Rhodium
(Chief Bee)
11-13-02 22:48
No 379552
      Safrole Epoxidation: H2O2/PTC/Pertungstate
(Rated as: excellent)
    

This could be interesting on safrole. The epoxide is then rearranged to MDP2P with a mild lewis acid.

../rhodium/pdf /h2o2.terminal.epoxidation-1.pdf
../rhodium/pdf /h2o2.terminal.epoxidation-2.pdf

Synthesis of the co-catalyst aminomethylphosphonic acid:

Aminomethylphosphonic Acid
Synthesis 547-548 (1989) (../rhodium/pdf /aminomethylphosphonic.synthesis.pdf)


 
Phosphorus(III)chloride (8,75 mL, 0.10 mol) is added dropwise to well stirred mixture of 1,3,5-tripropanoylhexahydro-1,3,5-triazine (4c; 9.0 g, 0.035 mol) in acetic (or propionic) acid (40 mL) at 20C. The mixture is then heated on a water bath until acetyl (or propionoyl) chloride has been distilled of and then 30 min more. The oily residue is treated with 8 M aqueous HCl (50 mL) and refluxed overnight. The hydrolysate is evaporated under reduced pressure on a boiling water bath. The residue is dissolved in boiling water (20 mL) and then MeOH (100 mL) is added gradually to induce crystallization of product 3. The pH of the crystallizing mixture is adjusted to 5-6 by the addition of methyloxirane or pyridine. The resultant mixture is stored in the refrigerator overnight. The crystalline crude product 3 is isolated by suction, washed with MeOH, and dried 24h at room temperature. This product (10-11g) is dissolved in boiling water (20 mL) and crystallization is induced by the gradual addition of MeOH (50 mL). The crystallization mixture is stored in the refrigerator overnight The precipitated product 3 is isolated by suction, wasted with MeOH/H2O (2:1), and dried 24 h; yield: 7-8g (75-80%); mp 335-342C (dec).

1,3,5-Triacetylperhydro-sym-triazine (3, R = CH3)
Synthesis 467-468 (1976) (../rhodium/pdf /aminomethylphosphonic.precursor.pdf)



Water (1.8 mL) was azeotroped from p-toluenesulfonic acid (17.2g reagent grade MCB) in benzene (100 mL). Gravimetric analysis of the p-toluenesulfonic acid indicated nil sulfuric acid content. The solution was cooled to room temperature and acetonitrile (143.5, 3.5 mol) followed by 100% sulfuric acid (0.3g) was added. The solution was brought to reflux and a solution of trioxane (101.4g, 1.12 mol) benzene (200 ml), and acetic anhydride (27.4g, 0.26 mol) was added over a one hour period. The solution was refluxed an additional hour, cooled, and filtered. The white precipitate was washed with benzene to give the product in 61% yield, mp 95-97C.
 
 
 
 
    GC_MS
(Hive Bee)
11-13-02 23:44
No 379567
      similar     

I have a similar document for quite some time, but never tested it.

K Sato, M Aoki, M Ogawa, T Hashimoto, R Noyori. A practical method for epoxidation of terminal olefins with 30% hydrogen peroxide under halide-free conditions. J Org Chem 61(23) (1996) 8310-8311.

Bought chems: Na2WO4.2H2O, H2O2 30%, toluene, dimethylsulfate, tri-n-octylamine.
Self-synthesized chems: methyltri-n-octylammonium hydrogensulfate,(aminomethyl)phosphonic acid (according to the authors, it can be synthesized inexpensively following these two articles (which are for free themselves wink ): a. DJ Tracey, Synthesis (1976) 467-469; b. M Soroka, Synthesis (1989) 547-548.).
Tested for 1-octene, 1-decene and 1-dodecene. Yields are generally in the 90s %.
When I read the article, I had more the intention to check out its possibilities for styrene analogues (in synthesizing PEAs). Never went further than building some theoretical notes and calculations, which - I think - is a shame blush.

Ave Hive, synthetisandi te salutant!
 
 
 
 
    Rhodium
(Chief Bee)
11-14-02 13:25
No 379710
      Only $3.30 to epoxidize 162g Safrole!     

Great articles you found there! I linked them all from my post at the top of the thread. Now we only need a volunteer who adapts the procedure for safrole.

I really like one of the footnotes in the JOC article, which should appeal to all the people whining about palladium prices:

"The cost of the reagents used for the oxidation of 1 mol of olefin is only $3.30".
 
 
 
 
    Polverone
(Hive Bee)
01-07-03 00:13
No 396064
      Enhanced OTC-ness
(Rated as: excellent)
    

While searching for a way to dissolve tungsten without HNO3/HF mixture, I found the following interesting tidbit:


The dissolution of tungsten by hydrogen peroxide is little known... Consequently, when it was recently observed that commonly encountered commercial tungsten products such as powder, wire, and sheet are completely dissolved in 30% hydrogen peroxide within minutes to hours, it was thought that these findings should be reported because of their interesting implications for both analytical and inorganic chemistry, and for metallurgy.

...

The rate of dissolution was observed to increase with temperature; however, at temperatures above 60 degrees Celsium, an increasing rate of spontaneous decomposition tended to slow the reaction. Approximately 60 degrees C was found to give the most rapid dissolution.

...

Tungsten may be converted into various of its compounds via dissolution in hydrogen peroxide. Evaporation of the solution and drying at not over 100 degrees C produces yellow crystalline pertungstic acid which is freely soluble in hot water. Higher drying temperatures (ca. 180 degrees C and higher) convert the pertungstic acid to tungstic acid, or anhydrous tungsten trioxide, wich may be reacted and dissolved in accordance with their known properties. Alternatively, the alkali tungstates may be produced by addition of alkali hydroxide to the pertungstic acid solution, followed by boiling to expel both the free and combined hydrogen peroxide.




One could presumably fail to boil the solution mentioned above to recover sodium pertungstate instead of sodium tungstate. The authors found that 5 mil tungsten wire dissolved in 30% H2O2 at 60 degrees C in 1 1/2 hours, 10 mil wire took 2 1/3 hours, 15 mil wire 2 3/4 hours, 25 mil wire 3 hours. I'm not sure that the 1 mm tungsten TIG electrode sitting in 27% H2O2 here is ever going to show substantial dissolution, but I can hope. And if that doesn't work then I can always try burnt-out lightbulb filaments. I realize that it's probably simpler and easier to order sodium pertungstate, but it's always nice to be able to do it yourself.

Dissolution of Tungsten by Hydrogen Peroxide
P. C. Murau;
Anal. Chem. ; 1961; 33(8); 1125-1126.


19th century digital boy
 
 
 
 
    Rhodium
(Chief Bee)
12-03-03 09:48
No 474503
      Simplified epoxidation (catalyst made in situ)
(Rated as: excellent)
    

Method for making cycloaliphatic epoxides
Patent US6084111 (2000)
Patent US5767150 (1998)

The new method involves low level of catalyst composition and no organic acid and/or peracid, which results in simple product workup and process. The present invention uses hydrogen peroxide in the presence of

(a) tungstic acid or its metal salts,
(b) phosphoric acid or its metal salts,
(c) at least one phase transfer catalyst.

The epoxidation of unsaturated cyclic substrates with hydrogen peroxide in the presence of tungsten catalyst, phosphoric acid or its salt, and phase transfer catalyst can be performed at any temperature which is sufficient to react, however, particularly suitable temperatures are between 0C. and 100C., preferably from 25C. to 70C. The reaction takes place faster at higher temperature and requires shorter time to complete. The reaction is typically exothermic. Slow addition of hydrogen peroxide is preferred to control the exotherm. The reaction can be performed at pressures from subatmospheric to superatmospheric; however, the reaction is preferably carried out at atmospheric pressure.

The epoxidation can be performed with or without solvent. Solvent can be used to reduce the viscosity. If solvent is needed, water immiscible organic solvents such as chlorinated hydrocarbons, ethers, glycol ethers, hydrocarbons, combinations thereof, can be used. Particular suitable organic solvents are toluene, chlorobenzene, chloroform, methylene chloride, and the like.

Hydrogen peroxide solution is used as oxidant in the concentration of 5 to 70%. The amount of hydrogen peroxide can vary depending on the desired degree of epoxidation, typically from 0.1 to 1.5 equivalent per unsaturated double bond.

The phase transfer catalyst can be used from 0.001 to 1, preferably 0.05 to 0. 1, equivalents per equivalent of carbon--carbon double bond. Suitable phase transfer catalysts includes quaternary ammonium salts, quaternary phosphonium salts, and polyethers.

Phosphoric acid or its various salts can be used from 0.001 to 0.5 equivalents per equivalent of carbon-carbon double bond. Sodium or potassium salts of monobasic, dibasic, or tribasic salts of phosphoric acid can also be used. The final pH can be adjusted by other acids or bases to 0-5.

Tungsten catalysts can be used from 0.001 to 50% by weight based on the cyclic substrates. Tungstic acid or its metal salts can be used as the metal catalysts, the metal salts are water soluble and the acid is not. The typical catalyst is used from 0.005 to 1% and the preferred catalyst is tungstic acid which is not water soluble. Either tungstic acid which is not water soluble or its metal salts which are soluble can be used as the metal catalyst. The typical catalyst is used in amounts of about 0.005 to 1%, based on weight of unsaturated compound. The preferred metal catalyst is tungstic acid.

The expoxidation can be performed with or without solvent. The use of solvent is preferred because it reduces the viscosity. If solvent is desired, a water immiscible organic solvent such as chlorinated hydrocarbons, and ethers, glycol ethers, hydrocarbons, and combinations thereof, are especially useful. Particularly suitable organic solvents are toluene, chlorobenzene, chloroform, methylene chloride, heptane, and the like.

The method of the invention allows use of a low level of catalyst composition free of organic acid and/or peracid, resulting in simple product workup and process, and using readily available catalysts.


Example 2

Preparation of Diepoxide from Unsaturated Diester (epoxidation of a compound containing two cyclohexene rings bound together by a ester function)

Product from Example 1(100.0 g) was added to a reactor, followed by tungstic acid (0.80 g), phosphoric acid (85%, 0.40 g), sodium hydroxide (25%, 0.40 g), Aliquat 336 (0.80 g), and toluene (200.0 g). The mixture was stirred and heated to 50C. when slow addition of hydrogen peroxide (30%, 65.0 ml) began. The hydrogen peroxide addition was completed in 70 minutes to control the exotherm. The reaction mixture was kept at 50C. for 2.5 additional hours when no residual starting material was detected by GC and FTIR.

The final mixture was separated into two phases. The organic phase was isolated and washed twice with 50 ml of water to remove the excess hydrogen peroxide. The final dicycloaliphatic epoxide was isolated by removing solvent at 95C. under reduced pressure which has epoxy equivalent weight of 280.1 g/eq (yield 94.0 g).

Example 4

Preparation of Diepoxide from Unsaturated Dicyclic Diester (epoxidation of a compound containing two cyclohexene rings similar to the above)

Unsaturated dicyclic diester from Example 3 (100.0 g) was added to a reactor, followed by tungstic acid (0.80 g), phosphoric acid (85%, 0.40 g), sodium hydroxide (25%, 0.40 g), Aliquot 336 (0.80 g), and toluene (200.0 g). The mixture was stirred and heated to 50C. when slow addition of hydrogen peroxide (30%, 70.0 ml) began. The hydrogen peroxide addition was completed in 40 min to control the exotherm. The reaction mixture was kept at 50C. for 2.0 additional hours when no residual starting material was detected by GC and FTIR.

The final mixture was separated into two phases, the organic phase was isolated and washed twice with 50 ml of water to remove the excess hydrogen peroxide. The final dicycloaliphatic epoxide was isolated by removing solvent at 95C. under reduced pressure which has epoxy equivalent weight of 207.0 g/eq (yield 105.0 g).
 
 
 
 
    Rhodium
(Chief Bee)
04-18-04 11:18
No 501494
      Epoxidation with 30% Hydrogen Peroxide
(Rated as: excellent)
    

Here is another article by the group behind the articles in the first post in this thread:

A Halide-Free Method for Olefin Epoxidation with 30% Hydrogen Peroxide
Kazuhiko Sato, Masao Aoki, Masami Ogawa, Tadashi Hashimoto, David Panyella, and Ryoji Noyori
Bull. Chem. Soc. Jpn, 70, 905915 (1997) (../rhodium/pdf /h2o2.solvent-free.epoxidation.pdf)

Abstract
A catalytic system consisting of sodium tungstate dihydrate, (aminomethyl)phosphonic acid, and methyltrioctylammonium hydrogensulfate, effects the epoxidation of olefins using 30% hydrogen peroxide with a substrate-to-catalyst molar ratio of 50500. The reaction proceeds in high yield without solvents, or, alternatively, with added toluene under entirely halide-free conditions. Lipophilic ammonium hydrogensulfate, which replaces the conventional chloride, and an (-aminoalkyl)phosphonic acid are crucial for the high reactivity. This method is operationally simple, environmentally benign, and much more economical than the oxidation with m-chloroperbenzoic acid, allowing for a large-scale preparation of epoxides. Various substrates including terminal olefins, 1,1- and 1,2-disubstituted olefins, cyclic olefins, and tri- and tetrasubstituted olefins as well as allylic alcohols, esters, ,-unsaturated ketones, and ethers can be epoxidized in high yield. The scope and limitations of this new reaction system are discussed.

The Hive - Clandestine Chemists Without Borders
 
 
 
 
    Nicodem
(Hive Bee)
04-19-04 03:14
No 501602
      ../rhodium/pdf /XXX.pdf     

Rhodium, could you please correct the link for the PDF above so I can download it. Thanks.

The real drug-problem is that we need more and better drugs. J. Ott
 
 
 
 
    Rhodium
(Chief Bee)
04-19-04 04:33
No 501606
      Duh. :-S It works now.     

Duh. crazy It works now.

The Hive - Clandestine Chemists Without Borders