Organic compounds -- part of the class 532-570 series – Organic compounds – Heterocyclic carbon compounds containing a hetero ring...
Patent
1995-01-20
1997-10-07
Shah, Mukund J.
Organic compounds -- part of the class 532-570 series
Organic compounds
Heterocyclic carbon compounds containing a hetero ring...
C09B 4704
Patent
active
056750021
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a novel process for purifying hydrophobic solids to form granules in the presence of water. Generally, chemical compounds are obtained in their synthesis in a form which necessitates further purification. For example, in the case of coloring agents such as pigments it is necessary for coloristic as well as toxicological reasons to carry out a purification of the crude products in order that organic impurities such as by-products and unconverted starting compounds but also inorganic impurities such as metal salts, which are used as catalysts or in the case of metal-containing pigments such as copper phthalocyanines as starting materials, may be removed. In addition, the crude pigments generally also require finishing; that is, their crystal form and particle size has to be additionally optimized.
In the generally known purification processes, the crude pigments are treated either with sulfuric acid or with organic solvents which dissolve only the impurities. In both cases the pigments are separated from the resulting suspension by filtration and must afterwards be washed with large amounts of water. The workup of the resulting solvent and water quantities is costly.
To finish the crude pigments, i.e. convert them into a granular form, various processes are known in which the pigments are in each case treated with a two-phase mixture of water and a water-immiscible organic liquid. For instance, DE-A-36 36 428 describes a process using aliphatic C.sub.3 -C.sub.9 -ketones as organic liquid. DE-A-24 12 369 and DE-A-25 20 528 disclose for this purpose the use of-water-immiscible alcohols, aliphatic and aromatic hydrocarbons, halogenated aliphatic hydrocarbons and esters. The two-phase systems may also have added to them further additives which are solid at room temperature, for example carrier substances such as resins (DE-A-25 40 335 and DE-A-26 00 211).
However, the known processes have the disadvantage that the purification and finishing/granule formation are carried out separately and that the purification additionally produces large amounts of liquids to be worked up.
It is an object of the present invention to remedy these defects and to provide a technically simple, economical process for the simultaneous purification and granule formation of the pigments.
We have found that this object is achieved by a novel process for purifying hydrophobic solids to form granules in the presence of water, which comprises treating the solids, if desired more than once, with one or more different two-phase systems comprising consists essentially of one or more water-immiscible or partially water-miscible organic liquids, and inorganic acid or an inorganic base, or resulting granules from the aqueous phase.
The purification process of the invention has many potential uses. The solids to be treated should be substantially insoluble not only in the organic liquids used but also in water. A particularly important group of industrial products includes for example pigments, dyes and their intermediates.
Pigments which can be treated according to the invention are essentially crude pigments as synthesized or as obtained from a subsequent activating dry or wet grind, or pigments still containing heavy metal impurities after finishing. Examples of suitable pigment groups are phthalocyanines, isoindolines, perylene pigments, azo pigments and pigments from vat dyes. The pigments are not just purified, but can, given suitable conditions, be at the same time influenced in their crystal structure and their particle size in the desired manner, so that coloristically useful pigments are obtained.
Suitable dyes include for example disperse dyes, solvent dyes, basic dyes in the form of the underlying bases, mordant dyes, vat dyes and metal complex dyes.
Similarly, the intermediates occuring in the synthesis of the pigments and dyes mentioned come into consideration for purification according to the invention. For instance, the trihydroxy compound which in the synthesis of vat dyes is produced in mixture wi
REFERENCES:
patent: 4459233 (1984-07-01), Fabian et al.
patent: 4789739 (1988-12-01), Kranz et al.
BASF - Aktiengesellschaft
Shah Mukund J.
Sripada Pavanaram K.
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