19  US 7,144,993 B2  20  COMPARISON EXAMPLE 5 (DE-A-95 86 47)  COMPARISON EXAMPLE 4 (DE-A-1278039)  wherein R 5 , R 6  and R 8  are each independently of the  others a hydrogen atom, a nitro group, a sulfa group, a  halogen atom, a pseudohalogen, a group COOR 1  or  in an aprotic organic solvent in the presence of a catalyti› cally active amount of a strong acid (catalyst) or of an agent  that liberates a strong acid or of an ammonium salt of a  strong acid, it also being possible for the catalyst to be part  of the starting material/product, into a compound of formula  I,  8.4 g of diketene are stirred with 15 g of toluene, and 7 .2  g of 4-chloro-1,3-diaminobenzene are added at such a rate  that the heat of reaction causes the temperature to rise to  60-70°  C. After being stirred for one hour at 60-70°  C., the  mixture is cooled to 15°  C. 50 g of water and 10 g of HCI  (37%) are introduced into the black oil and the mixture is  then distilled until a boiling temperature of 95-100°  C. is  reached. That temperature is maintained for 2 h. After about  one hour, the black solution changes into a suspension. The  greyish-green suspension is then cooled to 15°  C., stirred for  30 minutes and filtered. The greyish-green filter cake is  introduced into 50 g of water; 5 g of sodium acetate are  added and the mixture is boiled for one hour. The mixture is  then cooled to room temperature and the suspension is  filtered. The grey product is washed neutral with 200 g of  cold water and dried at 60°  C. in vacuo. 6 g (yield: 58%,  isomeric ratio of 4-methyl-6-chloro-7-aminoquinolone to  4-methyl-5-amino-6-chloroquinolone=about 53:47) of a  grey solid having a melting point of 290°  C. are obtained.  which comprises converting a compound of the formula  (II)  (I)  1.  A process for the preparation of a compound of the  formula  What is claimed is:  18.8 g (0.1 mo!) of 4-sulfo-1,3-phenylenediamine are  suspended in 150 ml of water and the suspension is heated  to 35°  C. 9.3 g (0.11 mo!) of diketene are added to the grey  suspension in the course of 60 minutes at 35--40°  C. The  mixture is heated to 92°  C. in the course of 30 min; 4 g of  SN  HCI are then added to the yellowish-green suspension  and the mixture is boiled under reflux for a further 2 h. A  further 33 g of  SN  HCI are then added. The suspension is  cooled to 22°  C., filtered and washed with a total of 150 ml  of cold water In portions. The grey product is dried over› night at 60°  C. in vacuo. 9 g (yield 35%; ratio of 4-methyl- 6-sulfo-7-aminoquinolone:  4-methyl-5-amino-6-sulfoqui› nolone: further, unidentified product=71:21:8) of a beige  solid having a melting point of 288°  C. are obtained.  17 .2 g of 95% 4-chloro-1,3-diaminobenzene are dissolved  in 250 g of warm water. With stirring, 9.3 g of diketene are  added dropwise in the course of 1 hour at 90---95° C., the  aceto-acetyl compound being precipitated partially in oily  form. After the addition of 27 g of 2N sulfuric acid, the  mixture is heated at 95°  C. for 2 h. The oily acetoacetyl  compound rapidly changes into a fine, crystalline, dark› brown precipitate. The hot reaction mixture is neutralised  with 30 ml of 2N Na OH and stirred for a further 30 minutes.  The hot reaction mixture is filtered and washed neutral with  100 ml of cold water in portions. The deep-brown product is  dried at 60°  C. in vacuo. 18 g (yield: 78%, ratio of 4-methyl- 6-chloro-7-aminoquinolone:  4-methyl-5-amino-6-chloro- quinolone: further, unidentified product=about 86: 13: 1) of a  dark-brown solid having a melting point of 345°  C. are  obtained.  -continued  1. diketene, water,  1 h, 35-40°  C.  2. 5NHC1,  2 h, 95-100°  C.  1.  toluene, diketene, 1 h, 60-70°  C.  2. HCl (37%), H2O, 2 h, 95-100°  C.  0, 