Preparation method of 2, 2, 6, 6-tetraethyl-3, 5-heptanedione
A technology of heptanedione and tetraethyl, which is applied in the field of preparation of 2,2,6,6-tetraethyl-3,5-heptanedione, can solve large steric hindrance, is difficult to purify and synthesize Low yield and other problems, to achieve the effects of cost saving, convenient industrial operation, and simple synthesis route
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Embodiment 1
[0027]
[0028] Put 208g of malonic acid (2.0mol), 2.5g of N,N-dimethylformamide and 1000mL of dichloroethane into the reaction flask and mix, control the room temperature to 20~30℃, add dropwise 832.8g of thionyl chloride (7.0 mol), after the dropwise addition was completed, the temperature was raised to 60-65° C. for 8 hours, and no raw materials were detected by GC. Concentrate under reduced pressure, replace with toluene to remove thionyl chloride, and distill to obtain 215.7 g of malonyl chloride, yield 76.5%, GC: 98.8%.
[0029]
[0030] Put 208g of malonic acid (2.0mol), 2.4g of pyridine and 800mL of toluene into the reaction flask to mix, control the room temperature to 20-30°C, add 634.65g of oxalyl chloride (5.0mol) dropwise, and raise the temperature to 70-75°C after the dropwise addition After reacting for 6 hours, GC detected that there was no remaining raw material. Concentrate under reduced pressure, replace with toluene to remove phosphorus oxychloride, ...
Embodiment 2
[0033]
[0034] Under the protection of nitrogen, put 99.5g of dimethylhydroxylamine hydrochloride (1.02mol) and 900mL of dichloromethane into the jacketed reaction bottle, stir well and cool down to -30~-25°C, add 70.5g of malonyl chloride (0.5mol) , control the temperature at -30~-25°C, add 232.7 triethylamine (2.3mol) dropwise, react for 2 hours after the dropwise addition, GC detects that there is no raw material remaining, add 2% hydrochloric acid to adjust pH=2-3, separate layers, organic The phase was washed with 5% aqueous sodium bicarbonate solution, and then washed with water, the enriched organic phase was concentrated, and n-heptane was added to precipitate the solid, filtered and dried to obtain N,N'-dimethoxy-N,N'-dimethylpropane Diamide 84.6g, yield 89.3%, GC: 99.4%. 1 HNMR (400MHz, CDCl 3 ): 3.39(s,6H), 3.07(m,2H), 2.71(s,6H).
[0035]
[0036] Under nitrogen protection, put 99.5g of dimethylhydroxylamine hydrochloride (1.02mol) and 900mL of butyl aceta...
Embodiment 3
[0039]
[0040] Under the protection of nitrogen, 76.1g of N,N'-dimethoxy-N,N'-dimethylmalonamide (0.4mol), B(C 6 f 5 ) 3 (20.5g, 0.04mol) and 380mL tetrahydrofuran, lower the temperature to -20°C, and add 560mL 1.5mol / L 3-methylpentane magnesium chloride tetrahydrofuran solution (0.84mol) dropwise at this temperature, and slowly heat up to 0°C, react for 1 hour, add dropwise 2% hydrochloric acid aqueous solution to quench, extract the aqueous phase with ethyl acetate, combine the organic phases to concentrate, heat up and distill under vacuum, collect fractions at 145-150°C, and obtain 2,2,6,6 - 80.2 g of tetraethyl-3,5-heptanedione, light yellow transparent liquid, GC: 99.1%, yield 83.4%. For specific HNMR data, see the appendix figure 1 .
[0041] Under the same conditions, when there is no catalyst, the reaction time is 10 hours, and the yield is 57.2%.
[0042]
[0043] Under nitrogen protection, 76.1g of N,N'-dimethoxy-N,N'-dimethylmalonamide (0.4mol), B(C 6 ...
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