Toluene-p-sulfonic acid

A solution of trifluoroacetic acid in toluene was found to be advantageous for cydization of pyruvate hydrazoncs having nitro substituents[4]. p-Toluene-sulfonic acid or Amberlyst-15 in toluene has also been found to give excellent results in preparation of indole-2-carboxylale esters from pyruvate hydra-zoiies[5,6J. Acidic zeolite catalysts have been used with xylene as a solvent to convert phenylhydraziiies and ketones to indoles both in one-flask procedures and in a flow-through reactor[7]. 

Similarly, 5-thiazole alkanoic acids and their salts are obtained from thioamides and /3-halo -y-keto acids (695). Thus thioarylamides condensed with 3-aroyl-3-bromopropionic acid (88) in isopropanolic solution in the presence of Na COs give first 4-hydroxy-2-aryl-A-2-thiazoline-5-acetic acid intermediates (89), which were dehydrated in toluene with catalytic amounts of p-toluene sulfonic acid to 2,4-diaryl-5-thiazole acetic acid (90) (Scheme 39) (657), with R = H or Me Ar = Ph, o-, m- or p-tolyl, o-, m-, or P-CIC6H4, 0-, m-, or p-MeOC(iH4, P-CF3C6H4, a-thienyl, a-naphthyl (657). 

Write a stepwise mechanism for the conversion of p-toluene sulfonic acid to p-cresol under the conditions shown in the preceding equation... 

A. 2-f2-Bmmoetkyl)-l,3-diozane (1), A 2-L, three-necked flask Is equipped with a mechanical stirrer, thermometer, and gas Inlet tube. In the flask are placed 750 ml of dichloromethane, 112 g (2.00 moll of acrolein (Note 1), and 0.10 g of didnnamalacetone Indicator (Note 2) under nitrogen. The yellow solution is cooled to 0-5°C with an Ice bath. Gaseous hydrogen bromide (Note 3) is bubbled Into the solution with stirring until the Indicator becomes deep red (Note 4). The Ice bath is removed and 1.0 g of p-toluene-sulfonic acid monohydrate and 152.2 g (2.00 mol, 144 mL) of 1,3-propanediol (Note 11 are added. The yellow solution is stirred at room temperature for 8... 

Acid-induced gelling reactions of PF resins can cause severe deterioration of the wood substrate and therefore have lost any importance in the wood adhesives field. Pizzi et al. [85] describe a procedure for the neutralization of acid-hardened PF glue lines by partly using as hardener a mix of p-toluene sulfonic acid with a... 

In a 250 ml Erlenmeyer flask covered with aluminum foil, 14.3 g (0.0381 mole) of 17a-acetoxy-3j5-hydroxypregn-5-en-20-one is mixed with 50 ml of tetra-hydrofuran, 7 ml ca. 0.076 mole) of dihydropyran, and 0.15 g of p-toluene-sulfonic acid monohydrate. The mixture is warmed to 40 + 5° where upon the steroid dissolves rapidly. The mixture is kept for 45 min and 1 ml of tetra-methylguanidine is added to neutralize the catalyst. Water (100 ml) is added and the organic solvent is removed using a rotary vacuum evaporator. The solid is taken up in ether, the solution is washed with water and saturated salt solution, dried over sodium sulfate, and then treated with Darco and filtered. Removal of the solvent followed by drying at 0.2 mm for 1 hr affords 18.4 g (theory is 17.5 g) of solid having an odor of dihydropyran. The infrared spectrum contains no hydroxyl bands and the crude material is not further purified. This compound has not been described in the literature. 

Additional evidence that a dynamic equilibrium exists between an enamine, N-hemiacetal, and aminal has been presented by Marchese (41). It should be noted that no acid catalysts were used in the reactions of aldehydes and amines discussed thus far. The piperidino enamine of 2-ethylhexanal (0.125 mole), morpholine (0.375 mole), and p-toluene-sulfonic acid (1.25 x 10 mole) diluted with benzene to 500 ml were refluxed for 5 hr. At the end of this time the enamine mixture was analyzed by vapor-phase chromatography, which revealed that exchange of the amino residue had occurred in a ratio of eight morpholine to one piperidine. Marchese proposed a scheme [Eqs. (4), (5) and (6)] to account for these... 

In further modifications of these norprogestins, reaction of norethindrone with acetic anhydride in the presence of p-toluene-sulfonic acid, followed by hydrolysis of the first-formed enol acetate, affords norethindrone acetate (41). This in turn affords, on reaction with excess cyclopentanol in the presence of phosphorus pentoxide, the 3-cyclopentyl enol ether (42) the progestational component of Riglovic . Reduction of norethindrone affords the 3,17-diol. The 33-hydroxy compound is the desired product since reactions at 3 do not show nearly the stereoselectivity of those at 17 by virtue of the relative lack of stereo-directing proximate substituents, the formation of the desired isomer is engendered by use of a bulky reducing agent, lithium aluminum-tri-t-butoxide. Acetylation of the 33,173-diol iffords ethynodiol diacetate, one of the most potent oral proves tins (44). ... 

Amino-5-phenylthiomethoxyacetanilide in methanol solution is heated with N,N -bis-meth-oxycarbonyl-isothiourea-S-methyl ether with the addition of a catalytic amount of p-toluene-sulfonic acid for three hours with stirring under reflux. The mixture is then filtered hot and after cooling the febantel product crystallizes out. It is filtered off, rinsed with ether and dried under high vacuum to give the final product, melting at 129°C to 130°C. 

A Preparation of 11 -Methoxy-A -Estradiene-3,17-Dione 0.5 g of A -estradiene-11/3-ol-3,17-dione were dissolved at room temperature in 25 cc of methylene chloride containing 2% of methanol and after 5 mg of p-toluene-sulfonic acid were added, the reaction mixture was agitated for several minutes. Then the reaction mixture was poured into ice water, washed with water until the wash waters were neutral, and distilled to dryness under vacuum. The resulting residue was crystallized from ethyl ether to obtain 0.46 g of 11/3-methoxy-A -estradiene-3,17-dione having a MP of 140°C. 

Dimethyl-6-t-butylphenol Hydrogen chloride Ethylene diamine p-Toluene sulfonic acid... 

Reactive compatibilization of engineering thermoplastic PET with PP through functionalization has been reported by Xanthos et al. [57]. Acrylic acid modified PP was used for compatibilization. Additives such as magnesium acetate and p-toluene sulfonic acid were evaluated as the catalyst for the potential interchange or esterification reaction that could occur in the melt. The blend characterization through scanning electron microscopy, IR spectroscopy, differential scanning calorimetry, and... 

Besides acylation and alkylation reactions, typical carbonyl reactions, such as reduction and substitution, are known. Thus, the oxo group in position 3 of 8 is attacked by sodium cyanide, resulting in the cyanohydrin in 55% yield. Subsequent dehydration with p-toluene-sulfonic acid and acetylation in position 5 gives 1-benzothiepin 12.90... 

Treatment of l-ethylideneamino-3-methylindole 95 with p-toluene sulfonic acid in boiling benzene gave l,2-dihydro[l,2,4]triazino[l,6-a]indole 96 (75CPB2891). The reaction was said to be due to an initial formation of a Diels-Alder-type adduct followed by the liberation of 3-methylindole. Compound % was oxidized either on exposure to air or by the action of chloranil to give 97 (Scheme 24). 

Although low-molar-mass aliphatic polyesters and unsaturated polyesters can be synthesized without added catalyst (see Sections 2.4.1.1.1 and 2.4.2.1), the presence of a catalyst is generally required for the preparation of high-molar-mass polyesters. Strong acids are very efficient polyesterification catalysts but also catalyze a number of side reactions at elevated temperature (>160°C), leading to polymers of inferior quality. Acid catalysts are, therefore, not much used. An exception is the bulk synthesis of hyperbranched polyesters reported in Section 2.4.5.1, which is carried out at moderate temperature (140°C) under vacuum in the presence of p-toluene sulfonic acid catalyst. The use of strongly acidic oil-soluble catalysts has also been reported for the low-temperature synthesis of polyester oligomers in water-in-oil emulsions.216... 

Apart from complex formation involving metal ions (as discussed in Chapter 4), crown ethers have been shown to associate with a variety of both charged and uncharged guest molecules. Typical guests include ammonium salts, the guanidinium ion, diazonium salts, water, alcohols, amines, molecular halogens, substituted hydrazines, p-toluene sulfonic acid, phenols, thiols and nitriles. 

The tartaric acid, 1,8-octanediol and p-toluene sulfonic acid were placed in the flask and the latter flushed with N2. A positive pressure of N2 was then maintained throughout. The mixture was stirred as the temperature was raised to 140 °C to achieve a homogeneous solution the temperature was then allowed to fall to 125 °C and the reaction left to proceed for 3 days. 

Some studies and patents related to the etherification reaction between glycerol and isobutene are available in the literature, which report the production of the ethers with various catalysts, such as zeolites [19], ion-exchange resins [20, 21] and some homogeneous catalysts, e.g., p-toluene sulfonic acid [21, 22] and methane sulfonic acid [22], Recent studies, however, have concentrated on the etherification of glycerol with isobutene on ion-exchange resins [8, 23]. 

The vinyl substituent at C-2 can also act as a Michael acceptor and reaction with certain nucleophiles gives rise to 1,4-addition compounds. For example, p-toluene-sulfonic acid catalyzed addition of thiols to 2-vinyl- or 2-isopropenyl-5(47/)-oxazolones 136 gave, almost exclusively, the Michael adducts 137 that were used... 

---