YAMAMOTO KEISHI (JP)
MASHIMA KAZUSHI (JP)
TSURUGI HAYATO (JP)
UNIV OSAKA (JP)
TOKUYASU T ET AL: "Co(III)-Alkyl Complex- and Co(III)-Alkylperoxo Complex-Catalyzed Triethylsilylperoxidation of Alkenes with Molecular Oxygen and Triethylsilane", ORGANIC LETTERS, vol. 4, no. 21, 17 October 2002 (2002-10-17), pages 3595 - 3598, XP055533624, ISSN: 1523-7060, DOI: 10.1021/ol0201299
KILPATRICK M L ET AL: "The preparation of hydrogen peroxide", JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, vol. 48, no. 12, December 1926 (1926-12-01), pages 3019 - 3021, XP055533774, ISSN: 0002-7863, DOI: 10.1021/ja01691a003
CAMPOS MARTIN J M ET AL: "Hydrogen Peroxide Synthesis: An Outlook beyond the Anthraquinone Process", ANGEWANDTE CHEMIE INTERNATIONAL EDITION, vol. 45, no. 42, 27 October 2006 (2006-10-27), pages 6962 - 6984, XP055533786, ISSN: 1433-7851, DOI: 10.1002/anie.200503779
| Claims 1 . Method for obtaining peroxides of the general formula (I) R1 - O - O - R2 (I) wherein Ri, R2 can be the same or different, Ri, R2 being H, D(2H), T(3H), -Si (R3a, R3b, R3c)3, with R3a.R3b.R3c being H, substituted or unsubstituted linear or branched C1 -C5 alkyl, , R3a.R3b.R3c being the same or different, and O is 150, 160, 170 or 180, or a mixture thereof, by reacting a cyclodiene compound of the general formula (I la, b) wherein X being CH, CD, CT or N, R4 being -Si (R3a, R3b, R3c)3, with R3a ,R3b ,R3c having the above meaning, Rsa , R5b, R5C, R5d being H, D, T, substituted or unsubstituted linear or branched C1 -C5 alkyl, R5a , Rsb, Rsc, Rsd being the same or different; or wherein R5a, Rsb and R5c, Rsd can be part of a C6 aryl ring according to one of the following structures (III) or (IV): R7a-h being H, substituted or unsubstituted linear or branched C1 -C5 alkyl, and R7a-h being the same or different, R6 being -Si (R3a, R3b, R3c)3, with R3a ,R3b ,R3c having the above meaning in case of general formulae (lla), or Re being in case of general formula (lib) wherein X, R4 and R5a , Rsb, Rsc, Rsd having the above meaning with molecular oxygen 1502, 1602, 1702 or 1802, or a mixture thereof, wherein the reaction is carried out in water, an organic solvent or in a mixture thereof. 2. Method according to claim 1 , characterized in that the molecular oxygen 1502, 1602, 1702 or 1802 is added in a ratio of ratio 0.1 - 1000 equivalents, preferably 0.5 - 500 equivalents, more preferably 1 -100 equivalents in respect to the cyclodiene of general formula (II). 3. Method according to one of the preceding claims, characterized in that the reaction is carried out at a partial pressures below or above atmospheric pressure, preferably at atmospheric pressure. 4. Method according to one of the preceding claims, characterized in that Ri and R2 of general formula (I) are the same or different and are H, D, T or -Si (R3a, R3b, R3c)3, with R a,R b,R c being substituted or non-substituted C1 -C3 alkyl. 5. Method according to one of the preceding claims, characterized in that Ri and R2 of general formula (I) are the same or different and are H or -Si (R3a, R3b, R3c)3, with R a,R b,R c being methyl, ethyl, n-propyl, isopropyl. 6. Method according to one of the preceding claims, characterized in that R5a , Rsb, Rsc, R5d being H, D, substituted or non-substituted C1 -C3 alkyl, in particular methyl, ethyl, n-propyl, isopropyl, and the same or different. 7. Method according to one of the preceding claims, characterized by a cyclodiene of one of the following structures (V)-(VII): wherein R4, Re, Rsa , Rsb, Rsc, Rsd, and R7a-h have the above meaning. 8. Method according to one of the preceding claims, characterized by a cyclodiene of one of the following structures (VI ll)-(XI) : wherein R4, Re, Rsa , Rsb, Rsc, Rsd, and R7a-h have the above meaning. 9. Method according to one of the preceding claims, characterized in that R4 and R6 are - Si (R3a, R3b, R3C)3, with R3a.R3b.R3c being C1 -C3 alkyl, in particular methyl, ethyl, n- propyl, isopropyl. 10. Method according to one the preceding claims, characterized in that the cyclodiene of general formulae (lla) is 1 1 . Method according to one of the preceding claims, characterized in that the cyclodiene of general formulae (lib) is 12. Method according to one of the preceding claims, characterized in that the organic solvent is selected from a group comprising dichloromethane, t-butanol, ethanol, methanol, toluene, methyl-t-butyl-ether, acetonitrile, tetrahydrofuran, N-methyl-2- pyrrolidone. |
The present invention refers to a method for obtaining peroxides by oxygen activation using organosilicon agents.
Description
Oxygenation is one of the most fundamental chemical transformations, with direct applications in industrial processes. Ideally, molecular oxygen is the most atom-economical and environmentally friendly primary oxidant. It is however rarely used as a primary oxidant in low temperature homogeneous processes. This is a consequence of the kinetic inertness of 0 2 , due to its triplet ground state. In fact, in nature, 0 2 activation is accomplished by (mono- or di- ) oxygenases, where riboflavin-based coenzymes activate 0 2 under mild conditions to form a hydroperoxide intermediate, which is then used to transfer the oxygen atom to the substrates, in reactions such as phenol hydroxylation, Baeyer-Villiger oxidation, olefin epoxidation, hypochlorous formation etc. Similarly, in industrial processes, 0 2 is reacted with hydrocarbon to generate alkyl hydroperoxide or transformed into H 2 0 2 via the anthraquinone process.
Because isotopically labeled hydrogen peroxide, H 2 0 2 (H = 1 H, 2 H, 3 H; O = 15 0, 16 0, 17 0 , 18 0, except for 1 H 2 16 0 2 and 1 H 2 18 0 2 ) is commercially not available, they are in general synthesized in each laboratory when necessary. In common organic, inorganic, and bio engineering laboratories, the ways to produce isotopically labeled H 2 0 2 are, however, rather limited.
The typical method is the above mentioned anthraquinone method. Here 2-ethyl anthraquinone is hydrogenated in 1 -decanol at 2 atm by a Pd/C catalyst to give the corresponding anthradihydroquinone, which reacts with 0 2 gas to give H 2 0 2 in the solvent medium. H 2 0 2 is extracted with deionized water from the solvent medium, followed by distillation and concentration if necessary, giving aqueous H 2 0 2 in ca. 80% yield (to 0 2 gas used). Since 15 0 2 , 17 0 2 and 18 0 2 are quite expensive, the conversion efficiency of 0 2 gas is the most important factor.
The above-mentioned method is not convenient because of the following reasons: 1 ) Hydrogen apparatus for high pressure reaction is needed. 2) Trace organic impurities derived from 2- ethyl anthraquinone can contaminate aqueous H 2 0 2 . 3) Plenty of 1 -decanol is used as the solvent to dissolve 2-ethyl anthraquinone, hence plenty of deionized water needs to be used during the extraction from the reaction medium. As a result, the concentration of the obtained aqueous H 2 0 2 is low, which is not appropriate for some organic transformations, and 4), if needed, distillation and concentration of the aqueous H 2 0 2 is required. However, there is a risk that H 2 0 2 decomposes during the process because H 2 0 2 is thermally sensitive.
Silylated peroxides, such as Bis(trialkylsilyl)peroxide, (R 3 Si) 2 0 2 , are commonly prepared by reaction of H 2 0 2 -urea with R 3 SiCI. Accordingly, to obtain isotopically labeled (R 3 Si) 2 0 2 (O = 17 0 , 18 0), preparation of the corresponding isotopically labeled H 2 0 2 (O = 17 0 , 18 0) and isolation as H 2 0 2 -urea are required in advance.
As easily can be seen the presently applied methods for obtaining peroxides using molecular oxygen are cumbersome and tedious and require high pressure equipment.
It was therefore an object of the present invention to provide a method for obtaining peroxides, which can be conducted in a simple manner and at atmospheric pressure.
This object is solved by a method with the features of claim 1 .
Accordingly, a method for obtaining peroxides of the general formula (I)
Ri - O - O - R 2 (I)
wherein
R I , R 2 can be the same or different,
Ri, R 2 being H, D ( 2 H), T( 3 H), -Si (R 3a , R 3b , R 3c ) 3 , with R 3a R 3b R 3c being H, substituted or unsubstituted linear or branched C1 -C5 alkyl, R 3a, R 3b, R 3c being the same or different, and
O is 15 0, 16 0, 17 0 or 18 0, or a mixture thereof,
is provided,
wherein a cyclodiene compound of the general formula (II)
wherein
X being CH, CD, CT or N,
R 4 being -Si (R 3a , R 3b , R 3c ) 3 , with R 3a , R 3b , R 3c having the above meaning,
Rs a , R 5b , R5 C, Re d being H, D, T, substituted or unsubstituted linear or branched C1 -C5 alkyl, R 5a , Rsb, Rsc, Rsd being the same or different; or
wherein R 5a , R 5b and R 5c , Rs d can be part of a C6 aryl ring according to one of the following structures (III) or (IV):
R 7a-h being H, substituted or unsubstituted linear or branched C1 -C5 alkyl, and R 7a-h being the same or different.
R 6 being -Si (R 3a , R 3b , R 3c ) 3 , with R 3a , R 3b , R 3c having the above meaning in case of general formulae (lla), or
Re being
in case of general formula (lib) wherein X, R 4 and R 5a , Rsb, Rsc, Rsd having the above meaning is reacted with molecular oxygen 15 0 2 , 16 0 2 , 17 0 2 or 18 0 2 , or a mixture thereof, wherein the reaction is carried out in water, an organic solvent or in a mixture thereof.
Thus, a method for the synthesis of peroxides is provided that does not require the use of a complex hydrogenation apparatus. Any by-products formed can be easily removed from the reaction mixture, for example by washing with pentane, giving analytically pure aqueous peroxide, such as H2O2. The use of organic solvent can be minimized or even avoided. High concentration of peroxide, for example in case of H 2 0 2 to about 15 wt%, can be obtained with still further possibility for concentration. In case of silylated peroxides such as (R 3 Si) 2 0 2 the reaction steps for the production of (R 3 Si) 2 0 2 from 0 2 are reduced because the additional process via H 2 0 2 is not needed.
In an embodiment of the present method the molecular oxygen 15 0 2 , 16 0 2, 17 0 2 or 18 0 2 is added to the reaction mixture in a ratio of ratio 0.1 - 1000 equivalents, preferably 0.5 - 500 equivalents, more preferably 1 -100 equivalents in respect to the cyclodiene of general formula (lla,b). In some embodiments the molecular oxygen is added in a ratio of 0.8 - 50 equivalents, preferably 0.8 - 10 equivalents, more preferably 0.8 -1 .5 equivalents, most preferably 1 -1 .3 equivalents in respect to the cyclodiene of general formula (lla,b). It is to be understood that 0 2 can be used as part of a gasous mixture like Synhetic Air, 0 2 /Ar and 0 2 /N 2 , 0 2 /Ar mixture.
It is also possible to add molecular oxygen according to the formulae nO-mO with n different from m and n, m = 15, 16, 17 and 18.
In a further embodiment of the present method the reaction is carried out at a partial pressure below or above atmospheric pressure, preferably at atmospheric pressure. This has the advantage that complex lab systems can be avoided.
In an embodiment of the method the moieties R1 and R2 of general formula (I) are the same or different and are substituted or unsubstituted C6-C12 aryl wherein in each case one or multiple carbon atoms can be substituted by one or multiple oxygen atoms, sulphur atoms, substituted nitrogen atoms, selenium atom, boron atom, double bonds and/or by one or multiple groups of the type -C(0)0-, -C(O)-, -C(0)-H, -NHC(0)0-, -OC(0)NH- and/or -0C(0)0-; and/or can be functionalized by one or multiple hydroxyl groups, halogens, amino groups, seleno groups and/or mercapto groups.
In one embodiment of the method the moieties R1 and R2 of general formula (I) are the same or different and are H, D ( 2 H), T ( 3 H), -Si (R 3a , R 3b , R 3c ) 3 , with R 3a, R 3b , R 3c being H, substituted or unsubstituted linear or branched C1 -C5 alkyl, or substituted or unsubstituted C6-C12 aryl wherein in each case one or multiple carbon atoms can be substituted by one or multiple oxygen atoms, sulphur atoms, substituted nitrogen atoms, double bonds and/or by one or multiple groups of the type -C(0)0-, -C(O)-, -NHC(0)0-, -0C(0)NH- and/or -0C(0)0- In yet another embodiment of the method the moieties Ri and R 2 of general formula (I) are the same or different and are H, D or -Si (R 3a , R 3b , R 3c ) 3 , with R 3a .R 3b .R 3c being substituted or non- substituted C1 -C3 alkyl. Specifically, the moieties R 1 and R 2 of general formula (I) are the same or different and are H or -Si (R 3a , R3b, R3c)3, with R3a.R3b.R3c being methyl, ethyl, n-propyl, isopropyl. For example, the peroxides obtained by the present method may be H 2 0 2, (Me 3 Si) 2 0 2 or (Et 3 Si) 2 0 2 .
In a further embodiment of the present method the moieties R 5a , Rs b , Rs c, Rs d are substituted or unsubstituted C1 -C10 alkoxy or substituted or unsubstituted C6-C12 aryl wherein in each case one or multiple carbon atoms can be substituted by one or multiple oxygen atoms, sulphur atoms, substituted nitrogen atoms, double bonds and/or by one or multiple groups of the type -0(0)0-, -C(0)-, -C(0)-H, -NHC(0)0-, -0C(0)NH- and/or -0C(0)0-; and/or can be functionalized by one or multiple hydroxyl groups, amino groups and/or mercapto groups, wherein R 5a , Rsb and R 5c , Rsd can be part of a cyclic structure respectively
In a variant of the present method the moieties R 5a , Rs b , Rs c, Rs d are H, D, T, substituted or unsubstituted linear or branched C1 -C5 alkyl or substituted or unsubstituted C1 -C10 alkoxy or substituted or unsubstituted C6-C12 aryl wherein in each case one or multiple carbon atoms can be substituted by one or multiple oxygen atoms, sulphur atoms, substituted nitrogen atoms, double bonds and/or by one or multiple groups of the type -0(0)0-, -C(0)-, - NHC(0)0-, -0C(0)NH- and/or -0C(0)0-;wherein R 5a , Rs b and R 5c , Rs d can be part of a cyclic structure respectively; R 5a , Rsb, Rsc, Rsd being the same or different.
In still another variant of the present method the moieties R 5a , Rs b , Rs c, Rs d are H, Dsubstituted or non-substituted C1 -C3 alkyl, in particular methyl, ethyl, n-propyl, isopropyl or , substituted or unsubstituted C1 -C5, alkoxy, preferably methoxy and ethoxy.
As mentioned above the moieties R 5a , Rs b and R 5c , Rs d are part of C6 aryl ring according to one of the following structures (III) or (IV):
wherein
R 4J Re, Rsa, R 5b and X have the above meaning, and
R 7a-h being H, D, T, substituted or unsubstituted linear or branched C1 -C5 alkyl, and R 7a-h being the same or different.
In a variant the moieties R 7a-h may be , substituted or unsubstituted C1 -C10 alkoxy or substituted or unsubstituted C6-C12 aryl wherein in each case one or multiple carbon atoms can be substituted by one or multiple oxygen atoms, sulphur atoms, substituted nitrogen atoms, double bonds and/or by one or multiple groups of the type -0(0)0-, -C(0)-, -C(0)- H, -NHC(0)0-, -0C(0)NH- and/or -0C(0)0-; and/or can be functionalized by one or multiple hydroxyl groups, amino groups and/or mercapto groups, and R 7a-h being the same or different.
In a further variant the moieties R 7a-h are H, D, T substituted or unsubstituted linear or branched C1 -C5 alkyl, substituted or unsubstituted C1 -C10 alkoxy or substituted or unsubstituted C6- C10 aryl wherein in each case one or multiple carbon atoms can be substituted by one or multiple oxygen atoms, sulphur atoms, substituted nitrogen atoms, double bonds and/or by one or multiple groups of the type -0(0)0-, -C(0)-, -NHC(0)0-, -0C(0)NH- and/or - 00(0)0-, and R 7a-h being the same or different.
In still another variant of the present method the moieties R 7a-h are H, substituted or non- substituted C1 -C3 alkyl, in particular methyl, ethyl, n-propyl, isopropyl or , substituted or unsubstituted C1 -C5, alkoxy, preferably methoxy and ethoxy.
In more specific embodiments the cyclodiene may be of one of the following structures (V)- (VII):
wherein R 4 , R 6, Rsa , Rsb, Rsc, Rsd, and R 7a -h have the above meaning.
It is particularly preferred that a trimethylsilyl group is used for both of R and R 6 positions and methyl or methoxy groups are used at R 5a position (R b-d = H) for the above structures V-VII, in particular in case of structure V. In further more specific embodiments the cyclodiene may be of one of the following structures (VI I l)-(XI) :
wherein R 4 , R 6, Rsa , Rsb, Rsc, Rsd, and R 7a -h have the above meaning. In some embodiments a trimethylsilyl group for both of R 4 and R 6 positions and a methyl group on R 5a/5d (R5b,5c = H) or on R 5a -d for the structure VIII, a trimethylsilyl group for both of R 4 and R 6 positions and an ethyl group on R 5a/5b (R ?a-d = H) for the structure IX, a trimethylsilyl group for both of R 4 and R 6 positions and hydrogen on R 7a-h for the structure X, a trimethylsilyl group for both of R 4 and R 6 positions and hydrogen on R 5a-d for the structure XI are preferred.
The term“substituted” in connection to alkyl and aryl relates to the substitution of one or more atoms, usually H-atoms, by one or more of the following substituents: halogen, hydroxy, protected hydroxy, oxo, protected oxo, C 3 -C7-cycloalkyl, phenyl, naphthyl, amino, protected amino, primary, secondary or tertiary amino, heterocyclic ring, imidazolyl, indolyl, pyrrolidinyl, CrCi2-alkoxy, CrCi 2 -acyl, CrCi 2 -acyloxy, nitro, carboxy, carbamoyl, carboxamid, N-(CrCi 2 - alkyl)carboxamid, N,N-Di(Ci-Ci 2 -alkyl)carboxamid, cyano, methylsulfonylamino, thiol, C1-C10- alkylthio und Ci-Ci 0 -alkylsulfonyl. The substituted groups can be once or twice substituted with same or different substituents.
Examples for the above substituted alkyl groups comprise 2-oxo-prop-1 -yl, 3-oxo-but-1 -yl, cyanomethyl, nitromethyl, chlormethyl, hydroxymethyl, tetrahydropyranyloxymethy, trityloxymethyl, propionyloxymethyl, aminomethyl, carboxymethyl, allyloxycarbonylmethyl, allyloxycarbonylaminomethyl, methoxymethyl, ethoxymethyl, t-butoxymethyl, acetoxymethyl, chlormethyl, brommethyl, iodmethyl, trifluormethyl, 6-hydroxyhexyl, 2,4-dichlor(n-butyl), 2- aminopropyl, 1 -chloroethyl, 2-chloroethyl, 1 -bromoethyl, 2-bromoethyl, 1 -fluoroethyl, 2- fluoroethyl, 1 -iodoethyl, 2-iodoethyl, 1 -chloropropyl, 2-chloropropyl, 3-chloropropyl, 1 - bromopropyl, 2-bromopropyl, 3-bromopropyl, 1 -fluoropropyl, 2-fluoropropyl, 3-fluoropropyl, 1 - iodopropyl, 2-iodopropyl, 3-iodopropyl, 2-aminoethyl, 1 -aminoethyl, N-benzoyl-2-aminoethyl, N-acetyl-2-aminoethyl, N-benzoyl-1 -aminoethyl, N-acetyl-1 -aminoethyl and alike.
The term “Ci-Ci 2 -alkyl” relates to moieties like methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, s-butyl, t-butyl, amyl, t-amyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, and alike. Preferred Ci-Ci 2 -alkyl groups are methyl, ethyl, isobutyl, s-butyl und isopropyl.
The term“oxo” relates to a carbon atom, which is connected with an oxygen atom via a double bond whereby a keto or an aldehyde group is formed. The term“protected oxo” relates to a carbon atom, which is substituted by two alkoxy groups or is connected twice with a substituted diol forming a non-cyclic or cyclic ketal group.
The term“alkoxy” relates to moities like methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, t- butoxy and alike. A preferred alkoxy group is methoxy. It a further variant of the present method the moieties R 4 and R 6 are -Si (R 3a , R3b, R3c)3, with R3 a, R3 b, R3 c being C1 -C3 alkyl, in particular methyl, ethyl, n-propyl, isopropyl.
In a very specific embodiment of the present method the cyclodiene of general formulae (I la) is
The cyclodiene of general formula (lib) may also be one of
The reaction of the present method is carried out in water, in an organic solvent or in a mixture thereof. The organic solvent may be selected from a group comprising dichloromethane, t- butanol, ethanol, methanol, toluene, methyl-t-butyl-ether, acetonitrile, tetrahydrofuran, N- methyl-2-pyrrolidone. However, any other suitable organic solvent may be used.
The invention is described in the following in more detail by means of several examples.
Example 1 :
At ambient temperature and atmospheric pressure, a reaction of 0 2 (1 equiv.) with 1 -methyl- 3, 6-bis(trimethylsilyl)-1 ,4-cyclohexadiene in CH2CI2/H2O for 16 hours produces H 2 0 2 in 81 % yield in the water phase. The aqueous H 2 0 2 phase can be separated or directly used for further oxidation as a one-pot reaction. Example 2:
At ambient temperature and atmospheric pressure, a reaction of 0 2 (1 equiv.) with 1 -methyl- 3,6-bis(trimethylsilyl)-1 ,4-cyclohexadiene in H 2 0 for 16 hours produces H 2 0 2 in 78% yield in the water phase. The aqueous H 2 0 2 phase can be separated or directly used for further oxidation in a one-pot reaction.
Example 3:
At ambient temperature and atmospheric pressure, a reaction of 0 2 (1 equiv.) with 1 -methyl- 3, 6-bis(trimethylsilyl)-1 ,4-cyclohexadiene in t-butanol for 16 hours gives H 2 0 2 in 93% yield in the solvent medium. The obtained H 2 0 2 in t-butanol can be directly used for further oxidation in a one-pot reaction.
Table 1 summarizes the H 2 0 2 yields using different solvent systems.
0 2 (1 atm, 1 equiv.)
H 2 0 2
Solvent, rt, 16 h
- bis-trimethylsilytoluene
1 (cis:trans = 1 : 6)
Entry Solvent Yield(%) of H 2 0 2
1 CH 2 CI 2 (9 mL) / H 2 0 (1 mL) 81
2 CH 2 CI 2 (9 mL) / H 2 0 (0.4 mL) 80
3 CH 2 CI 2 (9 mL) / H 2 0 (0.1 mL) 74
4 CH 2 CI 2 (9 mL) 40
5 toluene (9 mL) / H 2 0 (1 mL) 79
6 MTBE (9 mL) / H 2 0 (1 mL) 75
7 H 2 0 (10 mL) 78
8 t-butanol (9 mL) 93
9 CH 3 CN (9 mL) 98
10 NMP (9 mL) 97 11 THF (9 mL) 88
12 a CH 2 CI 2 (9 mL) / H 2 0 (1 mL) 46 b a The reaction is carried out under synthetic air (1 atm, constant). fc The
conversion of 1 is 50%.
Table 1 : H 2 0 2 formation by the reaction of 1 with 0 2 Example 4:
At atmospheric pressure, 0 2 (1 .3 equiv.) is added to a solution of N,N'- bis(trimethylsilyl)-4,4'- dihydrobipyridine in CH 2 CI 2 at -78 e C. The solution was warmed to ambient temperature, followed by trap-to-trap distillation to give (Me 3 Si) 2 0 2 in a 99% yield in CH 2 CI 2 . Example 5:
At atmospheric pressure, 0 2 (1 .3 equiv.) is added to a solution of bis(trimethylsilyl)-2, 3,5,6- tetramethyldihydropyrazine in CH2CI2 at -78 e C. The solution was warmed to ambient temperature, followed by trap-to-trap distillation to give (Me 3 Si) 2 0 2 in a 99% yield in CH2CI2.
Example 6:
At ambient temperature, synthetic air (1 atm (20%0 2 /80%N 2 ), flow) is added to a solution of 1 - methyl-3, 6-bis(trimethylsilyl)-1 ,4-cyclohexadiene in CH2CI2/H2O for 16 hours produces H2O2 in
46% yield in the water phase. The aqueous H 2 0 2 phase can be separated or directly used for further oxidation as a one-pot reaction.
Table 2 summarizes the (Me 3 Si) 2 0 2 yields using different solvent systems.
SiMe 3
2
Entry Reductant Solvent Yield (%) of (Me 3 Si) 2 0 2
1 2 CH 2 CI 2 99
2 2 C0H0 99
3 2 Et 2 0 99
4 2 THF 99
5 2 pentane 99
6 3 CH 2 CI 2 93
Table 2: Bistrimethylsilylperoxide (BTSP) formation by the reaction of 2 and 3 with 0 2 .
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