O-Sulfobenzoic anhydride

Hydroxy-phosphines undergo benzoylation with o-sulfobenzoic anhydride in the presence of bases (Na2C03 or BuLi) affording sulfobenzoylated phosphine products. In such a way several mono- and dihydroxy phosphines could be made soluble in water, exemplified by the chiral bisphosphines 53. It should be noted, that this general method allows the preparation of water-soluble sulfonated derivatives of acid-sensitive phosphines, such as DIOP, too, which are not accessible via direct sulfonation [56]. 

Phthaleins. Dyes of this class are usually considered to be triarylmethane derivatives. Phenolphthalein [77-09-8] (23, R = CO) and phenol red [143-74-8] (23, R = S02) are used extensively as indicators in colorimetric and titrimetric determinations (see Hydrogen-ion activity). These compounds are prepared by the condensation of phenol with phthalic anhydride or o-sulfobenzoic anhydride, respectively, in the presence of a dehydrating agent. 

The peracid is prepared in 65-75 % yield by the reaction between o-sulfobenzoic anhydride and 30% hydrogen peroxide in acetone solution at —4 to 0°C. The solution is used directly for epoxidation of olefins. Since the reagent contains a strongly acidic group, the initially formed epoxide undergoes acid cleavage to a truns-diol unless a solid buffer such as sodium carbonate is present. The peracid can also be used for Baeyer-Villigcr oxidation and for oxidation of heterocyclic t-amines to N-oxides. ... 

Benzyne is produced in the vapor phase by the fragmentation of phthalic anhydride and of o-sulfobenzoic anhydride (11) at 690°C,17 also of 4-phenyl-1,2,3-benzotriazine (12),18 phthaloyl peroxide (13),19 and a variety of other cyclic systems at appropriately high temperatures. From the point of view of studying the reactions of benzyne with heterocycles, these methods are necessarily restricted in their application. 

The preferred bases include triethylamine, amidines, and guanidines. Dehydration of the carbamate has been done with phosphorus trichloride, phosphorus oxytrichloride, phosphorus pentoxide, acetic anhydride, benzenesulfonic acid anhydride, o-sulfobenzoic anhydride (2.14), or other similar compounds. 

Scheme 2 Reaction of bis[2-(diphenylphosphino)ethyl]amine-HCI with o-sulfobenzoic anhydride.

An additional access to chiral sulfonated phosphines was also described [13a,b]. The method is based on the acylation of chiral hydroxyphosphines with commercial o-sulfobenzoic anhydride and was demonstrated on a number of diphosphines based on the DIOP skeleton (Eq. 1). The chelating properties of the diphosphines were studied by preparation of cationic rhodium complexes. The presence of the o-sulfobenzoate group is thought not to influence the catalytic properties. Chiral phosphines containing a sulfonate group (e.g., 8) were also obtained from BPPM by acylation with trimellitic anhydride followed by treatment with sodium tauri-nate [13 c],... 

It should be finally noted that hydroxyphosphines can be converted under very smooth conditions into sulfonated phosphines by acylation with o-sulfobenzoic anhydride, as shown by Borner et al. (Eq. 5) [26]. With this methodology in hand the severe conditions commonly used for the incorporation of sulphonate groups in phosphines can be avoided. Acid-labile functional groups like acetals survive under these conditions. In comparison to the parent hydroxyphosphines the water solubility of the relevant Rh catalysts was strongly enhanced [27]. In the asymmetric hydrogenation of prochiral olefins, moderate enantioselectivities were achieved. 

It is not possible to introduce further iodine atoms into 3,5-dihalo-2- or -4-hydroxybenzoic acid by the oleum method. However, in 60% oleum it is possible to halogenate o-sulfobenzoic anhydride and thus to obtain the 3,4,5,6-... 

Benzyne is produced in the vapor phase by the fragmentation of phthalic anhydride and of o-sulfobenzoic anhydride (11) at 690°C/ also of 4-phenyl-... 

Sulfonates, Tosylates -Trichloromethyl- -ethanesultone o-Sulfobenzoic anhydride... 

S0Hal2, SOCI2, SOBr2 o-Sulfobenzoic anhydride TS2O... 

Figure 2.6 Reaction mechanism of polyaniline with o-sulfobenzoic anhydride (Reprinted with permission from Macromolecules, 33, 8117. Copyright (2000) American Chemical Society.)...

Although the major fragmentation pathway of o-sulfobenzoic anhydride (76) in its 70-eV mass spectrum involves loss of SO3 and CO, upon thermolysis SO2 and CO2 are lost to give benzyne (i), - Some evidence was found for the intermediacy of the zwitterion 77. ... 

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