chloride [1.3 l ], to which was then added sodium hydroxide [600 g] in water [1.1 l ] to render the pH to 6.7. The reaction mixture was separated into two layers, and the aqueous layer was subjected to extraction with toluene (0.7 l). The extract was combined with the toluene layer and washed with a 5% aqueous solution of sodium chloride (1.2 l), from which toluene was distilled off under reduced pressure to leave crude product of tert-butyl 2-hydroxyimino-3-oxobutyrate as a viscous oily substance.

1. customwas continued for one further hour at 30° to 50° C
2. customTo the colorless and clear reaction mixture thus obtained
3. stirringby stirring for 1.5 hour at 8° to 18° C
4. customThe reaction mixture was separated into two layers
5. extractionthe aqueous layer was subjected to extraction with toluene (0.7 l)
6. washwashed with a 5% aqueous solution of sodium chloride (1.2 l), from which toluene
7. distillationwas distilled off under reduced pressure

ORD record

ord-65052a66f29d4123ad2ab62bf33f4604

Source dataset

uspto-grants-1993_02

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US05183929