p-Toluenesulfonic acid monohydrate → p-Toluenesulfonic acid

A reduction reaction was conducted in the same scale as that described in Example 1. An isopropyl alcohol/water solution (20 ml/5 ml) containing 20 g of reduced iron and 1 g of ammonium chloride was heated under refluxing, in advance. To this solution was added, dropwise, a solution obtained by dissolving 20 g of 5-tert-butyl-2-(2-ethylhexylthio)nitrobenzene in isopropyl alcohol (20 ml), over one hour or more. After the addition was finished, the mixture was subjected to after-reaction under refluxing for 1 hour. The reaction solution was cooled to 40° C. and subjected to filtration using celite, followed by washing with 20 ml of toluene. However, filterability when filtering the iron residue was low, bringing about difficult operations. 50 ml of water was added to the filtrate, to carry out phase separation, and the separated phase was washed with 40 ml of an aqueous 0.45 mass % dilute hydrochloric acid solution, to carry out phase separation. 40 ml of water was further added to the solution and the solution was neutralized by adding aqueous sodium bicarbonate, to carry out phase separation, thereby obtaining a toluene solution of Exemplified compound (21). To this solution, 40 ml of toluene was added and then 11.27 g (59.3 mmol, 1.0 eq) of p-toluenesulfonic acid monohydrate was added and dissolved under heating. Then, the solution was cooled for crystallization, thereby obtaining 21.6 g (yield: 75%) of p-toluene sulfonic acid (PTS) salt of Exemplified compound (21).

1. dissolutiondissolved
2. temperatureunder heating
3. temperatureThen, the solution was cooled for crystallization

ORD record

ord-b13d94ac0142422e89a748f396ff97cc

Source dataset

uspto-grants-2007_10

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07282610B2