2-amino-6-chloro-4-nitro-phenol derivatives, process to their pr

Details 2-amino-6-chloro-4-nitro-phenol derivatives, process to their pr 2-amino-6-chloro-4-nitro-phenol derivatives, process to their pr

1990-08-17

1991-11-26

Lieberman, Paul

Bleaching and dyeing; fluid treatment and chemical modification

Dyeing involving animal-derived natural fiber material ,...

Hair dyeing

8406, 8414, 8416, 564440, 564441, A61K 713, C07C32100, C07C21100

Patent

active

050679660

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

The subject matter of the invention concerns new 2-amino-6-chloro-4-nitrophenol derivatives, processes for their production and hair dye compositions which contain 2-amino-6-chloro-4-nitrophenol derivatives as direct dyeing nitro dyes.
Nitro dyes have attained a substantial importance for hair dyeing. Hair dye compositions which are capable of dyeing in natural or fashionable shades without the addition of oxidizing agents can be produced by means of combining different nitro dyes. The nitro dyes are also important components of oxidizing hair dye compositions in which they are utilized for rounding off the dyeing results and for producing fashionable effects.
Such nitro dyes which can impart an intensive red coloring to the hair are required in particular for producing fashionable red effects.
For a long time, 2-nitro-p-phenylenediamine was used for this purpose, but it has been objected to recently on toxicological grounds.
A whole series of demands have been made on dyes to be used for dyeing human hair. They must be unobjectionable in both toxicological and dermatological respects.
Moreover, a good fastness to light, acid and friction is required for the hair dye. Its use in oxidizing hair dye compositions further requires that the nitro dyes be stable against hydrogen peroxide in ammoniacal solution and against antioxidants.
A nitro dye which is suitable as an addition to oxidative hair dye compositions must also dye the hair root with sufficient intensity, the latter being less damaged compared to the hair tips. Meeting this demand is very important for achieving a balanced dyeing result, e.g. in the coupler-developer substance combinations of 4-aminophenol and 2,4-diaminoanisole or 4-amino-3-methylphenol and 2,4-diaminoanisole which are usually frequently used. In a dye test, the more damaged hair tips are dyed a deeper red than the less damaged hair roots with such a combination. In order to balance this dyeing behavior, nitro dyes which preferably dye the hair root must be added to the hair dye compositions.
An example of such a nitro dye is 2-nitro-1,4-diaminobenzene. The dye colors the hair an intense neutral red. But it has the disadvantage that it is not favorably stable in storage, particularly in the presence of reducing agents such as ascorbic acid. Moreover, 2-nitro-1,4-diaminobenzene is mutagenic.


SUMMARY OF THE INVENTION

Therefore, it is an object of the present invention to provide a direct dyeing hair dye which is capable of dyeing the hair an intense, pure red shade and which can be better tolerated in physiological respects and is also more advantageous with respect to coloring than the hair dyes known from the prior art.
According to our invention this object is attained in an outstanding manner by a 2-amino-6-chloro-4-nitrophenol derivative of the general formula (I) ##STR2## wherein the radical R designates a straight-chain or branched alkyl group with 1 to 5 carbon atoms.
Examples of the compounds of formula (I), according to the invention, are 2-chloro-6-methylamino-4-nitrophenol, 2-chloro-6-ethylamino-4-nitrophenol, 2-chloro-4-nitro-6-propylaminophenol, 2-chloro-6-((2'-methylpropyl)amino)-4-nitrophenol and 2-chloro-6-((2',2'-dimethylpropyl)amino)-4-nitrophenol.
The new nitro dyes according to the general formula (I) can be produced e.g. by means of the following processes:
According to a first process, 2-amino-6-chloro-4-nitrophenol is first reacted with a carboxylic acid chloride of the formula R.sup.1 C(O)Cl or a carboxylic acid anhydride of the formula O(C(O)R.sup.1).sub.2, wherein R.sup.1 is hydrogen or a straight-chain or branched alkyl group with 1 to 4 carbon atoms, and the resulting R.sup.1 -substituted N-(3-chloro-2-hydroxy-5-nitrophenyl)carboxylic acid amide is then reduced with sodium borohydride in the presence of boron trifluoride etherate to form the compound of formula (I). The reduction step is preferably carried out at 60 degrees Celsius in tetrahydrofuran as solvent.
According to a second process, 2-amino-6-chloro-4-nitrophenol

REFERENCES:
patent: 2750326 (1956-06-01), Eckardt
patent: 4125601 (1978-11-01), Bugaut
patent: 4575378 (1986-03-01), Seidel et al.

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