DE2225733C2 - Process for the continuous production of alkanesulfonic acids - Google Patents

Description

in a medium containing aqueous hydrogen chloride solution in a turbulent reaction zone at 85 ° to about 115 ° C., a feed rate of at least about 1.3 kg / h with an upper limit of about 7.1 kg / h of alkyl mercaptan or dialkyl disulfide, each 28.3 dm ^{3 of} the reaction / .onc, complies

2. The method according to claim 1, characterized in that the reaction at about 95 ° to 100 "C performs

It is known (Houben-Weyl; "Methods of Organic Chemistry", 4th edition, Vol. 9, 1955, pp. 368, 369 and 372), low molecular weight alkyl mercaptans and dialkyl sulfides by oxidation to corresponding sulfonic acids Driving over. The oxidizing agents are nitric acid, permangarate and dichromate, hydrogen peroxide, bromine and iodine in aqueous solution and hypobromite have been proposed. For example, cetylsulfonic acid is used in 36% yield from cetyl mercaptan by oxidation with potassium permanganate by heating for 5 hours Manufactured in a water bath by catalytic oxidation of primary and secondary aliphatic mercaptans or DisulHde, low molecular weight aliphatic sulfonic acids have been obtained in good yields. disadvantage the previous process was the relatively low yield of sulfonic acids or the need to use catalysts, which incurs additional costs, the process product separated and separated the catalyst may have to be regenerated.

In US-PS 31 30 221, the 1,1-Dihydroperfluoräthylsulfonsäure is described which is formed in aqueous suspension at 30-80 ⁰ C from the corresponding disulfide by reaction with chlorine temperatures above 80 ° C are to be avoided.

The invention is based on the object of a process for the preparation of alkanesulfonic acids with 1-4 To indicate carbon atoms in the alkyl group, which is carried out without the use of a catalyst and still leads to high yields of alkyl sulfonic acid at high speeds

The method specified in claim 1 is proposed to solve this problem. A preferred one The embodiment of the method forms the subject matter of claim 2.

The mercaptan and disulfide reactants used in the process of the invention are determined by the Formula RSX, in which X represents a hydrogen atom or a radical of the formula SR ', where R and R' represent alkyl groups having 1 to 4 carbon atoms and can represent identical or different radicals, are shown. The preferred reactants are methyl mercaptan and dimethyl disulfide, although good yields and high quality products are also made with ethyl mercaptan, the propyl mercaptans, the butyl mer- captanen, diethyl disulfide, dipropyl disulfide and dibutyl disulfide can be obtained.

The reaction carried out by the method of the invention can be illustrated by the following equation if a mercaptan feed is used:

RSK + 3 Cl ₂ + 3 H ₂ O ^RS ° 3 ^{H + 6 HC1}

and if a disulfide feedstock is used:

"Oc Ii ς" ρ

RSSR + 5Cl ₂ + 6 H ₂ O 2 RSO ₃ H + HCl and

RSSR '+ 5Cl ₂ + 6H ₂ O ^RSQ 3 ^H + R'SO ₃ H + IOHCI

The reaction medium is passed from the turbulent reaction zone into a product recovery zone from which a concentrated aqueous alkanesulfonic acid solution is drawn off and the aqueous hydrogen chloride medium (and alkanesulfonic acid which has not been drawn off) are returned to the turbulent reaction zone.

The preparation of alkanesulfonic acid according to the invention results in many advantages. For example

high product yields on the order of 96 to 98% using stoichiometri general amounts of gaseous chlorine reactants or at most using one up to about

5%, preferably 2 to 3%, excess obtained. Another major benefit is that the The present method for producing intimate contact of the reactants is not a mechanical one

Stirring device required, resulting in savings in investment and maintenance costs a The feed speed of the mercaptan (or disulfide) in the reaction zone, in which it is mixed with chlorine and water reacts, leads to a violent evolution of gaseous HCl, creating turbulence and intimate contact the reactant in the reaction zone would result in another important advantage of the process the short response time, d. H. the residence time of non-volatile constituents in the Reaktkmssystem, which for Achieving such surprisingly high yields is required. More precisely, the mean reaction times in the process can range from seconds to about 15 minutes, with generally less than one minute is the preferred period,

The alkanesulfonic acid product (ASA) produced here has an unexpectedly high quality. It is very surprising that the elevated reaction temperatures do not cause any undesired chlorination of the carbon chain of the alkanesulfonic acid Contains 85% alkanesulphonic acid The product can be sold as it is, but if a purified product is desired, a water-clear aqueous solution (70-85% concentration) or practically anhydrous alkanesulphonic acid is obtained by a simple cleaning technique using steam stripping or the like Process Manufactured The equipment for performing a typical process consists of (1) a source of superheated steam, (2) a cooker or reheater fitted with a thermometer bore, side take-off arm, steam inlet tube, and a suitable heater jacket An Oldershaw section with 10 floors, feed plate section with top head accessories for complete distillate removal is applied to the reheater. 97 ° C) introduced just prior to entering the column feed plate section. As the ASA crude travels down the column, it collides with an upward moving stream of superheated dry water vapor (approx. 190-215 ° C). The overhead distillates are then returned to the reactor This operation results in a chloride-free bottoms product containing 70 to 85% aqueous ASA material. The reheater volume is maintained by continuously removing some of the residue product. To produce a 100% anhydrous ASA product, a slightly different cleaning technique is used and carried out at reduced pressure. Basically, the system consists of a preheater, a dehydration column and an overhead product column. A hot (100 to 115 ° C) raw ASA stream is fed to the bottom of a coiled preheater at a pressure of 30 mm Hg abs. The feed entering the main dehydrogenation column is now about 95 to 97% ASA. The _{upstream vapor stream containing H 2} O, HCl and small amounts of entrained ASA is passed to an overhead condenser and passed to the recirculation. The downflowing 95-97% ASA is further dehydrated in the main dehydration column by the high temperature ASA heating by the reheater The ASA Residues from this reheater are passed into another column operating at low pressure (5 to 15 mm Hg). From there, the anhydrous residues are distilled overhead through a short column and collected as a water-clear anhydrous product.

The method of the invention is explained in more detail with reference to the drawing, in which a A pictorial flow sheet depicting a particular embodiment of the invention is shown. That Reactor system comprises a cylindrical reactor 16 and a cylindrical overflow reservoir 17, which over the Overflow line 7 and a return line 8 is connected Jacket 2 for temperature control, and the settling reservoir has an internal heat exchanger 11 with pipe coils, the steam or cooling water to regulate the temperature of the system within the desired limits can be supplied. One or both heat exchangers can be used by heat exchangers which are located in one or both lines 7 and 8 are replaced. The system is using aqueous Hydrochloric acid solution (20 to 37% by weight HCl, preferably about 20% HCl) is filled and it is gaseous chlorine metered from the feed tank 5 through line 6 and into the aqueous medium at the bottom of the Reactor 16 sprayed. At the same time, alkyl mercaptan or dialkyl disulfide or mixtures are used thereof from feed tank 3 through line 4 into reactor 16 at a point slightly above Fresh water or aqueous hydrochloric acid solution is metered in at the chlorine feed point or introduced intermittently into the reactor 16 via line 12 in order to supply the necessary water of reaction and maintain the correct level of fluid in the system.

The intensity and severity of the reaction cause considerable turbulence in the reaction zone 1, which means that the liquid level therein is increased considerably above the level of the overflow line 7. Gaseous HCl, unreacted chlorine and water vapor that occur as by-products come into contact with the cooled reflux condenser 12, whereby the majority of the entrained moisture is condensed and falls down into the reaction zone, and the gases and remaining steam migrate from the reactor through line 9 to a dedusting system and water washers and washing columns with aqueous caustic potash After the system has reached equilibrium, a stream of alkanesulfonic acid (about 70 to 85% by weight) mixed with aqueous HCl solution is withdrawn from the product recovery zone 10 through line 13. _ω

Although the reaction carried out here is expediently continuous in concentrated aqueous hydrochloric acid solution initiated and continued, the reaction can be initiated in pure water; However there is then a likelihood of ignition in the reactor until the HCl content in the aqueous Medium has discontinued.

As stated above, the feed rates of the reactants must be sufficient Have size to produce violent turbulence in the reaction zone, so that an intimate contact of the Reactants and a high product yield are guaranteed, while no mechanical stirring devices therein and the associated investment and maintenance costs are necessary. A loading

kung speed of at least about 13 kg / h of mercaptan or disulfide per 283 dm ^{3 of} the reaction zone

necessary to achieve these conditions. A practical upper limit on this feed rate ν

Speed is in the range of about 7.1 kg / h of mercaptan or disulfide per 283 dm ^{3 of} the reaction zone. The preferred /

The range is from about 13 to about 4.5 kg / h per 283 dm ³ . i: j It is convenient to carry out the process of the invention under atmospheric pressure or slightly below atmospheric ■: ■.

Carry out pressure lying pressures in order to facilitate the removal of gaseous by-products from the reaction zone ■; *. As stated above, alkanesulfonic acid is produced with negligible chlorination of the alkyl groups if the reaction described is within the temperature range from 85 to 115 ^° C.,

is preferably carried out at about 95 to 100 ° C for best conversion and yields. η

The following examples explain and illustrate the process according to the invention for the production '-

of alkanesulfonic acids. The processing equipment used in these experiments comprises a vertical pipe conveyor; |

migen glass reactor of 10 cm diameter and 254 cm length, with an overflow reservoir of about 10 cm 5 ;;

Diameter and 157 cm length through a horizontal return line at the bottom and an overflow line g

about 152 cm from the ground, each conduit being 7.6 cm in diameter. The Il

The volume of the reactor zone to the overflow line was about 1.21. The overflow reservoir (i.e. the product 1

recovery zone) contained a steam-heated heat exchanger fitted with pipe winds. The B

The liquid volume of the overflow reservoir was 1.7 1.1 The system was filled to strength to the overflow line with 20% aqueous HCl and heated to 95 to 100 ⁰ C | Gaseous chlorine was metered into the lower part of the reactor. Evaporated methyl mercaptan was poured into the

Metered into the reactor about 46 cm above the chlorine feed inlet. Water was in the side of the reactor Introduced near the bottom. The reaction was very violent, causing considerable turbulence in the reaction zone

was effected so that the turbulent reaction zone had a length of about 137 to 188 cm, equivalent to a ^ Volume from about 11 to 151. Unreacted chlorine and by-product HCl migrated from Upper part of the reactor came with a cooled heat exchanger with condensation of the water vapor

in contact and wandered through a dedusting or defogging system, a water washing column and. ^; : ·

a wash column with aqueous caustic alkali, from which the system was withdrawn into the atmosphere. After - ^

While the equilibrium conditions were maintained, an aqueous methanesulfonic acid product was continuously extracted from the. · '·' Overflow reservoir withdrawn. The operating data for various tests are given in the table below

reproduced. egg

: ί

Table r ' Experiment no. ¹

12 3 4 5; ■ ']

Ä

Methyl mercaptan feed rate kg / hr 1.64 1.64 1.64 1.64 6.58 S Chlorine feed rate, kg / hr 7.48 7.48 7.48 7.48 293 Amount of excess chlorine,% 2.6 3.0 3.0 3.0 23 Water feed rate, kg / h 1.85 1.85 1.85 1.85 73.2 Reactor ^{temperature, 0} C 100 115 100 115 100 Average response time, min <0, l <0, l <0, l <0, l <0, l Chemical analysis of the raw product Color, APHA value 0-5 15 40 70 100 Specific gravity at 25 ° C 1364 1367 1.439 1.446 1364 H ₂ SCm,% 0.09 0.08 trace none 0.04 Methanesulfonic Acid (MSA),% 70.06 71.80 84.3 8636 6838

HCl,% 2.21 1.00 1.27 0.46 1.61

Methanesulfonyl chloride (MSC), Vo 0.44 0.08 0.80 035 0.18

H ₂ O,% 27.45 27.66 14.89 13.47 29.79; '

Methanesulfonic acid production rate, 438 4.5 43 43 18.6 kg / h ΐ

Yield of methanesulfonic acid based on 983 98 97 963 96 Mercaptan,%;

- Κ

The aqueous 70-85% methanesulfonic acid "crude" product obtained from the above experiments si

was water-clear and suitable for use in the fields for which this compound and its lower |

Alkyl homologues are useful, for example as esterification catalysts, as catalysts for paints

compositions and coatings and as reaction solvents. ψ

A purified methanesulfonic acid (MSA) was produced, but using simple fractions - ||

tion (as described above) of the 70 to 85% strength product in a column with 15 trays with reduced Af

tern print (5 mm Hg. abs.) with a bubble temperature of 160 to 165 ° C and a head temperature of 153 ° G The 70-85% MSA contained small amounts of HCl, methanesulfone chloride (MSC) and trace amounts of H2SO4. After cleaning, the product was anhydrous, odorless, colorless, more than 993% strength MSA with a

specific gravity at 25 "C of 1.480.

1 sheet of drawings

Claims (1)

Patent claims: 1. Process for the continuous production of alkanesulfonic acids containing 1 to 4 carbon atoms in Have alkyl radical, characterized in that one - a) an alkyl mercaptan or dialkyl disulfide of the formula RSX, in which X is a hydrogen atom or a radical of the formula SR 'and R and R' are the same or different alkyl radicals having 1 to 4 carbon atoms mean with b) water round c) Chlorine, with chlorine in a stoichiometric amount up to an approximately 5% excess, based on alkyl mercaptan or dialkyl disulfide used, used,