A process for preparing a compound of formula

##STR00001##

including oxidizing the triphenylmethane sulfone of formula (V) with a quinone chosen from 1,4-benzoquinone, 1,2-benzoquinone, a di(C.sub.1-C.sub.4)alkyl-1,4-benzoquinone, a di(C.sub.1-C.sub.4)alkyl-1,2-benzoquinone, a mono(C.sub.1-C.sub.4)alkyl-1,4-benzoquinone and a mono(C.sub.1-C.sub.4)alkyl-1,2-benzoquinone. A crystalline form of patent blue, sodium salt, can be achieved.

A process for preparing a compound of formula

##STR00001##

including oxidizing the triphenylmethane sulfone of formula (V) with a quinone chosen from 1,4-benzoquinone, 1,2-benzoquinone, a di(C.sub.1-C.sub.4)alkyl-1,4-benzoquinone, a di(C.sub.1-C.sub.4)alkyl-1,2-benzoquinone, a mono(C.sub.1-C.sub.4)alkyl-1,4-benzoquinone and a mono(C.sub.1-C.sub.4)alkyl-1,2-benzoquinone. A crystalline form of patent blue, sodium salt, can be achieved.

The present disclosure is directed to provide a vinylsulfonic anhydride which is useful as a synthetic intermediate for synthesis of a fluorinated monomer. It is also directed to efficiently produce the vinylsulfonic anhydride. It is further directed to efficiently produce a fluorinated monomer using the vinylsulfonic anhydride. A vinylsulfonic anhydride of the present disclosure is expressed by the general formula (1). Further, a process for producing a vinylsulfonic anhydride of the present disclosure includes making a vinylsulfonic acid compound represented by the general formula (2) come in contact and be mixed with an anhydridization agent. Further, a process for producing a vinylsulfonyl fluoride of the present disclosure includes a step (b) of making a vinylsulfonic anhydride represented by the general formula (1) come in contact and be mixed with a fluorinating agent to prepare a reaction mixture including a vinylsulfonyl fluoride represented by the general formula (3) and a vinylsulfonic acid compound represented by the general formula (2).

The present disclosure is directed to provide a vinylsulfonic anhydride which is useful as a synthetic intermediate for synthesis of a fluorinated monomer. It is also directed to efficiently produce the vinylsulfonic anhydride. It is further directed to efficiently produce a fluorinated monomer using the vinylsulfonic anhydride. A vinylsulfonic anhydride of the present disclosure is expressed by the general formula (1). Further, a process for producing a vinylsulfonic anhydride of the present disclosure includes making a vinylsulfonic acid compound represented by the general formula (2) come in contact and be mixed with an anhydridization agent. Further, a process for producing a vinylsulfonyl fluoride of the present disclosure includes a step (b) of making a vinylsulfonic anhydride represented by the general formula (1) come in contact and be mixed with a fluorinating agent to prepare a reaction mixture including a vinylsulfonyl fluoride represented by the general formula (3) and a vinylsulfonic acid compound represented by the general formula (2).

There is disclosed a process for producing taurine in a molar yield of at least 80% from alkali isethionate, alkali ditaurinate, or alkali tritaurinate by adding excess ammonia and at least of equal molar amount of an alkali hydroxide to a solution comprised of alkali ditaurinate, alkali tritaurinate, or their mixture and subjecting the solution to an ammonolysis to yield a solution comprised of alkali taurinate.

There is disclosed a process for producing taurine in a molar yield of at least 80% from alkali isethionate, alkali ditaurinate, or alkali tritaurinate by adding excess ammonia and at least of equal molar amount of an alkali hydroxide to a solution comprised of alkali ditaurinate, alkali tritaurinate, or their mixture and subjecting the solution to an ammonolysis to yield a solution comprised of alkali taurinate.

There is disclosed a process for producing taurine in a molar yield of at least 80% from alkali isethionate, alkali ditaurinate, or alkali tritaurinate by adding excess ammonia and at least of equal molar amount of an alkali hydroxide to a solution comprised of alkali ditaurinate, alkali tritaurinate, or their mixture and subjecting the solution to an ammonolysis to yield a solution comprised of alkali taurinate.

A method for simultaneously preparing an iron oxide red pigment and an aromatic amine is provided. In the method, an aromatic nitro compound and ferrous iron are first used to prepare an iron oxide red seed crystal under the action of a catalyst, and then iron powder is used to reduce the aromatic nitro compound and generate iron oxide in situ which grows into iron oxide red with pigment performance on the seed crystal. The method provides a clean and economical way for the reduction of an aromatic nitro compound (especially those in which there are other easily-reduced substituents on an aromatic ring) to prepare an aromatic amine.

A method for simultaneously preparing an iron oxide red pigment and an aromatic amine is provided. In the method, an aromatic nitro compound and ferrous iron are first used to prepare an iron oxide red seed crystal under the action of a catalyst, and then iron powder is used to reduce the aromatic nitro compound and generate iron oxide in situ which grows into iron oxide red with pigment performance on the seed crystal. The method provides a clean and economical way for the reduction of an aromatic nitro compound (especially those in which there are other easily-reduced substituents on an aromatic ring) to prepare an aromatic amine.

A method for simultaneously preparing an iron oxide red pigment and an aromatic amine is provided. In the method, an aromatic nitro compound and ferrous iron are first used to prepare an iron oxide red seed crystal under the action of a catalyst, and then iron powder is used to reduce the aromatic nitro compound and generate iron oxide in situ which grows into iron oxide red with pigment performance on the seed crystal. The method provides a clean and economical way for the reduction of an aromatic nitro compound (especially those in which there are other easily-reduced substituents on an aromatic ring) to prepare an aromatic amine.