Реакция #5248

Уравнение реакции

sulfuric acid

1,4-dichloro-2,3-butanediol

trioxane

1,4-dichloro-2,3-butanediol

→

4,5-Dichloromethyl-1,3-dioxolane

Выход 89.5%

Растворители

1,2-dichloroethane

Условия реакции

Обработка

1. 1
   ДругоеA three-neck 500-mL flask equipped with a thermometer, a mechanical stirrer, an addition funnel, a condenser
2. 2
   workup.ADDITIONDuring the addition period
3. 3
   Другоеthe flask was immersed in an ice bath
4. 4
   Температураto maintain the reaction temperature at 21.5° C. to 25.5° C. for 2.1 hours
5. 5
   ДругоеThe acid layer was removed
6. 6
   Промывкаwashed once with 30 mL EDC
7. 7
   ДругоеThe combined EDC solutions were quenched with 2% NaHCO3 (600 mL)
8. 8
   Промывкаwashed with deionized water (400 mL), 1% NaHCO3 solution (400 mL), deionized water (400 mL

Методика

A three-neck 500-mL flask equipped with a thermometer, a mechanical stirrer, an addition funnel, a condenser, and a positive nitrogen atmosphere was charged with 1,4-dichloro-2,3-butanediol (50.0 g, 0.314 mole), trioxane (9.43 g, 0.314 mole), and 1,2-dichloroethane (EDC) (300 mL). The 1,4-dichloro-2,3-butanediol was not totally dissolved. Concentrated sulfuric acid (46.3 g, 0.455 mole) was then added dropwise over eight minutes. During the addition period, a slight exotherm was noticed and the flask was immersed in an ice bath to maintain the reaction temperature at 21.5° C. to 25.5° C. for 2.1 hours. The reaction mixture was permitted to settle overnight. The acid layer was removed, washed once with 30 mL EDC, and discarded. The combined EDC solutions were quenched with 2% NaHCO3 (600 mL), washed with deionized water (400 mL), 1% NaHCO3 solution (400 mL), deionized water (400 mL, twice), and stripped in vacuo. The resulting light yellow liquid weighed 48.9 g (89.5% yield), and contained 1.8% EDC and 98.2% dl- and meso-(4,5-dichloromethyl)-1,3-dioxolane, as determined by GC analysis and proton NMR (CDCl3) δ (s, --OCH2O--), 4.1 (m, ClCH2CHCHCH2Cl), 3.6(d, ClCH2CHCHCH2Cl).

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