A-Toluenesulfonic acid

Catalysts. The alkanolamines continue to find use as blocked catalysts for textile resins, coatings resins, adhesives, etc. Of particular utifity in curing durable-press textiles is AMP-HCl. Other salts, such as those of the benzoin tosylate or A-toluenesulfonic acid, find utifity in melamine- or urea-based coatings (18) (see Amino resins and plastics). 

Selected entries from Methods in Enzymology [vol, page(s)] Active site titration [by 2-hydroxy-5-nitro-a-toluenesulfonic acid sultone, 19, 6-14 by p-nitrophenyl ester substrates, 19, 14-20 by rapidly reversible, covalently bound substrates, 19, 14-20 by slowly reversible, covalently bound inhibitors, 19, 6-14] assay,... 

SCHEME 2.18 Regioselective isopropylidenation among the three secondary hydroxyls. PTS A, / -toluenesulfonic acid. 

Meanwhile, Mukaiyama et al. [26] developed another similar procedure, by the use of 6-phenyl-2-pyridyl esters, for the synthesis of macrocychc lactones. This method has been used in the synthesis of f - - )-ricinelaidic acid lactone 40) [27]. Thus, as shown in Scheme 13, a mixture of 6-phenyl-2-pyridone, 2-chloro-l-methylpyridinium iodide 28), and triethylamine in dichloromethane was stirred at room temperature for 1 h. To this solution was added a dichloromethane solution of the hydroxy acid 38 and triethylamine under reflux over 6 h to give the activated ester 39 in 99% yield. A dichloromethane solution of 39 was added to a / -toluenesulfonic acid solution in dichloromethane under reflux over 11 h. Acid-induced lactonization led to the macrocycle 40 in 96% yield ... 

Unstable compounds are problematic. A sample purified in the laboratory might have a short shelf-life and poor performance as a standard. Compounds altered by assays are also inconvenient. For example, substituted benzylic alcohols can dehydrate under acidic HPLC conditions, or carboxylic esters can hydrolyze in aqueous mobile phase. An impurity isolated from an active pharmaceutical ingredient as an organic salt of an organic compound poses two problems at once. The analyst must account for both the acid and the base. In the case of a toluenesulfonic acid salt of an aliphatic amine, two different methods of detection might be needed. The toluenesulfonic acid in a reverse-phase HPLC assay can by monitored by UV light, but the aliphatic amine, with no chromophore, must be measured by a different technique. 

Reaction of benzaldehyde with 1 2 octanediol in benzene containing a small amount of p toluenesulfonic acid yields almost equal quantities of two products in a combined yield of 94% Both products have the molecular formula C15H22O2 Suggest reasonable structures for these products... 

Aqueous caprolactam is polymerized alone and in the presence of sebacic acid (S) or hexamethylenediamine (H).t After a 24-hr reaction time, the polymer is isolated and the end groups are analyzed by titrating the carboxyl groups with KOH in benzyl alcohol and the amino groups with p-toluenesulfonic acid in trifluoroethanol. The number of milliequivalents of carboxyl group per mole caprolactam converted to polymer, [A ], and the number of milliequivalents of amino groups per mole caprolactam converted to polymer, [B ], are given below for three different runs ... 

Acylated Corticoids. The corticoid side-chain of (30) was converted iato the cycHc ortho ester (96) by reaction with a lower alkyl ortho ester RC(OR )2 iu benzene solution ia the presence of i ra-toluenesulfonic acid (88). Acid hydrolysis of the product at room temperature led to the formation of the 17-monoesters (97) ia nearly quantitative yield. The 17-monoesters (97) underwent acyl migration to the 21-monoesters (98) on careful heating with. In this way, prednisolone 17a,21-methylorthovalerate was converted quantitatively iato prednisolone 17-valerate, which is a very active antiinflammatory agent (89). The iatermediate ortho esters also are active. Thus, 17a,21-(l -methoxy)-pentyhdenedioxy-l,4-pregnadiene-liP-ol-3,20-dione [(96), R = CH3, R = C Hg] is at least 70 times more potent than prednisolone (89). The above conversions... 

Acetic anhydride acetylates free hydroxyl groups without a catalyst, but esterification is smoother and more complete ia the presence of acids. For example, ia the presence of -toluenesulfonic acid [104-15-4], the heat of reaction for ethanol and acetic anhydride is —60.17 kJ/mol (—14.38 kcal/mol) (13) ... 

H2SnClg 6H20, CISO H + CH OH, CH COOH, as well as ben2ene-, naphthalene-, and -toluenesulfonic acids (44). Zinc chloride is probably the most frequentiy used catalyst. Its activity is sometimes increased by fusion with a small amount of aluminum chloride. In other instances, however, sufficient catalytic effect is obtained with a mineral acid alone. 

Isophorone usually contains 2—5% of the isomer P-isophorone [471-01-2] (3,5,5-trimethyl-3-cyclohexen-l-one). The term a-isophorone is sometimes used ia referring to the a,P-unsaturated ketone, whereas P-isophorone connotes the unconjugated derivative. P-lsophorone (bp 186°C) is lower boiling than isophorone and can be converted to isophorone by distilling at reduced pressure ia the presence of -toluenesulfonic acid (188). Isophorone can be converted to P-isophorone by treatment with adipic acid (189) or H on(Ill) acetylacetoate (190). P-lsophorone can also be prepared from 4-bromoisophorone by reduction with chromous acetate (191). P-lsophorone can be used as an iatermediate ia the synthesis of carotenoids (192). 

Methylphenol. T -Cresol is produced synthetically from toluene. Toluene is sulfonated to yield T i ra-toluenesulfonic acid, which is then converted to 4-methylphenol via the caustic fusion route. A minor amount of 4-methylphenol is also derived from petroleum cmde and coal tars. 4-Methylphenol [106-44-5] is available in 55-gal dmms (208-L) and in bulk quantities as a molten material. 

Refluxing linoleic acid and a primary or secondary alkyl amine with -toluenesulfonic acid in toluene for 8—18 h also yields the substituted amides (32—34). The reaction of methyl esters with primary or secondary amines to make substituted amides is catalyzed with sodium methoxide. Reactions are rapid at 30°C under anhydrous conditions (35). Acid chlorides can also be used. Ai,A/-dibutyloleamide [5831-80-17 has been prepared from oleoyl chloride and dibutyl amine (36). 

Specifically MSA has been found to be more effective than -toluenesulfonic acid and sulfuric acid in preparing dioctyl phthalate (405). A U.S. patent also discloses its use to prepare light-colored fatty esters (406). It is also important as a catalyst to prepare acrylates, methacrylates, adipates, phthalates, trimeUitates, thioglycolates, and other esters. 

Reaction of carboxylate ion with nitrophenyl sulfites gives the carboxylate -nitrophenyl esters. If the -nitrophenyl sulfite is unsymmethcal (02NCgH40S(0)0R, where R is ethyl or phenyl), carboxylate attacks the -nitrophenyl side (69). Some amino acids react with methyl and benzyl sulfites in the presence of -toluenesulfonic acid to give methyl and benzyl esters of the amino acids as -toluenesulfonate salts (70). With alcohols, the conversion of henzil to a monoacetal upon addition of sulfuric acid to the henzil in methanol and dimethyl sulfite proceeds in high yield (71). 

In plasticizer manufacture, eg, of phthalates or sebacates, uskig sulfuric or/ -toluenesulfonic acid catalysts, the temperature (140—150°C) requked for rapid reaction and high conversion may dehydrate or oxidize the alcohol and may yield a dark or foul-smelling product. Neutral titanates do not cause such side reactions. Although a temperature of 200°C is requked, esterifications can easily be forced to over 99% conversion without the formation of odors or... 

The toluenesulfonic acid prepared as an iatermediate ia the preparation ofpara-cmso also has a modest use as a catalyst for various esterifications and condensations. Sodium salts of the toluenesulfonic acids are also used ia surfactant formulations. Annual use of toluene for sulfonation is ca 100,000-150,000 t (30-45 x 10 gal). 

The starting materials of the aldehyde method may be sulfonated. For example. Cl Acid Blue 9 [2650-18-2] Cl Food Blue 2 (Cl 42090), is manufactured by condensing a-(A/-ethylanilino)-y -toluenesulfonic acid with o-sulfobenzaldehyde. The leuco base is oxidized with sodium dichromate to the dye, which is usually isolated as the ammonium salt. In this case, the removal of the excess amine is not necessary. However, this color caimot be used in the food sector because separation of the chromium compounds from the dye is difficult. An alternative method which gives food-grade Cl Acid Blue 9 (14) and dispenses with the use of sodium dichromate employs oxidative electrolysis of the leuco base (49). 

Fig. 5. Direct red dyes, (a) Direct Red 81 described ia text (68) (b) Direct Red 2 (o-toLidiae coupled to two moles of naphthionic acid) (69) (c) Direct Red 23 (aniline coupled to 6,6 -ureylenebis-l-naplitliol-3-sulfonic acid with a second coupling with j aminoacetanilide) (70) and Direct Red 80 (2 mol 6-amino-3,4 -azobenzenedisulfonic acid coupled twice to 6,6 -ureylenebis-l-naphthol-3-sulfonic acid) (73). Direct Red 24 (4-aniino-y -toluenesulfonic acid coupled under acidic conditions to 6,6 -ureylenebis-l-naphthol-3-sulfonic acid followed by an alkaline coupling of o-anisidine) (71) (d) Direct Red 72 (Broenner s acid, ie, 6-artiino-2-naphthalenesulfonic acid coupled under acidic conditions to 6,6 -ureylenebis-l-naphthol-3-sulfonic acid followed by an...

ButylatedPhenols and Cresols. Butylated phenols and cresols, used primarily as oxidation inhibitors and chain terrninators, are manufactured by direct alkylation of the phenol using a wide variety of conditions and acid catalysts, including sulfuric acid, -toluenesulfonic acid, and sulfonic acid ion-exchange resins (110,111). By use of a small amount of catalyst and short residence times, the first-formed, ortho-alkylated products can be made to predominate. Eor the preparation of the 2,6-substituted products, aluminum phenoxides generated in situ from the phenol being alkylated are used as catalyst. Reaction conditions are controlled to minimise formation of the thermodynamically favored 4-substituted products (see Alkylphenols). The most commonly used is -/ fZ-butylphenol [98-54-4] for manufacture of phenoHc resins. The tert-huty group leaves only two rather than three active sites for condensation with formaldehyde and thus modifies the characteristics of the resin. 

The sulfonated resin is a close analogue of -toluenesulfonic acid in terms of stmcture and catalyst performance. In the presence of excess water, the SO H groups are dissociated, and specific acid catalysis takes place in the swelled resin just as it takes place in an aqueous solution. When the catalyst is used with weakly polar reactants or with concentrations of polar reactants that are too low to cause dissociation of the acid groups, general acid catalysis prevails and water is a strong reaction inhibitor (63). 

Esterification. Citric acid is easily esterified with many alcohols under a2eotropic conditions in the presence of a catalyst such as sulfuric acid, / -toluenesulfonic acid, or sulfonic acid-type ion-exchange resin. Alcohols boiling above 150°C esterify citric acid without a catalyst (5—8). 

Catalysts used are usually acids such as sulfuric acid, -toluenesulfonic acid, sulfonic acid ion-exchange resins, and others. The water from the reaction of the citric acid and the alcohol is continuously removed as the azeotrope until no more water is formed. At this point, the reaction is usually complete and the solvent and any excess alcohol is distilled off under mild vacuum. The catalyst is neutralized using carbonate or sodium hydroxide, leaving a cmde product. If a pure product is desired, the ester can be distilled under high vacuum. 

Acrylic Esters. A procedure has been described for preparation of higher esters from methyl acrylate that illustrates the use of an acid catalyst together with the removal of one of the products by azeotropic distillation (112). Another procedure for the preparation of butyl acrylate, secondary alkyl acrylates, and hydroxyalkyl acrylates using -toluenesulfonic acid as a catalyst has been described (113). Alurninumisopropoxide catalyzes the reaction of amino alcohols with methyl acrylate and methyl methacrylate. A review of the synthesis of acryhc esters by transesterification is given in Reference 114 (see... 

When alkoxypyridazine 1-oxides are heated alone or in the presence of p-toluenesulfonic acid the methyl group migrates from the methoxy group to the A-oxide group. In this manner, 4-methoxypyridazine 1-oxide rearranges to l-methoxypyridazin-4(l//)-one, 5-methoxypyridazine 1-oxide to 2-methylpyridazin-5(2//)-one 1-oxide and substituted 3,6-dimethoxypyridazine 1-oxides to l,3-dimethoxypyridazin-6(l//)-ones. 

These observations can be extrapolated to the pyrrole series the 2-amino derivatives are very unstable whereas 3-aminopyrroles appear to be more stable. 3-Amino-l-tritylpyr-role (162) appears to exist in solution exclusively in the imino-A -pyrroline form (163) (83JCS(P1)93). 2-Aminoindole (164) is unusual in that it exists mainly as the 3//-tautomer (165). 4-Alkylaminoindoles (166) undergo an unexpected rearrangement to 4-amino-1-alkylindoles (167) when heated with p-toluenesulfonic acid hydrate (82CC1356). 

A. 2,2-Dimethyl-4-pentenal. In a SOO-mL, one-necked, round-bottomed flask which contains a magnetic stirring bar are placed 108 g (1.5 mol) of 1 sobutyraldehyde (Note 1), 58 g (1.0 mol) of ally alcohol (Note 1), 230 ml of p-cymene (Note 1), and 0.4 g (2 mnol) of p-toluenesulfonic acid nonohydrate... 

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