P-Toluenesulfonic acid

  • Para-toluenesulfonic
  • 4- methylbenzenesulphonic
  • Toluene-4 -sulfonic acid
  • PTsOH
  • Tosylic
  • PTSA

Colorless or purple, pungent crystals

Fixed

1.24 g · cm -3

140 ° C at 13.3 hPa

10 Pa ( 20 ° C)

~ 0.7

750 g · l - 1 in water

Attention

2570 mg · kg -1 ( LD50, Rat, oral, monohydrate)

Template: Infobox chemical / molecular formula search available

P- toluene sulfonic acid is an organic sulfonic acid. To form a monohydrate, and is an important reagent in organic synthesis. The salts and esters of toluenesulfonic acids are referred to as tosylates, such as, for example, sodium tosylate.

Representation

P-toluenesulfonic acid is a byproduct of the Remsen - Fahlberg process for the preparation of saccharin dar. They produced by sulfonation of toluene. The purification is carried out by crystallization from hydrochloric acid and azeotropic drying.

Properties

In aqueous solutions, p-toluenesulfonic acid is largely dissociated. Their barium or lead salts are, in contrast to those of sulfuric acid, good solubility in water. p- toluenesulfonic acid decomposes in the heat, with sulfur dioxide and others.

Use

P-toluenesulfonic acid is used as an acid catalyst, including for acetalization, esterification or dehydration. Their advantage over sulfuric acid is that it does not act as oxidizing.

Toluenesulfonate as a leaving group

→ see main article tosyl group

In preparative chemistry, the anion of p- toluenesulfonic acid acts as a leaving group in nucleophilic substitutions important. With the acid halide para- toluenesulfonyl chloride ( tosyl chloride ) to hydroxyl groups of a compound can be converted to sulfonic acid. This group is a good leaving group compared to the hydroxy group.

Hazards

P- toluenesulfonic acid always contains some sulfuric acid and therefore has very corrosive to skin, mucous membranes and eyes. Inhalation of dust is a risk of pulmonary edema.

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