Initiator for preparing alkanesulfonic acids from alkane and oleum

Abstract

A compound of the formula:
CH.sub.3SO.sub.2OOSO.sub.2OH.

Claims

1. A compound of the formula
CH.sub.3SO.sub.2OOSO.sub.2OH.

2. A mixture comprising the compound of claim 1 and sulfuric acid, alkylsulfonic acid, methanesulfonic acid, or combinations thereof.

3. A process for manufacturing the compound according to claim 1 comprising: reacting an alkanesulfonic acid with a hydrogen peroxide; then adding oleum; followed by the isolation of the compound.

4. The process according to claim 3, wherein said separating is effected by precipitation or chromatography.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows schematically, in an exemplary way, a simple system according to the invention for the manufacturing of methanesulfonic acid according to the invention.

(2) FIG. 2 shows a schematic layout of a preferred device.

DETAILED DESCRIPTION

(3) The process according to the invention allows for alkane sulfonation, especially methane sulfonation, in a reactor system using oleum with alkane, especially methane, with addition of the compound according to the invention as an initiator. Advantageously, the raw product can be purified by distillation, which already yields a relatively pure alkanesulfonic acid, especially methanesulfonic acid, as a distillate.

(4) The residue consists of sulfuric acid with a content of up to 10% alkanesulfonic acid, especially methanesulfonic acid (MSA). These distillation bottoms may be used 1) as a solvent for the continuous reaction in the reactor; 2) for the preparation of fresh oleum with pure sulfur trioxide; 3) by reacting hydrogen peroxide (30% to 100% (w/w) solution in water), the compound according to the invention can be prepared, which may be employed as an initiator or precursor for it.
ALK-SO.sub.2OH+H.sub.2O.sub.2.fwdarw.ALK-SO.sub.2OOH+H.sub.2O.Reaction scheme 1:

(5) The compound according to the invention is capable of reacting with oleum to form a mixed acid peroxide. This yields the initiator, the compound according to the invention.
ALK-SO.sub.2OOH+SO.sub.3.fwdarw.ALK-SO.sub.2OOSO.sub.2OHReaction scheme 2:

(6) This mixed peroxo anhydride is characterized by a high reactivity as compared to DMSP (dimethylsulfonyl peroxide, H.sub.3CSO.sub.2OOSO.sub.2CH.sub.3), which is known from the prior art, for example, and which causes longer reaction times. At the same time, however, the selectivity of the DMSP in view of the formation of side products is obtained. In contrast, peroxodisulfuric acid (Marshall's acid) is very reactive and very little selective. The compound according to the invention combines the selectivity of DMSP with the reactivity of Marshall's acid.

(7) In the following, the invention is further illustrated in an exemplary way taking the preparation of methanesulfonic acid as an example.

Example 1

(8) Preparation of the Initiator Solution

(9) To a mixture consisting of 90 ml of 100% sulfuric acid and 10 ml of methanesulfonic acid, 3.4 ml of 70% (w/w) hydrogen peroxide is added dropwise with external cooling and intensive stirring.

(10) Synthesis Protocol:

(11) In a 3.75 L autoclave, 1000 g of 36% (w/w) oleum is charged, and the temperature controlled to 50 C. After a pressure of 100 bar of methane gas was set, intensive stirring is performed with a stirrer from the company Parr. Now, the initiator solution is metered dropwise to the solution. The pressure drops to 35 bar within 5 hours. The yield is higher than 90%, based on sulfur trioxide. The reaction product contains 42% (w/w) methanesulfonic acid.

Example 2

(12) Preparation of the Initiator Solution

(13) To a mixture consisting of 90 ml of 100% sulfuric acid and 10 ml of methanesulfonic acid, 3.4 ml of 70% (w/w) hydrogen peroxide is added dropwise with external cooling and intensive stirring.

(14) Synthesis Protocol:

(15) In a 3.75 L autoclave, 1000 g of 36% (w/w) oleum is charged, and the temperature controlled to 35 C. After a pressure of 100 bar of methane gas was set, intensive stirring is performed with a stirrer from the company Parr. Now, the initiator solution is metered dropwise to the solution. The pressure drops to 35 bar within 5 days. The yield is higher than 90%, based on sulfur trioxide. The reaction product contains 42% methanesulfonic acid.

(16) Characterization of Monomethylsulfonyl Peroxide:

(17) Using different analytical techniques monomethylsulfonyl peroxide was characterized. Using mass spectroscopy the molecular weight was determined as M=191.94 g/mol. The .sup.1H-NMR (D.sub.2SO.sub.4) shows a signal for the Methylgroup at 3.43 ppm. A suitable way in order to measure the peroxide content is titration (Jander, Jahr, Maanalyse, Theorie und Praxis der Titrationen mit chemischen und physikalischen Indikationen, 17. Auflage, Walter de Gruyter GmbH 2009, Berlin).