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Sulfonic acid selective

The reaction of thieno[2,3-Zi]thiophene (142) with Bu"Li affords a lithium intermediate, whose treatment with elemental sulfur and bromopentane produces sulfide 169. Regioselective iV-sulfonation of the latter was successfully carried out by successive reactions with Bu"Li, SO2 and hydroxylamino-O-sulfonic acid. Selective oxidation of sulfide 170 with potassium peroxymonosulfate afforded sulfone 171 (99JHC249). [Pg.151]

Even ia 1960 a catalytic route was considered the answer to the pollution problem and the by-product sulfate, but nearly ten years elapsed before a process was developed that could be used commercially. Some of the eadier attempts iacluded hydrolysis of acrylonitrile on a sulfonic acid ion-exchange resia (69). Manganese dioxide showed some catalytic activity (70), and copper ions present ia two different valence states were described as catalyticaHy active (71), but copper metal by itself was not active. A variety of catalysts, such as Umshibara or I Jllmann copper and nickel, were used for the hydrolysis of aromatic nitriles, but aUphatic nitriles did not react usiag these catalysts (72). Beginning ia 1971 a series of patents were issued to The Dow Chemical Company (73) describiag the use of copper metal catalysis. Full-scale production was achieved the same year. A solution of acrylonitrile ia water was passed over a fixed bed of copper catalyst at 85°C, which produced a solution of acrylamide ia water with very high conversions and selectivities to acrylamide. [Pg.135]

Fig. 1. Selected paths to naphthalenesulfonic acids where N = naphthalene, SA = sulfonic acid, and yld = yield. Fig. 1. Selected paths to naphthalenesulfonic acids where N = naphthalene, SA = sulfonic acid, and yld = yield.
Orthoesters. The value of cycHc orthoesters as intermediates for selective acylation of carbohydrates has been demonstrated (73). Treatment of sucrose with trimethylorthoacetate and DMF in the presence of toluene-/)-sulfonic acid followed by acid hydrolysis gave the 6-0-acetylsucrose as the major and the 4-0-acetylsucrose [63648-80-6] as the minor component. The latter compound underwent acetyl migration from C-4 to C-6 when treated with an organic base, such as / fZ-butylamine, in DMF to give sucrose 6-acetate in >90% yield (74). When the kinetic reagent 2,2-dimethoxyethene was used,... [Pg.34]

Sulfonic acids are prone to reduction with iodine [7553-56-2] in the presence of triphenylphosphine [603-35-0] to produce the corresponding iodides. This type of reduction is also facile with alkyl sulfonates (16). Aromatic sulfonic acids may also be reduced electrochemicaHy to give the parent arene. However, sulfonic acids, when reduced with iodine and phosphoms [7723-14-0] produce thiols (qv). Amination of sulfonates has also been reported, in which the carbon—sulfur bond is cleaved (17). Ortho-Hthiation of sulfonic acid lithium salts has proven to be a useful technique for organic syntheses, but has Httie commercial importance. Optically active sulfonates have been used in asymmetric syntheses to selectively O-alkylate alcohols and phenols, typically on a laboratory scale. Aromatic sulfonates are cleaved, ie, desulfonated, by uv radiation to give the parent aromatic compound and a coupling product of the aromatic compound, as shown, where Ar represents an aryl group (18). [Pg.96]

Efforts to raise the alpha-selectivity have been made. Thus nitration of anthraquinone using nitrogen dioxide and ozone has been reported (17). l-Amino-4-bromoanthraquinone-2-sulfonic acid (bromamine acid) [116-81 -4] (8) is the most important intermediate for manufacturing reactive and acid dyes. Bromamine acid is manufactured from l-aminoanthraquinone-2-sulfonic acid [83-62-5] (19) by bromination in aqueous medium (18—20), or in concentrated sulfuric acid (21). l-Aminoanthraquinone-2-sulfonic acid is prepared from l-aminoanthraquinone by sulfonation in an inert, high boiling point organic solvent (22), or in oleum with sodium sulfate (23). [Pg.310]

The main by-products of the Ullmaim condensation are l-aniinoanthraquinone-2-sulfonic acid and l-amino-4-hydroxyanthraquinone-2-sulfonic acid. The choice of copper catalyst affects the selectivity of these by-products. Generally, metal copper powder or copper(I) salt catalyst has a greater reactivity than copper(Il) salts. However, they are likely to yield the reduced product (l-aniinoanthraquinone-2-sulfonic acid). The reaction mechanism has not been estabUshed. It is very difficult to clarify which oxidation state of copper functions as catalyst, since this reaction involves fast redox equiUbria where anthraquinone derivatives and copper compounds are concerned. Some evidence indicates that the catalyst is probably a copper(I) compound (28,29). [Pg.310]

Commercially, sulfonic acid ion-exchange resins are used in fixed-bed reactors to make these tertiary alkyl ethers (14). Since the reaction is very selective to tertiary olefins and also reversible, a two-step procedure is also used to recover commercially pure tertiary olefins from mixed olefin process streams. The corresponding tertiary alkyl ether is produced in the olefin mixture and then easily separated from the unreacted olefins by simple fractionation. The reaction is then reversed in a second step to make a commercially pure tertiary olefin, usually isobutylene or isoamylene. [Pg.426]

Surfactants are prepared which contain carboxylic acid ester or amide chains and terminal acid groups selected from phosphoric acid, carboxymethyl, sulfuric acid, sulfonic acid, and phosphonic acid. These surfactants can be obtained by reaction of phosphoric acid or phosphorus pentoxide with polyhydroxystearic acid or polycaprolactone at 180-190°C under an inert gas. They are useful as polymerization catalysts and as dispersing agents for fuel, diesel, and paraffin oils [69]. [Pg.565]

Sulfonic esters are most frequently prepared by treatment of the corresponding halides with alcohols in the presence of a base. The method is much used for the conversion of alcohols to tosylates, brosylates, and similar sulfonic esters. Both R and R may be alkyl or aryl. The base is often pyridine, which functions as a nucleophilic catalyst, as in the similar alcoholysis of carboxylic acyl halides (10-21). Primary alcohols react the most rapidly, and it is often possible to sulfonate selectively a primary OH group in a molecule that also contains secondary or tertiary OH groups. The reaction with sulfonamides has been much less frequently used and is limited to N,N-disubstituted sulfonamides that is, R" may not be hydrogen. However, within these limits it is a useful reaction. The nucleophile in this case is actually R 0 . However, R" may be hydrogen (as well as alkyl) if the nucleophile is a phenol, so that the product is RS020Ar. Acidic catalysts are used in this case. Sulfonic acids have been converted directly to sulfonates by treatment with triethyl or trimethyl orthoformate HC(OR)3, without catalyst or solvent and with a trialkyl phosphite P(OR)3. ... [Pg.576]

Siailar to sulfonic acids, but yields different selectivity. [Pg.212]

Rhin(bpy)3]3+ and its derivatives are able to reduce selectively NAD+ to 1,4-NADH in aqueous buffer.48-50 It is likely that a rhodium-hydride intermediate, e.g., [Rhni(bpy)2(H20)(H)]2+, acts as a hydride transfer agent in this catalytic process. This system has been coupled internally to the enzymatic reduction of carbonyl compounds using an alcohol dehydrogenase (HLADH) as an NADH-dependent enzyme (Scheme 4). The [Rhin(bpy)3]3+ derivative containing 2,2 -bipyridine-5-sulfonic acid as ligand gave the best results in terms of turnover number (46 turnovers for the metal catalyst, 101 for the cofactor), but was handicapped by slow reaction kinetics, with a maximum of five turnovers per day.50... [Pg.477]

With XA1PcS3, selective photonecrosis of colonic tumors induced with dimethylhydrazine was observed with low drug doses (0.5 mg kg-1), but selectivity over normal tissue disappeared at 5 mg kg-1.329 The use of this material (in the form of PHOTOSENS as a mixture of di- and tri-sulfonic acids (7)) in extensive clinical treatments in Moscow has been referred to in Section 9.22.4. [Pg.989]

Ozgen M, Reese RN, Tulio AZ Jr., Scheerens JC and Miller AR. 2006. Modified 2,2-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) method to measure antioxidant capacity of selected small fruits and comparison to ferric reducing antioxidant power (FRAP) and 2,2 -diphenyl-l-picrylhydrazyl (DPPJf) methods. J Agric Food Chem 54(4) 1151-1157. [Pg.302]


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See also in sourсe #XX -- [ Pg.12 , Pg.43 ]




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