Process for synthesizing sulfonated triaryl methane compounds

1 . A process for preparing a compound of formula (I), the process comprising:

oxidizing triphenylmethane sulfone of formula (V) with a quinone comprising 1,4-benzoquinone, 1,2-benzoquinone, a di(C 1 -C 4 ) alkyl-1,4-benzoquinone, a di(C 1 -C 4 ) alkyl-1,2-benzoquinone, a mono (C 1 -C 4 ) alkyl-1,4-benzoquinone, or a mono (C 1 -C 4 ) alkyl-1,2-benzoquinone:

wherein, in the compound of formula (I)

R1, R2, and R3 are independently —H, —OH, —SO 3 H, or —SO 3 , at least one of R1, R2, and R3 is —SO 3 H or —SO 3 ,

R4 and R5 are independently a C 1 -C 8 alkyl, a C 1 -C 8 alkenyl, a phenyl, or a benzyl, wherein two groups R4 and R5 borne by the same nitrogen atom optionally together form a ring including the nitrogen atom,

Y is an organic or inorganic cation, which is pharmaceutically acceptable, and

t is 0, ½, or 1.

2 . The process of claim 1 , wherein the quinone is 1,4-benzoquinone.

3 . The process of claim 1 , wherein the oxidizing is performed in an apolar protic solvent.

4 . The process of claim 1 , wherein the oxidizing is performed at a temperature in a range of from 40 to 130° C.

5 . The process of claim 1 , further comprising, on conclusion of the oxidizing:

separating the compound of formula (I) from a reaction medium by precipitation.

6 . The process of claim 1 , further comprising:

converting the compound of formula (I), wherein t is 0, into a salt of formula (I), wherein t is ½ or 1.

7 . The process of claim 1 , wherein the compound of formula (I) has a formula (IA)

8 . The process of claim 7 , further comprising:

(a) condensing a benzaldehyde compound of formula (IIA) with a dialkylaniline of formula (III) to give a triphenylmethane of formula (IVA)

b) treating the triphenylmethane of formula (IVA) with sulfuric acid to form a triphenylmethane sulfone of formula (VA)

9 . The process of claim 1 , wherein the compound of formula (I) is of formula (VI) or (VII):

10 . The process of claim 1 , wherein the compound of formula (I) has formula (IB):

11 . The process of claim 10 , wherein the compound of formula (I) has formula (VIII):

12 . The process of claim 1 , wherein the quinone comprises 1,4-benzoquinone.

13 . The process of claim 1 , wherein the quinone comprises 1,4-benzoquinone, and

wherein the oxidizing is performed in an apolar protic solvent.

14 . The process of claim 1 , wherein the oxidizing is performed at a temperature in a range of from 60 to 120° C.

15 . The process of claim 1 , wherein the oxidizing is performed at a temperature in a range of from 70 to 110° C.