CH484238A - Process for the preparation of methine dyes - Google Patents

Description

  

  Process for the preparation of methine dyes The present invention relates to a process for the preparation of methine dyes of formulas
EMI0001.0004
    in which the ring B can be substituted by halogen atoms, alkyl or alkoxy groups, the substituents alk. represent lower alkyl groups, identical or different, preferably methyl or ethyl,

   A represents a 6-membered ring comprising 5 carbon atoms and belonging to a mono- or polycyclic system optionally substituted by non-ionizable substituents such as halo- atoms.
EMI0001.0009
    gene, alkyl, alkoxy, cyano, nitro or phenyl groups, and X (D represents a monovalent anion.



  The process according to the invention is characterized in that one condenses, in a medium of anhydrous organic solvent, a 1,3,3-trialkyl-2-methylene indoline of formula (11) with an alkoxy-pyrylium derivative of formula (111) in which alk., A, B and XG have the same meanings as in formulas (1). The new dyes prepared according to the invention are of interest in particular for dyeing fibers and for the photographic industry.



  In dyeing, these dyes have all the properties of cationic dyes and are particularly suitable for coloring fibers based on polymers.
EMI0002.0001
    provides the most diverse acrylic fibers with orange shades of great liveliness that can be rated more than 7 on the Xénotest. This experimental fact was quite unexpected because methine dyes for a long time known and of similar structure but having 2 atoms of heterocyclic nitrogen and no oxygen or at
EMI0002.0004
    The dyes (V) and (VI) provide on acrylic fibers respectively golden yellow and bluish red shades, but the Xenotest rating of which does not exceed 1-2.



  In the following examples the parts are by weight unless otherwise indicated. <I> Example I </I> 13 parts of 2-ethoxybenzopyrylium fluoborate prepared according to H. Meerwein et al. (J. prakt. Ch.

   (2) 147, 283 (1937)) are suspended in 50 parts of dry dioxane. 9 parts of 1,3,3-trimethyl-2-methylene indoline are introduced with stirring over a space of 2 minutes and at room temperature. The temperature rises by itself to 401 ° C. It is stirred for half an hour, brought to 800 ° C. for half an hour and left to cool. An orange crystalline precipitate is deposited which is taken up in 50 parts of acetic acid.

   The mixture is heated until dissolved, 10 parts of concentrated hydrochloric acid are added, then 150 parts of a solution containing 30 parts of sodium chloride. The dye of formula (IV) crystallizes in the appearance of fine orange-red flakes which are filtered, washed with a little salt water at 15 ° C. and dried at 500 C.

      or copolymers of acrylic nitrile. They have a very strong affinity with respect to these fibers and give them very bright shades ranging from yellow to blue-green generally exhibiting excellent unison and often remarkable fastness, in particular to light. Thus, for example, the dye of the opposite formula 2 heterocyclic oxygen atoms and no nitrogen are extremely fugitive to light. The difference is striking when comparing the dye of formula (IV) to its isologue (V) and to pyrylocyanin (VI) from Wizinger (Ange-w. Ch. 1938, p. 895).

      This dye provides on the various fibers based on polymers or copolymers of acrylic nitrile a full-bodied and very bright orange shade, endowed with an extra ordinary fastness to light. Example <I> 2 </I> By operating as in the previous example, but replacing the trimethyl-1,3,3 methylene-2 ifidoline by an equivalent amount of trimethyl-1,3,3 methylene-2 methoxy- 5 indoline a dye is obtained which crystallizes in the form of brilliant red flakes.

   Its aqueous or alcoholic solutions are red. 11 dyes the polymer based fibers of acrylic nitrile a bright red shade having excellent overall fastnesses, especially to light. <I> Example 3 </I> By replacing in Example 1 the 1,3,3-trimethyl-2-methylene indoline by an equivalent amount of 1,3,3-trimethyl-2-methylene-5-chloro-indoline, one obtains a dye that dyes acrylic fibers a bright orange shade.

 

Claims (1)

CLAIM Process for the preparation of methine dyes of formulas EMI0003.0002 in which the ring B may be substituted by halogen atoms, alkyl or alkoxy groups, the substituents alk. represent lower alkyl groups, identical or different, A represents a 6-membered ring comprising 5 carbon atoms and belonging to a mono- or polycyclic system optionally substituted by non-ionizable substituents, and XS represents a monovalent anion, characterized in that one condenses, in an organic solvent medium, a 1,3-trialkyl, 3 methylene-2 indoline of formula (II) with an alkoxy-pyrylium derivative of formula (III) EMI0003.0012 where alk., A, B and X @ have the same meanings as above.