Patent US3838051
OLD methylation reference
Patent US3726924
Methyeneation and prep of strong base(trisdimethlyaminomethane)
Here is one of the patents listed by PE SAM
Patent US4183861
--------------------------------------------------------------------------------
Process for preparing aromatic methylene-dioxy compounds
EXAMPLE 1: METHYLENEDIOXYBENZENE:
Methylene chloride (100 ml., 1.56 moles), tetrabutylammonium bromide (6.42 g., 0.02 moles) and water (200 ml.) are placed in an autoclave. To this mixture is added a total of 15 g. pyrocatechin (0.1362 moles) and sodium hydroxide (15.9 g., 0.3975 moles) in flake form in successive stages.
The reaction temperature is maintained at 70.degree. C. and the pressure within the autoclave rises to a maximum of 2.4 atmospheres. The reaction is completed within three hours.
After the reaction is completed, the organic phase is separated and excess methylene chloride is distilled off and recycled. Pure methylenedioxybenzene (13.8 g.; 83% yield) is obtained by distillation.
Tetrabutylammonium bromide remains as a distillation residue and this material can be recovered and reused as a catalyst to produce additional product.
By substituting pyrocatechoic acid (ie., 2,3-dihydroxybenzoic acid) for the pyrocatechin of Example 1, and otherwise following the procedure described therein, the product 1-carboxy-methylenedioxybenzene is obtained.
EXAMPLE 2: METHYLENEDIOXYBENZENE:
By following the procedure described in Example 1, but substituting hexadecyltributyl phosphonium bromide for tetrabutylammonium bromide in an otherwise analogous process, 11.65 g. of methylenedioxybenzene (70% yield) is obtained.
EXAMPLE 3: 1-METHYL-3,4-METHYLENEDIOXYBENZENE:
Methylene chloride (1.56 g., 100 ml.) and tetrabutylammonium bromide (6.42 g., 0.02 moles) are placed in an autoclave, and to this mixture is added a total of 24.8 g. of 4-methylpyrocatechin (0.2 moles) and caustic soda (24 g., 0.6 moles) in flake form, with agitation, at 80.degree. C. The reaction is completed within five hours.
After the reaction is completed, the product is recovered by following the procedure described in Example 1, that is, the organic phase is separated, excess methylene chloride is distilled off and recycled and 1-methyl-3,4-methylenedioxybenzene (19.4 g.; 71.3% yield) is obtained by distillation.
EXAMPLE 4: PIPERONAL:
Methylene chloride (100 ml., 1.56 moles), tetrabutylammonium bromide (6.42 g., 0.02 moles) and water (200 ml.) are placed in an autoclave. A total of 27.6 g. of protocatechic aldehyde (0.2 moles) and caustic soda (24 g., 0.6 moles) in water (20 ml.) are then added to the autoclave in stages at a temperature of 70.degree. C.
The pressure within the autoclave increases to a maximum of 2.4 atmospheres and the reaction is completed within four hours.
The reaction mixture is allowed to cool to ambient temperatures and the organic phase is separated. Excess methylene chloride is recovered from the organic phase by distillation and high purity piperonal (21 g., 70% yield) is isolated. The product is identified by gas chromatography and infra-red spectrum analysis by comparing against a pure sample.
Upon substituting tetramethylarsonium chloride, for the tetrabutylammonium bromide of Example 4, and otherwise following the procedure described therein, an identical piperonal product is obtained.