(Master Searcher)
03-17-03 04:57
No 417860
(Rated as: excellent)
Here's some patents that disclose methods of methylenation of catechols using methylene dihalides such as methylene chloride.
Patent US3922285 methylenation of catechols with methylene chloride and strong bases
Patent US3436403 methylene chloride and highly polar aprotic solvents
Patent US2979513 mercaptohydroquinones
Patent US4082774 methylenation of catechol using methylene dihalides alkaline highly polar solvent (DMSO)
Patent US4183861 methylenation of catechols using methylene chloride and catalyst
Patent US5936103 N-methylpyrrolidone solvent
http://www.geocities.com/dritte123/PSPF.
The hardest thing to explain is the obvious
(Hive Bee)
03-20-03 18:38
No 419453
There is a variation on USP 4183861 involving a trace of iodine (or iodide) as an additional catalyst - only about a tenth of the mole ratio of the phase transfer catalyst. This is available as a Japanese patent but only the abstract is available as an English translation in Japanese Patent Abstracts.
(Master Searcher)
03-21-03 00:18
No 419580
What's the number?
http://www.geocities.com/dritte123/PSPF.
The hardest thing to explain is the obvious
(Hive Bee)
03-21-03 21:01
No 419883
This isn't it but it is related. I'm still looking.
Title: Production Of Methoxymethylenedioxybenzene
Patent Number: JP62061975
Publication date: 87-03-18
Inventor(s): Morita Yoshimi; others: 04
Applicant(s): Mitsubishi Chem Ind Ltd
Application Number: JP850201078 850911
Priority Number(s):
IPC Classification: C07D317/64; B01J31/02
Requested Patent: JP62061975
Equivalents:
Abstract
Purpose: To obtain the titled compound in high yield and easily, by reacting 1-methoxy-2,3-dihydroxybenzene with methylene bromide by the use of a quaternary ammonium salt or quaternary phosphonium salt as a catalyst in an alkali aqueous solution.
Constitution: In obtaining 1-methoxy-2,3-methylenedioxybenzene by reacting 1-methoxy-2,3-dihydroxybenzene with methylene bromide, the reaction is carried out in the presence of a quaternary ammonium salt or quaternary phosphonium salt shown by the formula (M is N or P; X is halogen; R<1>-R<4> are lower alkyl, aryl or aralkyl) (e.g., tetra-normal-butylammonium bromide, etc.,) in an aqueous solution of an alkali such as NaOH, etc., to give the aimed compound.
Use:An intermediate for organic syntheses of drugs, etc.
(Hive Bee)
03-21-03 21:15
No 419886
Acta Scientiarum Naturalium 1983, page 92-6, No. ? (but could be #2)
Synthesis of 1,3-Benzodioxole by Phase Transfer Catalysis
Zhao Yingying, Jia Hongbin, Li Xingfu, Liu Mingfang, Shen Yusheng
(Department of Chemistry, Jilin University)
Abstract: The 1,3-benzodioxole is synthesized in 80% yield by reaction of catechol with dichloromethane and aqueous potassium hydroxide under the catalysis of benzyaltriethylammonium chloride. The effect of reaction factors is discussed.
The main side reactions are found to be the formation of the dimer of 1,3-benzodioxole and the condensation of the catecholate with formaldehyde, which is formed by hydrolysis of dichloromethane in the strongly alkaline medium.
The article is in Chinese but I can make out an equation:
catechol + NaOH + DCM @ 110-115 C --> Benzodioxole
The temperature seems a little high to me.
(Hive Bee)
03-21-03 21:24
No 419891
The previous Chinese journal was was #2 and is AKA:
Jilin Daxue Ziran Kexue Xuebao 2, 92, (1983)
The Preparation of methylenedioxy derivatives.
Japan 046949-B, 1984. Takasago perfumery KK, 7 pages (Japanese)
Abstract: 1 mole of a 1,2-dihydroxy aromatic derivative such as catechol, 4-methyl-catechol, 4-propylcatechol, etc., is reacted with dichloromethane, (4 to 3 moles) in caustic alkali at 50 - 130C [9] using a quaternary ammonium or phosphonium salt as a phase transfer catalyst and, optionally iodine, an alkyl iodide or metal iodide as a promoter in an amount of 1/10 to 1/100 molar times based on the diphenol compound. The methylenedioxy compound can easily be prepared in high yield.
Details of PTC used;
R2
|
R1 - M+ - R3 X-
|
R4
(where M is N or P; X is Cl, Br, I; R1-4 are the same or lower aryl or alkyl) eg. tetramethyl ammonium, trimethylphenyl ammonium, tetramethyl phosphonium, trimethylphenyl phosphonium etc.
(Hive Bee)
03-21-03 21:33
No 419895
I obviously can't read japanese but some words are in English in a table. The tabulated results show 18 reactions (numbered 6 - 24). The yields vary from 61% to 96%. I have no idea what the compounds are. And I'm just guessing that the last column in the table (with a % sign in the heading) refers to the yield.
(Distinctive Doe)
04-03-03 07:42
No 423505
(Rated as: excellent)
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.
(Hive Addict)
04-14-03 06:23
No 426515
How should the procedures for expaple 1 and 4 be changed to account for not using an autoclave? Or would not using pressure cause the reaction to slow too much either causing a lot of byproducts or poor yields?
Like could the temperature and length of time be modified to take up for not using an autoclave or would the extended time/increase of temperature somehow damage the product/ reaction mix and produce bad results?
Yes, That pic really is me!
(Distinctive Doe)
04-14-03 06:59
No 426529
The problem is that DCM boils at such low temperatures. I don't think it would bee to hard to devise a safe system to do this in. Just make sure it has adequate headspace.
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.
2.4 atmospheres is only about 36psi, thats not very high a steel pipe would easily withstand such pressures, plus the temp is only 70C, not that high really.
(Hive Addict)
04-14-03 08:25
No 426551
Sorry I read that and saw 24 aptmospheres... I had contemplated using dmf as replacemt to raise reaction temp but can't remember where I saw a procedure for using dmf. Actually have some glass reaction vessels that can be used for that. Thanks... guess I better slow down the reading and concentrate more on gettin the details straight before posting. I have been cramming way too much research into too many areas in too little time. But thanks foxy...
Yes, That pic really is me!