A-Hydroxysulfonic acids

Fig. 2-29. Formation of a-hydroxysulfonic acids after addition of hydrogen sulfite ions to aldoses. R = the monosaccharide residue.

Fig. 7.7. Sulfonation of coniferaldehyde end groups and substituted structures containing a-carbonyl groups (see Gellerstedt, 1976). At lower temperatures aldehyde end groups can bind sulfur dioxide because of the formation of a-hydroxysulfonic acid.

In the course of the reactions described in section (I) the complex silver and bismuth ions are reduced to the metal by the -CHO group of the aldehyde. No reaction occurs if this group is not present (paraldehyde). In reaction (II) the SO3 group of the fuchsinesulfurous acid is split off and adds to the aldehyde to form an a-hydroxysulfonic acid. The color of the fuchsine itself is now visible. All the normal reactions of an aldehyde are observed if acetaldehyde is set free from its trimer paraldehyde. Sulfuric acid catalyses both the forward and back reactions in this equilibrium (eqn. 1) ... 

Incorporation of methanol at the rate of 2 kg/kg phosphorus pentoxide in the dried acidulate significantly improves the purity of the phosphoric acid product in a two-stage process. This modification is especially advantageous with a low-grade phosphate rock [42]. Acetone has also been found of value in an experimental variant which enables much less expensive sulfurous acid, rather than sulfuric acid, to be used as the acidulant [43]. In this case, the solvent forms an a-hydroxysulfonic acid with the sulfurous acid (Eq. 10.27) which is sufficiently strong to attack phosphate rock at a reasonable rate. 

The formation of the a-hydroxysulfonic acids is influenced by concentration of the reactants (carbonyl compound and bisulfite), temperature, and pH. The rate of association as influenced by the relative concentration of bisulfite, aldehyde, and sugars was investigated early by Kerp (1904) and his collaborators and others, and more recently by Ingram and Vas (1950b) and by the Corn Products Refining Company. The effect of pH and temperature on dissociation of the sulfonic acids has been investigated also for some of the compounds (see the review by Suter,... 

For a considerable period following its discovery, sodium formaldebvde bisulfite was belie ed to possess the structure of a hydroxy sulfite ester, HOCHiOSOoNa. This formula was incorrect, and it has now been established that its stnictuie is that of a hydroxysulfonic acid, HOCHiSOsKa. This structure is based on the studies of Raschig and Prahl i> 2 in 1926-8 and Lauer and Langkammerer in 1935. 

Castor oil sulfation results largely in a sulfuric acid ester in which the hydroxyl group of ricinoleic acid has been esterified. However, other reactions can also take place. For example, the double bond can be attacked to produce an ester or the hydroxysulfonic acid (33). Hydrolysis of the sulfuric acid esters occurs during the reaction and subsequent treatment forming hydroxy acids and sulfuric acid. These hydroxy acids can be further sulfated. 

Reaction of the hydroxy disulfide 95 with concentrated nitric and sulfuric acids has been used to obtain the oxathiolanyl nitrates 96 and 97 (Equation 13) <1997W046521>. A new synthesis of 3-methyl-l,2-oxathiolane 2,2-dioxide 99 involved reaction of crotonaldehyde (MeCH=CH-CHO) with SO2 and water followed by catalytic hydrogenation to give the hydroxysulfonic acid 98 which was then dehydratively cyclized to give the product in 52% overall yield (Equation 14) <1996MI18>. 

Sodium hydrogen sulfite also adds to aldehydes and some ketones to form hydroxysulfonic acids (22) (Scheme 20). The nucleophilic addition generally goes well with aldehydes and methyl ketones of the type RCOMe, where R is a primary alkyl group. Since the water soluble products are readily converted back to the carbonyl compounds by treatment with dilute acid, the reaction provides a useful method for purification of carbonyl compounds from non-carbonyl impurities. 

The cyclisation of aromatic hydroxysulfonic acid derivatives has been widely used to obtain aromatic sultones like (158) and (159). The reaction involves sulfur-oxygen bond formation and is effected by a wide variety of reagents, e.g. H2S04, PCI5, POCI3 and CIS03H (Scheme 65).8... 

The reaction of simple olefins with S03 and S03 complexes and derivatives has been demonstrated to yield allylic and vinylic sulfonic acids, hydroxysulfonic acids, and other neutral products (10). The product distribution is a function of olefin type, sulfonation reagent, solvent, and reaction conditions. 

The a-hydroxysulfonates are not oxidized by iodine in neutral or acid solutions, but this does occur in alkaline solutions where it is preceded by dissociation into the free sulfite. They are also not readily oxidizable by oxygen. 

Total SulfuT Dioxide After Alkali Treatment The fact that neutral sodium sulfite does not combine with carbonyl compounds and that the hydroxysulfonic acid compounds are rapidly decomposed on treatment with alkali was used by Ripper (1892) as the basis for the determination of total sulfur dioxide in wine by direct iodine titration. In his method, 50 ml. of wine were pipetted into a 200-ml. flask containing 25 ml. of 1 iV KOH. The mixture was shaken and allowed to stand for 10 to 15 minutes. Then 10 ml. of dilute sulfuric acid (1 + 3) were added, and the solution titrated rapidly with 0.02 N iodine solution to a starch end point which persisted for some time. This method was used as the ofiicial direct titration method for wine in the first edition (1919) of the A.O.A.C. Methods of Analysis in the third (1930) edition it was extended to white grape juice, wine, and similar products (1N NaOH or KOH was used and the solution during standing for 15 minutes was occasionally agitated) hut it was dropped from the fourth (1935) and succeeding editions. Ripper compared his method with the Haas distillation method on ten wines whose SO2 content varied from 42 to 1488 mg. per liter and found the difference between the two to vary from 0 to 5 mg. 

Hydroxysulfonic acids. An aq. soln. of 5-cyclohexylamino-5-deoxy-l,2-0-iso-propylidene-D-xylofuranose satd. with SOg for 7 days at 25° by passing in a slow stream of SOg -> product. Y 71.2%.—This method provides protection for sensitive carbonyl groups, which are otherwise degraded, and enables in certain cases the isolation of crystalline bisulfite addition compounds. F. e. s. D. L. Ingles, Chem. Ind. 1964, 927. 

To a mechanically stirred, cooled (-5°5°C) solution of 6-methyl-7,7-dioxo-4,5,6,7-tetrahydro-776-trieno-[2,3b]thiopyran-4-ol (hydroxysulfone) (25.0 g, 0.114 mol 98 2 trans/cis) in acetonitrile (300 mL) was slowly added concentrated sulfuric acid (18 M, 86 mL, 1.52 mol) over a 0.5 h period while maintaining the internal temperature at -5°-5°C. The mixture was allowed to warm to 20°5°C and was stirred at this temperature for 12-18 h, or until the reaction was judged to be complete by HPLC. The reaction was considered complete when less than 1% of hydroxysulfone remained. At the end of the reaction the trans/cis ratio of the acetamidosulfone - (N-(6-methyl-7,7-dioxo-4,5,6,7,-tetrahydro-776-trieno-[2,3b]thiopyran-4-yl)propionamidewas 92.4 7.6. 

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