Bisulfite salts

The crude product is readily purified by conversion to its hydrochloride salt. The bisulfite salt is transferred to a wide-mouthed 1-1. flask, and concentrated hydrochloric acid is added until the consistency of the resulting mixture is such as to permit mechanical stirring (100 to 200 ml. of acid). The slurry is heated on a steam bath with stirring for 1 hour Hood ). The tan diaminouracil hydrochloride is filtered on a sintered glass funnel, washed well with acetone, and vacuum-dried over phosphorus pentoxide. The yield of diaminouracil hydrochloride is 104-124 g. (68-81%) (Notes 6 and 7). 

The preparation may be interrupted after the nitroso compound has been separated or after the crude bisulfite salt has been isolated. This preparation has been satisfactorily carried out on a scale seven times that given. 

The procedure for the formation of diaminouracil bisulfite is slightly modified from that of Cain, Mallette, and Taylor,2 which in turn is derived from preparations of Bogert and Davidson,8 and Traube.4 The sulfate salt may be formed in lower yield than the hydrochloride described here by dissolving the bisulfite salt in aqueous base and precipitating with sulfuric acid.8-4 The hydrochloride is appreciably soluble in water, while the sulfate salt is only slightly soluble. 

Sulfite and bisulfite salts eulfinace acid salt ... 

From prior calibrations we found that pH of the solution denoted the sulfite/bisulfite salt ratio and conductivity data were related to the concentration of salts in solution. From these data the quantity of ammonia that was regenerated could be calculated. A calculated ammonia balance over the first 83 hr of operation showed 4.23 gram-moles ammonia loss from all causes, which is representative of a maximum stack loss of 3.53 ft of ammonia. Since a total of 41,500 ft of gas was processed, ammonia loss was about 85 ppm. On a once-through basis this represents about... 

Similarly, an aqueous treatment for wool uses an isocyanate blocked with a bisulfite. In this case, the by-product bisulfite salt can be removed, and possibly recycled, by washing the fabric with water at the end. The dissociation temperature decreases in the following order alcohol > lactam > phenol > ketoxime > active methylene compound. e-Caprolactam is a typical lactam, ethyl acetoacetate a typical active methylene compound. This thermal reversibility has been used to prepare a polyurethane from 1,4-butanediol, 4,4 -diphenyldiiso-cyanate, and 4,4 -isopropylidenediphenol (bisphenol A) (2.30) that can be recycled just by remolding.76... 

Sodium bisulfite-blocked isocyanate-terminated prepolymers are extensively used as shrink-resistant finishes for wool. Polycarbamoylsulfonates (PCS) are produced from NCO-terminated prepolymers with bisulfite salts in aqueous alcohol as the solvent, shown schematically as follows (78-80) ... 

Giveu the issues associated with the bisulfite process, a new process was developed in which the free aldehyde was first liberated from its bisulfite salt under basic (NaOH) conditions in... 

Schone 3.30 NHC-catalyzed biphasic Diels-Alder reactions of chloroaldehyde bisulfite salts with oxodienes... 

The production uses a different method than the more common sulfonation systems such as chlorosulfonic acid, sulfur trioxide, pyrosulfate, or oleum. The Streckerization reaction utilizes a mixture of sulfite and bisulfite salts to sulfonate the ether intermediates into the final surfactant. The most commonly used process for the production of these surfactants is a multistep batch system, where each reaction step is performed in separate reactor. This prevents contamination of one step to the next as well as the introduction of certain species, which are a benefit to one step but a detriment to another—specifically water. The batch system s agitation allows for good mixing between two immiscible liquids, which is a common theme throughout the production. Although batch systems are the most common, the process can be adapted for continuous production. 

The end product yielded by this process is DL-a-methyldopa, a racemate. The antihypertensive effect, however, is exerted solely by the L-(-)-isomer. The isomers can be separated with the aid of 1-phenethylamine at the stage of dl-3-(3, 4 -dimethoxyphenyl)-2-methylalanine, or with the aid of quinine at the stage of DL-a-methyldopa [255]. Both procedures are too expensive for large-scale production. The industrial process used today is fractionated crystallisation [276]. For this purpose, DL-a-methyldopa is dissolved in water in the form of the bisulfite salt and the l-(—)-isomer is crystallised from the supersaturated solution by inoculation with pure L-(—)-a-methyldopa. 

Menadione, or vitamin K3 (VK3), is the synonym for 2-methyl-l,4-naphthoquinone, and does not occur in nature. It has to be synthesized, and acts as an intermediate in synthesis of K vitamins. VK3, as a provitamin, can be transformed to MK4 by micro-organisms. Menadione has been shown to exhibit antitumor activity in rodent and human tumor cells (6-9). A water-soluble form of the provitamin VK3 (menadione sodium bisulfite, MSB see Structures 6 and 7 in Fig. 1) is often added to animal feed, and after treatment with aqueous Na2C03 (destroying the bisulfite salt) and/or irradiation with UV-radiation (10), it can be chromatographed and analyzed in usual ways. 

The lignosulfonate counterion is determined by the bisulfite salt used together with sulfurous acid during pulping of the wood chips. It is possible via different ion-exchange processes to change the counterion. 

Scheme 38.35 Hetero-Diels-Alder reactions with a-chloroaldehyde bisulfite salts.

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