Oleum, for sulfonation

By 1987, sulfur trioxide reagent use in the United States exceeded that of oleum for sulfonation. Sulfur trioxide source is divided between Hquid SO and in situ sulfur burning. The latter is integrated into sulfonation production faciUties. 

Later, improvements were made in the process use of oleum for sulfonating anthraquinone and the addition of an oxidizing agent to the caustic melL... 

Sulfonation. The main sulfonation product of quinoline at 220°C is 8-quinoHnesulfonic acid [85-48-3]-, at 300°C it rearranges to 6-quinolinesulfonic acid [65433-95-6] (10). Optimum conditions for sulfonation, 2 h at 140°C and a 1 4 quinoline/40% (wt) oleum ratio, produces 80% yield. The yield drops to 64% at 130°C with a 1 3 reactant ratio (11). Somewhat higher, but variable, yields of 8-quinoHnesulfonic acid hydrochloride [85-48-3] have been reported with chlorosulfonic acid (12). 

Sulfonation. Benzene is converted iato benzenesulfonic acid [98-11-3] C H SO, upon reaction with fuming sulfuric acid (oleum) or chlorosulfonic acid. y -Benzenedisulfonic acid [98-48-6] CgHgS20, is prepared by reaction of benzene-sulfonic acid with oleum for 8 h at 85°C. Often under these conditions, appreciable quantities ofT -benzenedisulfonic acid [31375-02-7] are produced. 1,3,5-Benzenetrisulfonic acid [617-99-2] C H S Og, is produced by heating the disulfonic acid with oleum at 230°C (21). 

The sulfonation of LAB can be carried out with concentrated sulfuric acid, oleum, or sulfur trioxide (S03). With the first two sulfonation reagents large quantities of waste sulfuric acid are obtained, which must be disposed of or processed further. Therefore the use of S03 is preferred. Special reactions were developed for sulfonation using S03 (Table 13). For sulfonation in batch pro-... 

The acid is prepared by sulfonation of nitrobenzene with oleum, and the reaction product consists essentially of a hot solution of the acid in sulfuric acid. A completed 270 1 batch exploded violently after hot storage at 150C for several hours. An exotherm develops at 145°C, and the acid is known to decompose at 200 C [ 1], A similar incident arose from water leaking from a cooling coil into the fuming sulfuric acid reaction medium, which caused an exotherm to over 150°C and subsequent violent decomposition [2], Detailed examination of the thermal decomposition of the acid shows that it is much slower for the isolated acid than for the reaction mass, and that the concentration of sulfur trioxide in the oleum used for sulfonation bears... 

Most of the problems of side reactions can be circumvented by using a mixture of unhydrous sulfuric acid (containing no free SO3, a powerful oxidant) and orthoboric acid [4,8], The superacidic nature of this sulfonation mixture ensures complete protonation and the lack of free SO3 excludes the possibility of oxidation. In addition, the number and position of the sulfonate groups can be more effectively controlled than by using oleum for... 

In a different approach [11] to access pure products, the use of strong oleum (65% SO3) for sulfonation of PPh3 resulted in quantitative formation of TPPTS oxide. This was converted to the ethyl suhbester through the reaction of an intermediate silver sulfonate salt (isolated) with iodoethane. Reduction with SiHCls in toluene/THF afforded tris(3-ethylsulfonatophenyl)phosphine which was finally converted to pure 3 with NaBr in wet acetone. In four steps the overall yield was 40% (for PPhs) which compares fairly with other procedures to obtain pure TPPTS. Since phosphine oxides are readily available from easily formed quaternary phosphonium salts this method potentially allows preparation of a variety of sulfonated phosphines (e.g. (CH3)P(C6H4-3-S03Na)2). 

Sulfonation of isoquinoline with 40% oleum or higher S03 content, at temperatures up to 180 °C, gives isoquinoline-5-sulfonic acid (20) as main product. At higher temperatures the 8-sulfonic acid is also formed. Sulfonation of 4-hydroxyisoquinoline with 20% oleum for six hours at 200 °C gives the 8-sulfonic acid (21 Scheme 14) (72IZV457). 

Batch Stirred Tank H2S04/Oleum Aromatic Sulfonation Processes. Low molecular weight aromatic hydrocarbons, such as benzene, toluene, xylene, and cumene, are sulfonated using molar quantities of 98—100% H2S04 in stirred glass-lined reactors. A condenser and Dean-Stark-type separator trap are installed on the reactor to provide for the azeotropic distillation and condensation of aromatic and water from the reaction, for removal of water and for recycling aromatic. Sulfone by-product is removed from the neutralized sulfonate by extraction/washing with aromatic which is recycled. 

Naphthylamine is usually vacuum distilled in the plant. The distillation must be done very carefully, since the compound decomposes easily. For sulfonation reactions, if the free base is not isolated, the thoroughly dried sulfate, mixed with 1 per cent soda (see also primuline), is added to sulfuric acid or oleum. 

Reaction temperature is often important in determining the ratio of mono- to polysulfonates. This is clearly illustrated in the commercial process for sulfonating 4-aminoazobenzene with a fixed quantity of oleum, as shown in Table 7-10. ... 

Conventional Process for Production of Naphthalenedisulfonk Acid. The standard process for sulfonating aromatic hydrocarbons uses sulfuric acid and oleum as reactants. Under these conditions, the reaction vessels can be made out of gray cast iron, and steel can be used for piping and fittings. 

This is confirmed, for instance, when the obtainable product quality, energy and utilities demand, and raw material consumption for LAS production are comparatively taken into account for oleum-and SOj-based processes, as shown in Table 5.8. For the oleum-based sulfonation plant, the spent acid represents an important variable (either for its neutralization or simple disposal for further SOj recovery) with heavy impact on the process cost. Moreover, the availability and cost of oleum derived from local situation that, case by case, might contribute to make this sulfonating agent comparatively cheaper than the more modern, clean, efficient, and versatile gaseous SO3. 

Another method for sulfonation involves the use of oleum, a solution of SO3 in snifnric acid. The process is similar to the use of sulfuric acid, but this process generates less water than aU of the sulfuric acid processes and so should, in principle, be faster. However, sulfone generation is generally higher than with sulfuric acid. 

Alkanes are easily oxidised by sulfur trioxide, oleum and chlorosulfonic acid consequently, attempted sulfonation of an n-alkane by such reagents generally leads to a complex mixture of products and the yields of the alkanesulfonic acids are very low. Chlorosulfonic acid has, however, proved useful for sulfonating low pressure polyethylene film. The ease of replacement of the hydrogen atoms of an alkane by the sulfonic acid group follows the order ... 

A useful mild method for sulfonation of aromatic polymers involves dissolving them in chlorosulfonic acid or oleum, adding an inert organic solvent, e.g. dichloromethane, followed by a carboxylic acid anhydride, e.g. acetic anhydride and allowing the sulfonation to proceed at a temperature of < 25 °C. 

Oleum and sulfur trioxide are used routinely for sulfonation, with the latter growing in popularity in recent years. Oleum sulfonation requires relatively inexpensive equipment and can be accomplished by either batch or continuous processes. However, the oleum process has major disadvantages in the SO3 cost/lb (as H2SO4), the need for spent acid stream disposal, and potential corrosion problems due to sulfuric acid generation. The oleum process typically yields an 88 to 91 percent purity sulfonic acid with the remainder consisting of approximately 6 to 10 percent H2SO4, 0.5 to 1.5 percent water, and 0.5 to 1.0 percent unsulfonated oils. Reactions involved in oleum sulfonation are shown below. 

TBPA is prepared in high yield by the bromination of phthalic anhydride in 60% oleum (51). The use of oleum as the bromination solvent results in some sulfonation of the aromatic ring (52). Sulfonated material is removed by hydrolyzing the anhydride with dilute NaOH, filtering and acidifying with dilute HCl. The precipitated acid is washed several times with hot water and reconverted to the anhydride by heating at 150°C for several hours. 

Another example of manufacture in this series is the sulfonation of an aminonaphthalenesulfonic acid, followed by selected desulfonation, to make 6-amino-l,3-naphthalenedisulfonic acid (21). Thus, 2-amino-l-naphthalenesulfonic acid made by amination of 2-hydroxy-1-naphthalenesulfonic acid is added to 20 wt % oleum at ca 35°C. At this temperature, 65 wt % oleum is added and the charge is stirred for 2 h, is then slowly heated to 100°C and is maintained for 12 h to produce 6-amino-l,3,5-naphthalenetrisulfonic acid. The mass is diluted with water and maintained for 3 h at 105°C to remove the sulfo group adjacent to the amino group. After cooling to ca 20°C and filtration, 6-amino-l,3-naphthalenedisulfonic acid is obtained in 80% yield (55). 

Petroleum sulfonates have traditionally been produced by both batch and continuous treatment of petroleum oils with oleum. These processes have been covered in several reviews (138,139). Natural petroleum sulfonates are coproducts in the manufacture of a variety of refined oils, most notably white (mineral) oils, lube oils, and process oils (plasticizer oils for mbber compounding). The feedstocks are selected primarily on the basis of the desired characteristics of the refined oils which generally contain 15—30% aromatics. 

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