Para-toluene sulfonic acid

Scheme 4 outlines the synthesis of key intermediate 7 in its correct absolute stereochemical form from readily available (S)-(-)-malic acid (15). Simultaneous protection of the contiguous carboxyl and secondary hydroxyl groups in the form of an acetonide proceeds smoothly with 2,2 -dimethoxypropane and para-toluene-sulfonic acid and provides intermediate 26 as a crystalline solid in 75-85 % yield. Chemoselective reduction of the terminal carboxyl group in 26 with borane-tetrahydrofuran complex (B H3 THF) affords a primary hydroxyl group that attacks the proximal carbonyl group, upon acidification, to give a hydroxybutyrolactone. Treat-... 

Experimental Procedure. Morwell brown coal was solubilised by reacting with phenol, in the presence of para toluene sulfonic acid, at 1830C, and the reaction product was then separated into four fractions and analysed according to procedures described elsewhere (lj. The structural characteristics of the four fractions as determined by the present work and confirmed by reference to the literature ( ,3) are summarised in Table I. As these characteristics are influenced to some extent by the presence of chemically combined phenol, the content of this in each fraction is also estimated. 

For the synthesis of carbohydrate-substituted block copolymers, it might be expected that the addition of acid to the polymerization reactions would result in a rate increase. Indeed, the ROMP of saccharide-modified monomers, when conducted in the presence of para-toluene sulfonic acid under emulsion conditions, successfully yielded block copolymers [52]. A key to the success of these reactions was the isolation of the initiated species, which resulted in its separation from the dissociated phosphine. The initiated ruthenium complex was isolated by starting the polymerization in acidic organic solution, from which the reactive species precipitated. The solvent was removed, and the reactive species was washed with additional degassed solvent. The polymerization was completed under emulsion conditions (in water and DTAB), and additional blocks were generated by the sequential addition of the different monomers. This method of polymerization was successful for both the mannose/galactose polymer and for the mannose polymer with the intervening diol sequence (Fig. 16A,B). 

Prior to imide formation, the imide-aryl ether ketimine copolymers were converted to the imide-aryl ether ketone analogue by hydrolysis of the ketimine moiety with para-toluene sulfonic acid hydrate (PTS) according to a literature procedure [51,52,57-59]. The copolymers were dissolved in NMP and heated to 50 °C and subjected to excess PTS for 8 h. The reaction mixtures were isolated in excess water and then rinsed with methanol and dried in a vacuum oven to afford the amic ester-aryl ether ether ketone copolymer, 2e (Scheme 8.)... 

Alper and coworkers investigated the influence of more bulky bases (2,2 -bipyridine, 1,10-phenanthroline, and 6,7-dihydro-5,8-dimethyldibenzo[b,j]-l,10-phenantroline) and para-toluene sulfonic acid (p-TsOH) as proton source (proton functions as a Lewis acid). In the presence of p-TsOH a molecular weight up to 10,000 g/mol was reported. This could be slightly increased by the use of benzylbromide instead of p-TsOH, forming PhCH2COCo(CO)4 as catalyst in situ. In this case, a molecular weight comparable to that found in Rieger s work was achieved, but the polymers remain atactic [69]. 

The carbonyl compound (10 mmol) was introduced in the reactor of a Synthe-wave 402 single mode apparatus followed by the acidic catalyst, para-toluene sulfonic acid (PTSA) 10% or montmorillonite clay KSF 1 g (10 mmol) and the reagent (methyl or ethyl orthoformate, 2 equiv.). After irradiation, the product is filtered or washed by a solution of NaHC03 to remove the catalyst and the product is purified by distillation or recrystallization. 

When using propanols for esterification, the alcohol and water form azeotropes making necessary secondary recovery and recycling of alcohol. An industrial process that is conducted in this way makes use of homogeneous catalyst (para-toluene sulfonic acid) lost after reaction [5]. A more efficient solution can found by employing an entrainer for breaking the azeotrope water/alcohol and superacid solid catalyst. Besides, the entrainer has a beneficial effect on the reaction rate, by increasing the amount of alcohol recycled to the reaction space [3]. 

Direct sulfonation of toluene with concentrated sulfuric acid gives a mixture of ortho and para sulfonic acids from which about 40% of toluene para sulfonic acid can be isolated as the sodium salt. The free acid is important as a convenient solid acid, useful when a strong acid is needed to catalyse a reaction. Being much more easily handled than oily and corrosive sulfuric acid or syrupy phosphoric acid, it is useful for acetal formation (Chapter 14) and eliminations by the El mechanism on alcohols (Chapter 19). It is usually called tosic add, TsOH, or PTSA (para toluene sulfonic acid). 

Para-toluene sulfonic acid (pTSA) can be separated from a mixture of toluene sulfonic acids by crystallization and centrifuging. 

Para-toluene sulfonic acid is a versatile catalyst being as effective as sulfuric acid. In fact being solid it is less likely to affect the reactants in a process and is sometimes preferred to sulfuric acid. 

In other words ortho- and para-toluene sulphonyl chlorides are formed, which on high temperature hydrolysis produces ortho- and para-toluene sulfonic acids. This mixture on neutralization, caustic fusion, and acidification produces a mixture of ortho- and para-cresols. The resultant product contains approximately 85% p-cresol and 15% o-cresol from which pure para-cresol (99%- -) and pure ortho-cresol (99%-h) can easily be obtained. 

Para Toluene Sulfonic Acid. [Boliden Intertrade] Catalyst, organic intermediate, hydrotrope. 

Materials. The carboxylic acids used were analytical grade acetic acid (99.9%, Carlo Erba, France), sulfuric acid (98%, Prolabo, France), andheptanoic acid (98%, Fluka, France). Fatty acids were produced from HOSME on a pilot scale (1 kg) by saponification and acid splitting. Fatty acid composition is reported in Table 1. The alcohols were analytical grade ethanol (99.8%, Carlo Erba, France), heptanol (99%, Fluka, France), octanol (99%, Fluka, France). Para-toluene sulfonic acid (PTSA), zinc chloride, and methanol were also analytical grade. Butylamine (98%) was provided by Fluka. 

I ilot-scale production (1 kg), para-toluene sulfonic acid 0.5%, 100°C, 17 h, 1 bar. 

Sanderson (1988) produced PPF by a U ansesterification of diethyl fumarate and propylene glycol with a para-toluene sulfonic acid catalyst (Ripiire 2). The two components were combined and slowly heated to a temperature of 250°C over a five hour period. This mixture was cooled to 100°C and placed under a vacuum of 1 mm Hg to remove any remaining volatile components. Still under vacuum, the reaction... 

The intramolecular coupling between the hydroxyl functions of the HOVE units of block A and the pendant vinyl ether functions of block C was then achieved in presence of pyridinium para-toluene sulfonic acid salt (PTSA) as catalyst. The reaction between hydroxyl functions and vinyl ether groups yield the rapid formation of acetal links between the A and C sequences, as described in Scheme 21.7. 

The poly(alkylene tartrates) are synthesized by melt polymerization. Both Bronsted-Lowry acids and Lewis acids can be used to catalyze the reaction. Bitritto used para-toluene sulfonic acid (pTSA). The resulting polymers were, in general, colored brown, indicating that the alpha-hydroxyls of the tartaric acid may have been oxidized. When tin chloride was used as the catalyst a lightly colored polymer was formed, indicating that some oxidation probably occurred. Upon purification of the product however, the yellow color was removed. It appears that more favorable reaction conditions exist when tin chloride is used as the catalyst and thus it has become the catalyst of choice for future syntheses. 

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