Sulfonate reaction

Sulfones are a constituent of free oil at a level of —25-33% and cannot be eliminated by aging or any other step, i.e., sulfone competes directly with the desired main reaction. Sulfone formation is promoted by the following conditions ... 

POLYCONDENSATION REACTION INCIDENTS, POLYMERISATION INCIDENTS, REDOX REACTIONS, SULFONATION INCIDENTS... 

Sulfonation is easily reversible. Simply diluting the fuming sulfuric acid leads to the removal of the -SO3H. This is an important synthetic technique for protecting certain sites from reaction. Sulfonation can act as a placeholder while other reactions are performed, and then the easy removal of the sulfonic acid group makes the site available for reaction in a later step in a series of reaction steps. 

In order to obtain further insight into the mechanism of the Mannich-type reaction, sulfone IP and silyl enol ether derived from acetophenone were reacted in the presence HOTf or TMSOTf, which could be produced in the reaction medium when using Bi(0Tf)3-4H20 as catalyst. It appeared that these two compounds efficiently catalyze the Mannich-type reaction (Table 7, entries 2 and 3). The reaction does not occur in the presence of 2,6-di-/<7V-buty I-4-methyl-pyridine [DTBMP] (1.0 equiv. of lp, 1.3 equiv. of silyl enol ether, 0.5 mol% of Bi(0Tf)34H20, 1.5 mol% of 2,6-di-/c/V-buty l-4-methy I-pyridine, 22 °C, 20 h, 99% recovery of lp), which indicates that triflic acid is involved in the mechanism (Table 7, entry 4). 

In 2009, Onda et al. studied the catalytic activity of sulfonated activated carbon prepared from active carbon and concentrated sulfuric acid [47]. The hydrolysis was performed under hydrothermal conditions at 423 K in a steel autoclave lined with Teflon. After 24 h of reaction, sulfonated carbon afforded high yield of glucose (40 C-%, i.e., based on the total weight consumption of carbon) and nearly no SO4 elution was observed which clearly indicated that the process was heterogeneously catalyzed. As observed above, under hydrothermal conditions, the glucose yield... 

NITRATION INCIDENTS OXIDATION INCIDENTS PEROXIDATION INCIDENTS PLANT CLEANING INCIDENTS POLYCONDENSATION REACTION INCIDENTS POLYMERISATION INCIDENTS REDOX REACTIONS SULFONATION INCIDENTS... 

Hydroxypyridines undergo a variety of other electrophilic substitution reactions. Sulfonation of 2-pyridone with 10% oleum at 180° gave the 5-sulfonic acid.69 110 A-Methyl-2-pyridone is similarly sulfonated with chlorosulfonic acid. The action of fuming sulfuric acid gave a mixture of the 5-sulfonic acid and the 3,5-disulfonie acid. A nitro group at C-5 is said not to hinder the reaction, sulfonation at the... 

Exothermic Gas Absorption with Complex Reaction Sulfonation and Discoloration in the Absorption of Sulfur Trioxide in Dodecylbenzene... 

Most heterocyclic nuclei undergo the sulfonation reaction. Sulfonation of pyridine is difficult. The yield of 3"pyridinesulfonic acid by sulfonation at 390° with oleum is only 13%. The yield is greatly improved by the use of vanadium or mercury salts as catalysts. A critical study of the factors influencing the yield has been made, and a maximum yield of 71% is reported. Fuming sulfuric acid converts quinoline to practically pure 8-quinolinesulfonic acid (54%). The action of concentrated sulfuric acid on dibenzofuran gives 2-dibenzofuransulfonic acid (75%). ... 

Sulfonation or chlorosulfonation using fuming sulfuric acid or chloro-sulfonic acid are useful reactions. Sulfonations are often reversible and hence the sulfonate group may be used to protect a particular site on an aromatic ring. It can then be removed later in a synthetic sequence. 

Unlike most other electrophilic substitution reactions, sulfonation shows a moderate isotope effect ordinary hydrogen (protium) is displaced from an aromatic ring about twice as fast as deuterium. Docs this mean that sulfonation takes place by a different mechanism than nitration, one involving a single step Almost certainly not. 

Unlike most other electrophilic substitution reactions, sulfonation is reversible, and this fact gives us our clue. Reversibility means that carbonium ion II can lose SO3 to form the hydrocarbon. Evidently here reaction (2) is not much... 

Solid acids are widely used to catalyze electrophilic reactions. Sulfonated styrene-divinylbenzene cross-linked polymers are efficient solid acids. These resins, such as Dowex 50, Amberlite IR-112 and... 

Sulfonation of nitroso compounds by sodium hydrogen sulfite leads to amino sulfonic acids by simultaneous reduction.1240 194 When aromatic nitro compounds are subjected to this reaction, sulfonation in the ring is accompanied by formation of arylamine-JV-sulfonic acids (arylsulfamic acids), which on acid fission also give amino sulfonic acids this reaction, known in the literature as the Piria reaction, has been reviewed in papers by Hunter and his co-workers.195... 

Aromatic sulfonation, like nitration, balogenation, alkylation, and acylation, is a typical electrophilic substitution reaction. Sulfonation, however, differs from these other reactions in two marked respects it is reversible, and reaction temperature can, in certain cases, have an important influence on the position of the entering group, as shown on p. 344. These characteristics have tended to complicate studies of the reaction mechanism and rate of sulfonation and to render difficult the drawing of general conclusions. Other factors having the same effect are the tendency of sulfur trioxide to form a complex with the sulfonic acids and the pronounced tendency of all Lubs, pp. 534ff. 

The greater reactivity of pyridine-1-oxide towards nitration as compared to pyridine is noteworthy. It proceeds smoothly in nitrating acid, via the free base and the a-complex 77, yielding 4-nitropyridine-l-oxide 78 (see p 274). Other Sg reactions (sulfonation, halogenation) require drastic conditions. 

Important reactions include sulfur as nucleophile and leaving group in the 5 2 reaction, sulfonation of aromatic rings (Chapter 21), and formation and reduction of thioacetals (Chapter 23). This Sn2 reaction uses a sulfur nucleophile and a sulfur-based leaving group. 

The very mechanisms of sulfonation of high polymers have been reviewed by Kucera and Janc. The sulfonation reaction proceeds easily in the presence of groups, such as —Cl, —NH2, —OH, —SH, etc. In fact, the active agent in the sulfonation reaction is the SO3 cation. The sulfonation of aromatic compounds is a reversible reaction. Sulfonating agents can be classified into three groups, namely... 

Muller et al. [30] used the sulfonation of toluene with gaseous SO3 as a reaction to characterize and test a microreactor plant based on a standardized microfluidic platform for laboratory and small-throughput production purposes. The reaction paths during sulfonation of toluene with gaseous SO3 are given in Figure 22.19. Sulfonic acid is the desired product, which is formed via the direct reaction of toluene and SO3 [reaction (23.1)]. In a consecutive reaction, sulfone [reaction (23.2)] is formed, which cannot be converted further. Also, a mixed anhydride and sulfonic... 

Carboxylate anions derived fi om somewhat stronger acids, such as / -nitrobenzoic acid and chloroacetic acid, seem to be particularly usefixl in this Mitsunobu inversion reaction. Sulfonate esters can also be prepared under Mitsunobu conditions. Use of zinc tosylate in place of the carboxylic acid gives a tosylate of inverted configuration ... 

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