Abstract: A process for controlling an installation for the production of chemical substances sub-divides the process control into control regions which are controlled in a decentralized manner and in which a closed divisional function is carried out independently in each case. The working condition of a control region is determined by operating types which may be initially given and by a limited number of discrete operating values. The process parameters determining the control region condition are allocated to each operating value in one formulation. These parameters are adjusted by means of suitable devices. In the event of deviations of a parameter, the other formulation parameters are not adapted, but the procedure is interrupted if the permissible parameter limits are exceeded. Increases in the operating values are only permissible from a quasi-stationary working condition which is characterized by a normal signal formed from the process measurement values.

Abstract: A process for the preparation of 4-amino-3-methyl-phenol from 4-nitroso-3-methyl-phenol, which comprises contacting said 4-nitroso-3-methyl-phenol with iron in an acid aqueous medium at a temperature of 20.degree. to 100.degree. C. said medium having pH in the range from 2 to 6.5.

Abstract: A process for the preparation of 1-amino-2-ethoxy-naphthalene-6-sulphonic acid from 2-hydroxy-naphthalene-6-sulphonic acid which comprises:A. contacting 2-hydroxy-naphthalene-6-sulphonic acid with at least an equimolar amount of an alkali metal nitrite in aqueous solution or suspension in the presence of hydrochloric acid, solution or suspension having a pH in the range of 2 to 5 and being at a temperature of 0.degree. to 20.degree. C.;B. reducing the reaction product of step A in an aqueous suspension by contacting the same with excess iron in the presence of at least an equivalent amount of iron-II ions, relative to the reaction product obtained according to step A, in the presence of a mineral acid at a temperature from 50.degree. to 120.degree. C., and treating the thus-obtained reaction mixture with aqueous alkali metal hydroxide in the presence of iron oxide;C.