|
2,6 - dimethyl chromanone is an important starting materials and pharmaceutical intermediates, often in the pharmaceutical industry, and its various derivatives as antibacterial agents, intermediates of anticancer drugs and antiallergic drugs, but also as starting materials of synthetic perfumes, dyes, and herbicides. 2,6 - dimethyl-pyrone does not exist in nature, natural product, and must be obtained by synthesis. U.S. Patent No. 2,6 - dimethyl pyrone conditions more demanding and more byproducts This thesis of 2,6 - dimethyl-pyrone, separation and purification, qualitative and quantitative analysis. Acetyl acetone and methyl acetate in accordance with the reaction mechanism, as the raw materials, the effects of the kind and amount of the catalyst on the yield, the amount of reactants, reaction temperature and time, the organic solvent and the extraction agent. Obtained by an experiment with the following conclusions: to alkaline sodium ethoxide as catalyst, acetylacetonate: acetate: sodium ethoxide = 1:2.5:2 (molar ratio), as the reaction medium in an aprotic polar solvent such as tetrahydrofuran, the reaction temperature was 85 ° C, the reaction time of 6 h, ether as extractant, 13.35% of the maximum yield of 2,6 - dimethyl-pyrone. Pyranone reaction system of the 2,6 - dimethyl 2,6 - dimethyl chromanone and acetylacetone analysis method. Its qualitative infrared and nuclear magnetic resonance spectroscopy, qualitative and quantitative analysis with high-performance liquid chromatography. HPLC analysis conditions: Eclipse XDB-C18 column (150 mm ⅹ 4.6 mm, 5μm); Mobile phase: tetrahydrofuran - water (20:80, v / v) plus 0.5% sodium dihydrogen phosphate, and 0.5 % hydrogen phosphate, disodium (pH = 5); flow rate of 0.6 mL / min; UV detection at a wavelength of 240 nm; column temperature of 30 ° C; injection volume 3 μL. HPLC analysis under the conditions established, 2,6 - dimethyl-pyrone and acetylacetone linear relationship good correlation coefficient of 0.9999, and a wide linear range, 2,6 - methyl pyrone linear interval of 0.01 ~ 200.3 mg / L, acetylacetone as 0.01 to 50.68 mg / L. 2,6 - dimethyl-pyrone and acetylacetone chromatographic peak area RSD RSD between 0.40 to 1.65%, retention time between 0.45 to 0.89%, the average recovery rate in the range of 98.34 to 102.51% RSD values ??were less than 1.0%. Within 15 min, acetylacetone and 2,6 - dimethyl-pyrone content can be analyzed simultaneously. Establish a new process route of synthesis of 2,6 - dimethyl-pyrone, the raw material used is easy to get, and the price is low, mild reaction conditions, despite the problems of low yield, but the method is feasible for the future establishment of a low-cost, high The yield of 2,6 - dimethyl pyrone synthesis route; established analytical method is highly sensitive, accurate, reliable, not only suitable for the quantitative determination of 2,6 - dimethyl-pyrone and acetylacetone , and acetylacetonate system can be used to take the 2,6 - dimethyl chromanone reaction process the tracking and detection of the reactants and each of the intermediate compounds, and provides a fast and efficient analytical method for the control of the reaction process, and their synthesis process conditions optimization has guiding significance.
|