Method for producing methylene-1,3-dioxolanes
View Patent ↗The present invention relates to a novel method for preparing methylene-1,3-dioxolanes of the general formula (I) in which R 1 and R 2 have the meanings stated in the description. Methylene-1,3-dioxolanes are important intermediates for preparing pyrazoles and anthranilic acid amides, which may be used as insecticides.
1. Method for preparing methylene-1,3-dioxolane of formula (I),
where
R 1 and R 2 independently of one another are hydrogen, alkyl, aryl or alkylaryl,
R 1 and R 2 may also form, together with the carbon atom to which they are linked, a 4- to 7-membered, saturated, optionally substituted ring,
comprising reacting a compound of formula (II),
where
R 1 , R 2 have the meanings stated above,
X is halogen,
with one or more inorganic bases in the presence of one or more polyethylene glycol dimethyl ethers or polyethylene glycol diethyl ethers.
2. Method for preparing a compound formula (I) according to claim 1 , wherein
R 1 and R 2 independently of one another are hydrogen, (C 1 -C 12 )-alkyl, pentamethylene or hexamethylene,
X is chlorine or bromine.
3. Method for preparing a compound formula (I) according to claim 1 , wherein one or more of NaOH, KOH, NaO t Bu, KO t Bu, NaOMe or KOMe is used as inorganic base.
4. Method for preparing a compound of formula (I) according to claim 1 , wherein one or more polyethylene glycol dimethyl ethers or polyethylene glycol diethyl ethers having a molar mass of 200 to 500 are used.
5. Method for preparing a compound formula (I) according to claim 1 , wherein 1 mole of a compound of formula (II) is reacted with 0.8 mole to 2.5 moles of an inorganic base.
6. Method for preparing a compound of formula (I) according to claim 1 , wherein the method is carried out in a temperature range from 60° C. to 150° C.