Preparation of di-t-alkyl peroxides and t-alkyl...

Details Preparation of di-t-alkyl peroxides and t-alkyl... Preparation of di-t-alkyl peroxides and t-alkyl...

1999-12-10

2001-05-01

Vollano, Jean F. (Department: 1621)

Organic compounds -- part of the class 532-570 series

Organic compounds

Oxygen containing

C568S568000

Reexamination Certificate

active

06225510

ABSTRACT:

FIELD OF THE INVENTION
The present invention is directed to a new synthetic route for making di-t-alkyl peroxides such as di-t-butyl peroxide (DTBP) and t-alkyl hydroperoxides such as t-butyl hydroperoxide (TBHP). In the inventive process an n-alkyl t-alkyl ether, such as methyl t-butyl ether (MTBE), and hydrogen peroxide are used in an acid catalyzed reaction.
BACKGROUND OF THE INVENTION
DTBP is used as initiator in polyethylene production and as a crosslinking agent in wire/cable manufacturing. In U.S. Pat. No. 5,314,511, U.S. Pat. No. 4,406,254 and Coughenour, et al, CHEMTECH 1997 (August) 38-41, DTBP is reported as an effective fuel enhancement additive.
DTBP is most commonly made by reacting TBHP with t-butyl alcohol (TBA) in an aqueous solution using an acid catalyst such as mineral acids (e.g. sulfuric acid, hydrochloric acid), phosphonic acids, p-toluene sulfonic acid, strong acid ion exchange resins (e.g. Amberlyst® 15), heteropolyacids and Lewis acids. References describing such processes include U.S. Pat. No. 4,810,809, U.S. 5,488,176; U.S. 5,288,919; U.S. 5,488,179; U.S. 5,488,178; U.S. 5,345,009; Milas, N. A., et al,
J. Amer. Chem. Soc.,
1946, 68 (2) 205-208; and Dickey, F. H., et al,
Ind. Eng Chem.
1949, 41(8) 1673-1679. DTBP is also made commercially by reacting TBA with hydrogen peroxide in the presence of sulfuric acid as a catalyst in a manner as described in Gupta, A. A., et al, “An Improved Process for the Preparation of Di-Tertiary-Butyl Peroxides,” IN 173171 (1990). Isobutylene can be used as feed stock instead of TBA as described in U.S. Pat. No. 5,371,298.
An oxidation of isobutane followed by reacting the oxidate in an aqueous solution of an acid catalyst is another known method for the preparation of DTBP, as described in Dickey, et al,
Ind. Eng. Chem.
1949, 41(8) 1673-1679, in EP 438844 A and in U.S. Pat. No. 5,312,998.
Yet another method for DTBP production includes a reaction of an alkali or alkaline-earth metal salt of TBHP with a t-butyl halide, as described in Dickey, et al,
Ind. Eng Chem.
1949, 41(8) 1673-1679 and in Baj, S.,
J. Mol. Catalysis,
1996, 106, 11-23.
TBHP is widely used in latex formulation and as an intermediate in manufacturing peroxyesters, peroxyketals and DTBP. Known methods of TBHP synthesis are similar to methods for DTBP synthesis. Documents describing such synthesis include Milas, N. A., et al,
J. Amer. Chem. Soc.,
1946, 68(2) 205-208; U.S. Pat. No. 5,399,777; EP 639564; U.S. Pat. No. 5,243,084; JP 3/190856 A (1991); Michert, E.,
Chem. Stosow.,
1988 32(1) 171-178; and Milas, N. A., et al,
J. Amer. Chem. Soc.,
1938, 60 (10) 2434-2436.
Davies, et al,.
J Chem. Soc.
1958, 4637-4643 describes preparation of certain optically active secondary alkylphenyl hydroperoxides from corresponding alcohols or ethers and hydrogen peroxide.
U.S. Pat. No. 5,866,712 describes use of MTBE as an inert solvent in a process for synthesis of oxalate perester compounds.
SUMMARY OF THE INVENTION
The invention is a process for production of a t-alkyl hydroperoxide or di-t-alkyl peroxide compound comprising the steps of
a) reacting an n-alkyl t-alkyl ether with a reactant mixture comprising an acid catalyst and a compound of the formula
RO
2
H  (I)
 where R is H or t-alkyl, provided that if R is t-alkyl the t-alkyl peroxide compound product is a di-t-alkyl peroxide,
b) isolating a reaction product comprising said t-alkyl peroxide compound from the mixture resulting from step a).
The reaction of step a) is preferably performed as a single step reaction. Alternatively, however, it may be broken into two steps, a hydrolysis reaction of the ether in the presence of the acid catalyst, followed by in situ addition of, and reaction with, RO
2
H.
Product yields are affected by reactant ratios and other process parameters. Preferred process parameters comprise further aspects of the invention.
DETAILED DESCRIPTION OF THE INVENTION
The entire disclosures of all US patents and other published documents and any copending US patent applications mentioned anywhere herein are expressly incorporated herein by reference.
It has been discovered that t-alkyl peroxides, such as DTBP and TBHP can be readily produced in high yield from corresponding n-alkyl t-alkyl ethers such as MTBE. The inventive process is especially advantageous for the production of DTBP.
The process can also be applied to preparation of other di-t-alkyl peroxides and t-alkyl hydroperoxides.
n-Alkyl t-alkyl ethers can be cleaved or hydrolyzed into the mixture of corresponding alcohols (aqueous solutions) or alkanol and t-olefins (non-aqueous solutions) in the presence of an acidic catalyst. Known catalysts for such reactions include inorganic and organic acids, acidic ion-exchange resins, Lewis acids, heteropolyacids, etc. Some olefins are produced according to this methodology and previous work attempting to synthesize a t-amyl alcohol from t-amyl methyl ether did not go to completion due to a product/reactant equilibrium which when shifted by distilling out methanol resulted in the dehydration of the t-amyl alcohol product to isoamylene.
The present invention avoids the problems encountered in isolating the t-alkyl alcohol product of acid catalyzed hydrolysis of t-alkyl ethers This is accomplished by performing the hydrolysis/peroxidization reactions in situ, that is without isolation of an alcohol intermediate.
While the following description is made primarily with reference to preparation of DTBP and TBHP from MTBE, it should be understood that the process described and illustrated is applicable to preparation of these or other di-t-alkyl peroxides and t-alkyl hydroperoxides by substituting corresponding n-alkyl t-alkyl ethers for MTBE. With respect to the ethers which may be used in the inventive process, the n-alkyl portion thereof suitably may have 1-4 carbon atoms, preferably 1-2 carbon atoms, and the t-alkyl portion thereof suitably may have from 4 to about 10 carbon atoms, preferably 4-6 carbon atoms. Examples of suitable n-alkyl t-alkyl ethers include MTBE, methyl t-amyl ether, methyl t-hexyl ether, ethyl t-butyl ether, ethyl t-amyl ether, ethyl t-hexyl ether, n-propyl t-butyl ether, n-propyl t-amyl ether, and n-propyl t-hexyl ether.
In formula (I), above, R may be H for syntheses of either a t-alkyl hydroperoxide or di-t-alkyl peroxide, such that the compound RO
2
H is hydrogen peroxide. For the preparation of di-t-alkyl peroxide, however, R may alternatively be t-alkyl (suitably having from 4 to 10 carbon atoms), such that the compound R
0
2
H is a t-alkyl hydroperoxide. Hydrogen peroxide is generally suitable for synthesis of both t-alkyl hydroperoxides and symmetric di-t-alkyl peroxides compounds. A process of the invention using t-alkyl n-alkyl ether and t-alkyl hydroperoxide reactants in which the respective reactants have different t-alkyl groups effects the preparation of asymmetric di-t-alkyl peroxides.
Generally, the ratio of the RO
2
H compound of formula (I) to the ether reactant may be from about 0.3 to about 5, on a mole basis. The product yield, as between DTBP and TBHP using hydrogen peroxide as the compound RO
2
H, is determined primarily by stoichiometric ratio of ether to hydrogen peroxide. In general, DTBP is the predominant product at H
2
O
2
/MTBE mole ratios below about 0.7. TBHP is predominant at H
2
O
2
/MTBE mole ratios above 1. Preferred H
2
O
2
/MTBE ratios for preparation of DTBP are in the range of from 0.4-0.6. For TBHP, the H
2
O
2
/MTBE ratio is preferably in the range of 1.5-3.
An acid is used as catalyst in the reaction. Acid catalysts may be inorganic acids, organic acids, acidic ion-exchange resins (for instance Amberlyst® 15 ion exchange resin), Lewis acids, heteropolyacids (for instance phosphotungstic), etc. Suitably the acid is a mineral acid such as sulfuric, hydrochloric or nitric acid. Sulfonic acids such as methane sulfonic and p-toluene sulfonic acids are further examples of acids which may be used as the catalyst. Sulfuric acid is particularly suitable. Preferred H
2
SO
4
/MTBE mole ratios are in the range of

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