The reaction of an aromatic heterocycle with a proton is called a protonation. One of articles about this theory is 《A disregarded complication in the synthesis of β-keto esters by the base-catalyzed acidolysis of diethyl acylmalonates》. Authors are Brandstrom, Arne.The article about the compound:2,6-Dimethyl-3,5-heptanedionecas:18362-64-6,SMILESS:CC(C)C(CC(C(C)C)=O)=O).Application of 18362-64-6. Through the article, more information about this compound (cas:18362-64-6) is conveyed.
cf. preceding abstract The main impurities in the preparation of β-keto esters from di-Et malonates according to the reaction RCOCH-(CO2Et)2 + RCO2H → RCOCH2CO2Et + RCO2Et + CO2 were studied. EtCOCH2CO2Et (I) was synthesized (preceding abstract). Fractionation gave 47 g. forerun, b7.5 40-68°, which with Cu(OAc)2 solution yielded the Cu derivative, m. 212°, of (EtCO)2CH2 (II), corresponding to 31 g. II, b9 59°. The 2 following fractions, b7.5 68-9° and 72-3°. were considered to be the enol and keto forms of I. The residue consisted chiefly of CH2(CO2Et)2, b7.5 79-81° (10% of the initial products). The products from the reaction of Me2CHCO2H with Me2CHCOCH(CO2Et2 showed a 1% yield of (Me2CHCO)2CH2, isolated as its Cu salt, m. 129°. The products from the reaction of PrCO2H and PrCOCH(CO2Et)2 could not be separated by distillation, and 10 g. of the distilled product was refluxed 3 hrs. with 100 cc. 20% H2SO4and the product steam-distilled to give 11% (PrCO)2CH2 (precipitated as the Cu derivative, m 157°). Equimol. amounts of AcCH(CO2Et)2 and AcCH2CO2Et (III) were refluxed 3 hrs. with a little MgO and Cu(OAc)2, and the mixture fractionated; fraction 1, b7.5 30-60°, gave 1.5 g. AcCH2COMe; fraction 2, b7.5 60- 75°, contained 6 g. III; fraction 3, b7.5 75-83°, gave 22 g. CH2(CO2Et)2 (S-benzylisothiuronium salt, m. 147°); and fraction 4, 10 g., b7.5 83-100°, gave Ac2CHCO2Et.
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Reference:
Thiazole | C3H3NS – PubChem,
Thiazole | chemical compound | Britannica