P-Toluenesulfonic acid or tosilic acid (TsOH) . It is a strong non-oxidizing organic compound of formula CH 3 C 6 H 4 SO 3 H, white solid, soluble in water, alcohols, and other polar solvents.
Summary
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- 1 Physical properties
- 2 Obtaining
- 3 Applications
- 1 Tosylate esters
- 4 Health Effects
- 5 Measures to take in case of fire
- 6 Sources
Physical properties
TsOH is a strong organic acid, approximately a thousand times stronger than benzoic acid. It is one of the few strong acids that is solid. Also, unlike some strong mineral acids (especially nitric acid, sulfuric acid, and perchloric acid), TsOH, unlike some strong mineral acids (especially nitric acid, sulfuric acid, and perchloric acid), is a non-oxidizing acid. • Melting point: 106 ~ 107 ℃. • Boiling point: 116 ° C • Density: 1.07 • Refractive index: 1.3825-1.3845 • Flash point: 41 ° C • Storage temperature. Flammable area • Form: Solution • Color: Clear colorless to light yellow • Solubility of water: soluble • Flash point: 184 ° C. • Molecular mass: 172.2 g / mol.
Obtaining
This acid is naturally obtained by dehydration and carbonization of cotton fabrics, insoluble in benzene and toluene , thus generating p-cresol. In the industry, the production of methyl acid p-cresol is obtained by using concentrated sulfuric acid in the sulfonation of toluene through p-toluenesulfonic acid. This prepared acid often includes benzene sulfonic acid and sulfuric acid impurities, it can be purified in the re-crystallization of concentrated hydrochloric acid, dry azeotropic acid.
TsOH is prepared on an industrial scale by sulfonation of toluene (toluene is reacted with concentrated sulfuric acid, which is a mixture of H2SO4 and SO3, and sulfonic acid TsOH is formed). The reacting electrophile can be HSO 3 + or SO 3 . C 7 H 8 O 3 S:
CH 3 C 6 H 5 + H 2 SO 4 H (SO 3 ) → p-CH 3 C 6 H 4 SO 3 H (TsOH) + H 2 O
Common impurities include benzenesulfonic acid and sulfuric acid, but these cannot be removed. Hydrates easily.
Applications
P-toluenesulfonic acid is widely used as a catalytic agent in the synthesis of pharmaceuticals, pesticides, polymerization stabilizers. And it is also the catalyst acid that is commonly used in organic synthesis. It is neutralized with sodium hydroxide and then sodium p-toluenesulfonate is obtained and, reacting with phosphorous pentachloride , p-toluenesulfonylchloride is obtained.
The latter is used in the nucleophilic substitution reaction, it is also used as a protecting group for hydroxyl alcohol , it also catalyzes the protection of dihydrofuran in alcohol, the esterification of carboxylic acid and the transesterification reaction, which causes the aldehyde to generate acetal.
Tosylate esters
Tosylates are used as alkylating agents because the tosyl group is an electron-accepting group, making it a good leaving group. The tosyl group is also a protecting group for alcohols and amines , by combining the alcohol or amine with 4-toluenesulfonyl chloride, in an aprotic solvent, often pyridine .
These toluenesulfonate esters can be subjected to nucleophilic attack (by nucleophilic substitution reaction) or elimination. The reduction of tosylate esters gives the hydrocarbon; thus, tosylation followed by reduction allows deoxygenation of alcohols.
Toluenesulfonic acid is used in organic synthesis as a “soluble organic” acid catalyst. Examples of different uses:
- Acetalization of an aldehyde.
- Esterification of carboxylic acids.
- Transesterification of an ester. Other uses:
- p-Toluenesulfonic acid can be converted to p-toluenesulfonic anhydride by heating with phosphorous pentoxide.
- When TsOH is heated with acid and water, a hydrolysis reaction is carried out and tolueneis formed :
CH 3 C 6 H 4 SO 3 H + H 2 O → C 6 H 5 CH 3 + H 2 SO 4
This reaction is general for aryl group derived sulfonic acids, but the rate at which it occurs depends on the acid structure, temperature, and the nature of the acid catalyst. For example, p-TsOH is unaffected by cold concentrated hydrochloric acid, but hydrolyzes when heated to 186 ° C in concentrated phosphoric acid.
In the industry
- Agricultural chemicals
- Catalyst in the manufacture of insulating foam.
- Finishing agents
- Industrial cleaners, metallurgy
- Manufacture of textile dyes, polymer catalysts and coatings.
- Oxidizing / reducing agents
- Additives for paints and additives for coatings not described in other categories
- Active surface agents.
In medicine
- They are used for the creation of medications such as doxycycline
- Widely used in synthetic medicine catalyst
In daily life
- Adhesives and sealants.
- Agricultural products (without pesticides)
- Construction materials not covered elsewhere
- Cleaning and decoration products.
- Textile and leather productsnot included elsewhere
- Paints and coatings
Health Effects
P-Toluenesulfonic acid always contains some sulfuric acid and therefore has a risk of corrosivity to the skin , mucous membranes and eyes . Inhaling it presents a risk of pulmonary edema .
Measures to take in case of fire
In case of fire toxic and irritant gases are released, avoid the flames, to extinguish the flames you can use powder, alcohol resistant foam , sprayed with water, carbon dioxide . In the event of a fire , keep drums and other facilities cool by spraying with water.
