Selective sulfonations, sulfur trioxide

The older methods have been replaced by methods which require less, if any, excess sulfuric acid. For example, sulfonation of naphthalene can be carried out in tetrachloroethane solution with the stoichiometric amount of sulfur trioxide at no greater than 30°C, followed by separation of the precipitated l-naphthalenesulfonic acid the filtrate can be reused as the solvent for the next batch (14). The purification of 1-naphthalenesulfonic acid by extraction or washing the cake with 2,6-dimethyl-4-heptanone (diisobutyl ketone) or a C-1—4 alcohol has been described (15,16). The selective insoluble salt formation of 1-naphthalenesulfonic acid in the sulfonation mixture with 2,3-dimethyl aniline has been patented (17). 

Sulfur trioxide reactivity can also be moderated through the use of SO adducts. The reactivity of such complexes is inversely proportional to their stabihty, and consequentiy they can be selected for a wide variety of conditions. Whereas moderating SO reactivity by adducting agents is generally beneficial, the agents add cost and may contribute to odor and possible toxicity problems in derived products. CeUulosic material has been sulfated with SO.—trimethyl amine adduct in aqueous media at 0 to 5°C (16). Sulfur trioxide—triethyl phosphate has been used to sulfonate alkenes to the corresponding alkene sulfonate (17). Sulfur trioxide—pyridine adduct sulfates oleyl alcohol with no attack of the double bond (18). 

P 2] [R 18, modified] [C 2] To-date, the reaction has been carried out up until the residence-time module. The final hydration step [Figure 4.44, reaction (4)] has not taken place. Even so, the first results are very encouraging as shown in Figure 4.46. In order to evaluate the reaction conditions, the mole ratio of the two reactants, sulfur trioxide and toluene, was varied and the selectivity of the desired product (sulfonic acid) and of the by-products (sulfone and the anhydride mixture) was determined. Evidently, with increasing S03/toluene mole ratio, the selectivity of the undesired by-products decreases whereas the selectivity of sulfonic acid stays nearly constant. At a mole ratio of 13/100, the selectivity of sulfonic acid is approximately 80% whereas that of sulfone decreases to approximately 3% and that of the sulfonic acid anhydride to approximately 1.3%. 

Two novel reagents for the selective sulfonation of styrene to the (3-sultone (49) are reported (94ZOR948). The action of sulfur trioxide on the olefin CF2 CFS03SiMe3, yields the p-sultone (50) (94JFC89). 

Figure 4.51 Selectivity for toluene sulfonation in a special microplant with falling-film microreactor, when increasing contents of sulfur trioxide are fed (by courtesy of Elsevier) [315],...

Sulfonated polyalkenes were conveniently prepared by using a triethyl phosphate-sulfur trioxide 1 1 complex as sulfonation reagent. This complex is versatile in use, as it can be attenuated to a selective reaction by adjusting the ratio of the two components. Thus Rahrig and Macknight28 used it in chloroform, at room temperature, in preparing sulfonated poly(pentenamers) and their sodium salts (PPS03Na)... 

The desired higher selectivity of the sulfonation reaction cannot be achieved by using sulfuric acid as a reaction medium but rather by dissolving the reactants, naphthalene and sulfur trioxide, in an organic solvent (chlorinated hydrocarbon, QIC) and reacting them at temperatures lower than those of the previous process [148]. 

The petroleum sulfonates were also prepared by sulfonating gas/oil fractions with sulfuric acid in the 1970 s. The main disadvantage of this process was sluge disposal. Therefore, the gas/oil fractions were sulfonated with sulfur trioxide in order to eliminate the sluge disposal problem. The process was not cost-effective. Thus, crude oil was selected to sulfonate with sulfur trioxide. A few years later. Marathon Oil Company manufactured petroleum sulfonates by a crude oil sulfonation process. These petroleum sulfonates have been employed in several EOR field projects in the United States. 

Van de Vusse [1] pointed out that selectivity with respect to I increases with an increase of the mass transfer coefficient (k ). In light of this observation, we have developed a new reactor of cyclonic type in which, due to strong centripetal forces on the gas bubbles, a very high k is realized [2]. This paper deals with the selectivities obtained in sulfonation of benzene with sulfur trioxide. Both neat benzene and benzene diluted with 1,2-dichloroethane were used. This reaction was selected as a model reaction for industrially important aromatic sulfation (e.g. detergents). We studied the reaction in three reactor types that greatly differ in mass transfer characteristics, i.e. in a stirred ceii reactor (low k ), a co-current gas-liquid tube reactor (intermediate k ) and in the cyclone reactor (high k ). 

In the sulfonation of unsaturated alcohols, powerful sulfonating reagents tend to attack the double or triple bond as well as the hydroxyl group consequently, milder reagents are preferred for selective O-sulfation. Studies of the sulfation of oleyl and elaidyl alcohols showed that the purest product (97% purity) was obtained using chlorosulfonic acid-urea, followed by sulfur trioxide-pyridine (96%), sulfamic acid (93%), sulfur trioxide-dioxan (90%) and chlorosulfonic acid-sodium chloride (60%). With sperm oil, the use of chlorosulfonic acid-urea afforded 99% sulfation with 90% retention of the double bond. ... 

A one-pot synthesis of alkyl perfluoroalkyl ketones has been developed. Phosphoranes, generated in situ, are acylated with a perfluoroacyl anhydnde, and the resultmg phosphonium salts are hydrolyzed with alkali [4S (equation 48) Hydrolysis of a carbon-sulfur bond in 2-chloro-2,4,4-trifluoro-1,3-dithietane-S-trioxide, which can be obtained from 2,2,4,4-tetrachloro-l,3-dithietane by fluor-mation with antimony trifluoride followed by selective oxidations, opens the nng to produce 2-chloro-1,1,2-trifluorodimethyl sulfone [49] (equation 49)... 

---