Acetone-1,3-disulfonic acid

This represents a two-step hydrolysis. In the first phase, it requires anhydrous reactants to avoid the formation of a-hydroxylamide, which is more difficult to convert to methacrylamide sulfate. It takes place in liquid medium, at atmospheric pressme, first at about 80 to 110°C, and then 125 to 145°C to complete the transformation, nidi residence tones of about 1 h, an HjSO /acetone cyanohydrin molar ratio of 1.5 to 2, and a molar yield of 95 to 97 per cent The main by-products are carbon monoxide and acetone disulfonic acid. It is necessary to operate in the presence of an inhibitor (phenol, phenothiazme, sulfur, etc.) to prevent the formation of polymers. 

Acetone (propan-2-one) 75 reacted with chlorosulfonic acid in dichloromethane at low temperature (< 20 °C) followed by refluxing the mixture (3-3 hours) to give the 1,3-disulfonic acid 76, 75-100% yield. The disulfonation occurs via enolization of the ketone as depicted in Scheme 6. 

In general, bulky substituents at the 3,3 -position of the BINOL backbone are required to achieve good selectivities in asymmetric catalysis. This laborious catalyst fine-tuning can be simplified when chiral l,r-binaphthyI-2,2 -disulfonic acid (BINSA, 141) is used instead of the aforementioned BINOL-derived chiral phosphoric acids. Complexation with a suitable achiral amine enables to tune the bulkiness and Brpnsted acidity in situ [98]. Based on this approach, Ishihara and coworkers combined various A-Boc- or A-Cbz-protected imines and acetyl acetone in the presence of BINS A (1 mol%) and 2,6-diphenylpyridine (142, 2mol%) to afford the corresponding Mannich products in excellent yields and enantioselectivities (Scheme 11.31) [98]. However, the cata-... 

Diammonium l,3-diazaadamantan-6-one-5,7-disulfonate is obtained by heating an aqueous solution of diammonium propanone-1,3-disulfonate (prepared easily by sulfonation of acetone with fuming sulfuric acid) and hexamethylenetetramine.82 Other several l,3-diazzadamantan-6-one derivatives are prepared similarly.83-86... 

Preparation. Sodium hydroxylamlne disulfonate (1), prepared by passing sulfur dioxide into an aqueous solution of sodium nitrite and sodium bisulfite, reacts with acetone to form acetoxirae (2) acid hydrolysis affords hydroxylamlne hydrochloride. 

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