Yield:-

Reaction Conditions:

in dichloromethane at 20; for 0.5 h;

Steps:

1; 3-4 Example 1:

Put 300 g of D-mandelic acid, 100 g of formic acid, and 300 g of dichloromethane into a 2000 ml four-necked flask, and stir for half an hour to dissolve at room temperature. After dissolving, add 5g of activated carbon, cool to 0-10°C, and then drip a mixed solution of 195g and 300g of dichloromethane. Add dropwise at a temperature of 0-10°C, during which hydrogen chloride gas is precipitated. The dripping time is 3h. After the dripping is finished, keep the temperature at 10-20°C for 5 hours, filter the activated carbon, and recover the dichloromethane and excess formic acid under normal pressure. 350-360g of colorless viscous liquid D(-)formylmandelic acid is obtained. Put 300 g (1.97 mol) of D-mandelic acid, 100 g (2.17 mol) of formic acid, and 300 g of dichloromethane into a 2000 ml four-necked flask, and stir for half an hour to dissolve at room temperature. After dissolving, add 5 g of activated carbon, cool to 0-10°C, and then drop a hardened dichloromethane solution into the solution. The added amount of hardened light is shown in Table 3. The dropping temperature is 0-10°C, and hydrogen chloride gas is precipitated during the dropping, and the dropping time is 3h. After the dripping is finished, keep the temperature at 10-20°C for 5 hours, filter the activated carbon, and recover the dichloromethane and excess formic acid under normal pressure. The colorless viscous D(-) formylmandelic acid liquid was obtained. After calculation, when the added amount of solid light is 1.2mol, 1mol, 0.6mol, 0.4mol, The conversion rate of D-mandelic acid reached 99.9%, 99.9%, 99.8%, and 95.2% respectively. And considering the production cost, when the added amount of solid light is 1 mol, that is, when the molar ratio of added solid light to D-mandelic acid is 1:1.97, the effect is best. Put 300 g (1.97 mol) of D-mandelic acid, 300 g of formic acid, and dichloromethane into a 2000 ml four-necked flask. The amount of formic acid added is as shown in Table 4, and the mixture was stirred at room temperature for half an hour to dissolve. After dissolving, add 5g of activated carbon, after cooling to 010, keep the temperature at 1020 for 5 hours, filter the activated carbon, and recover dichloromethane and excess formic acid under normal pressure. The colorless viscous D(-) formylmandelic acid liquid was obtained. According to calculations, without adding solid light, when the added amount of formic acid is 2.17 mol, 10 mol, 20 mol, 30 mol, 50 mol, the conversion rate of D-mandelic acid reaches 50%, 65%, 75%, respectively. 85% and 92%.

References:

CN113354534,2021,A Location in patent:Paragraph 0032-0037; 0042-0055