(RS)-3-Methyl-2-oxobuttersaeure 2-Oxoisovaleric acid 3-Methyl-2-oxobuttersaeure 3-Methyl-2-oxobutyric acid 3715-29-5 51828-94-5 759-05-7 Butanoic acid, 3-methyl-2-oxo- EINECS 212-065-4 alpha-Ketoisovalerate alpha-Ketoisovaleric acid