DE1089900B - Process for the production of metallizable azo dyes - Google Patents

Description

The invention relates to a process for the production of metallizable azo dyes, in particular those which are derived from hydroxyl group-containing heterocyclic compounds.

From German patent 538 108 it is known to carry out sulfuric acid ester derivatives of azo dyes Treating ο, ο'-dihydroxyazo dyes with chlorosulfonic acid in the presence of a tertiary base; these can be applied to cellulose fibers and then to the fibers with the formation of metal complex compounds be re-metallized. These sulfuric acid ester derivatives have little stability in the dyebath, and the resulting metal complex compounds have only moderate washfastness.

Furthermore, in the German patent 870 147 and the USA patent 2 034 305 water-soluble 8-oxyquinoline and / or 8-oxyquinoline radicals containing metallizable dyes described. These owe their solubility in water to what is present in the dye molecule Sulphonic acid groups, which are not removed even during the metallization, so that from such The dyeings obtained have only poor washfastness.

It has now been found that metallizable azo dyes which at least once have a group of the following Formula contain:

N = N-

Method of manufacture
metallizable azo dyes

Applicant:

Imperial Chemical Industries Limited,
London

Representative: Dipl.-Ing. A. Bohr, Munich 5,

Dr.-Ing. H. Fincke, Berlin-Lichterfelde, Drakestr. 51,

and Dipl.-Ing. H. Bohr, Munich 5, patent attorneys

Claimed priority:
Great Britain October 30, 1953 and October 22, 1954

Robert Ronald Davies,

Blackley, Manchester (Great Britain),

has been named as the inventor

SO ₃ H

in which the nitrogen atom in ortho division to the OSO ₃ H group forms part of a heterocyclic ring, are valuable as post-metaUisable dyes because they have good stability in the dyebath and excellent affinity for natural and synthetic fibers and the sulfuric acid ester groups are split off during the post-metallization and the resulting dyes have excellent wash fastness.

The dyes are prepared by sulfating compounds which have at least one Group of formula

OH

in which the nitrogen forms part of the heterocyclic ring.

The starting materials used in this process can be, for. B. by coupling diazotized primary

+0 aromatic amines with one of the above group containing, coupling in the p-position to the OH group Make azo component. Such azo components come, for. B. 8-oxyquinoline, 4-oxyacridine, 4-oxybenzthiazole, 8-oxycinnoline, 2-acetylamino-4-oxybenzthiazole, 2-phenyl-4-oxybenzthiazole, 2-benzoylamino-4-oxybenzthiazole, 4-oxy-2-methylbenzoxazole and 7-chloro-8-oxyquinoline are possible.

2-Amino-4-oxybenzthiazole (mp = 144 ° C.) is obtained by splitting off the methyl group from 2-amino-4-methoxybenzthiazole by means of hydrogen bromide, hydrogen iodide or aluminum chloride; the 2-amino-4-methoxybenzothiazole is produced according to the information in "Helvetica Chimica Acta", Vol. 25 (1942), p. 515. the Acetylation of the 2-amino-4-oxybenz-

009 609/345

1 Q89 900

3 4

thiazoles with acetic anhydride gives 2-acetylamine. As mentioned, the dyes according to the invention are

4-oxybenzthiazole. In a similar way one arrives φιτρη characterized in that it at least once a benzoylation of the 2-amino-4-oxybenzthi'azqls to the group of the structural formula
2-Benzoylamino-4-oxybenzthiazole (m.p. = 207 ⁰ C). at
the conversion of 1-Amino-2-methoxybenzql, Benz-5
aljle.h.ycl un4 sulfur among those described in German Patent 51172 for the preparation of 2-phenylbenzothiazole
described conditions one obtains 4-methoxy-

2-p.henyJbenzthiazq |, which be | the spin-off of OSO H

Methyl group by means of hydrogen iodide or aluminum 10 ³

chloride 4-Oxy-2-phenylbenzthiazole (mp = 138 ° C) supplies. contain, in which the nitrogen atom is part of the 4-oxy-2-methylbenzoxazole (m.p. = 144 ° C) can be formed by heterocyclic ring. They are suitable for acetylation yQn 2-Aminq-l, 3-dip _i xyb.enzol with acetic dyeing textile fibers, in particular Cellulosesäureanhydrid and hydrolysis at 2 ° / _o aqueous sodium hydroxide fibers, according to known acidic Nachkupferungsverfahren. getting produced. 15 The SO ₃ H group of the group with the structural formula

Primary aromatic amines which are suitable for diazotization and coupling with the azide components may be mentioned in particular, such as 4,4'-D, jaminodiphenyl, 4,4'-diamino-3,3'-dimethoxydiphenyl, '4, 4'-diaminoazobenzene, 4,4'-diaminobenzanilide, 3 ', 4-diamino- ₂ o

3,4'-dimethoxybenzanilide, 4,4'-diaminodiphenylamine, OSO H

4,4'-diaminodiphenylurea, 3,3'-diaminobenzaniüd, ³

S.S'-Diaminodiphenylurea, 1,5-DiaminonaphthaUn, in which the nitrogen is a part of the heterocyclic 2,6-diaminonaphthalene, 3,6-diaminocarbazole, 1,8-di-ring forms, makes the dye soluble and becomes with chloro-S.ö-diaminocarbazole, 4,4'-diaminodiphenoxyethane, 25 of the acidic post-coppering 'removed, whereby the ge-2,5-bis- (4'-aminophenyl) -l, 3,4-oxadiazole and 4,4'-duped dye as an insoluble metal complex complex-aminodiphenyl sulfone. dung is fixed on the fiber.

As diazotizable primary aromatic amines "may consequently have dje gekupferten colorations other amines. So you can get a 'exceptionally high. Washfastness that' is achieved without monoamines, for example, those of the benzene series, ₃₀ aid of a Farbfmerrnittels,
such as aminobenzene, the naphthalene series, such as 2-amino- A particularly important class of appellants

naphthalene, or amines, the heterocyclic dye is the one produced by sulfation of the heterocyclic dyes Rings contained in the molecule, such as 6-aminoindazole and compound obtained * that is obtained by coupling a 2- (4'-aminophenyl) -6-methylbenzthiazole. tetrazotized primary aromatic amine of the formula

The diazotization of the primary aromatic amine 35 _w ""

and the coupling with the corresponding azo-com- ^{2 2}

components can be carried out in a manner known per se. The in the X means a bridge member, in such a way that the two starting materials can also be produced by process amino groups directly to aromatic nuclei, according to which compounds such as azo dyes are bonded with at least 1 mole of an azo component with one another or with other suitable compounds 40 emerges which the group
coupled, provided that the connections
can be selected so that the ultimately obtained
Starting material the above-mentioned group at least
once contains.

The starting material is sulphated by 45
Treat with a sulfating agent. As SuIfatierungsmittel z. B. sulfuric acid, chlorosulfonic acid and other agents known for this purpose in e.g. B. 8-Oxychinoh'n.

Consideration. As examples of suitable bridge members X are particularly effective

Settlement products of tertiary amines, e.g. B. of pyridine, 50 aromatic nuclei mentioned, which may contain further 5-ethyl-2-methylpyridine or triethylamine, with sulfur substituents, such as the benzene nucleus, trioxide, the addition products of sulfur trioxide to the naphthalene nucleus, the acridine nucleus and the carbazole Amides, e.g. B. Dimethylformamide, diethylformamide, core, bridges of the formula
Dimethylacetamide, diethylacetamide, tetramethyl urine- "^ l-.

fabric, FormylpiperididjAcetylpiperidid.Formylmorphlid, 55 <* "N-Y

Tetramethyledipamide, dimethylbenzamide, di- \ '

methyl urethane, N-methylacetanilide, N-methylphthalimi- in which the two Benzplkerne optionally further

din and Ν, Ν-diethyl-p-toluoisulfonsäureamid, and the substituents can contain and in the Y either

Addition products proved to be obtained by the reaction of the direct bond or a bridging member, e.g. B.

Chlorosulfonic acid with amides, e.g. B. with formamide, 60

Acetamide, urea, dimethylacetamide and formalinide, - NH -, - S -, - SOg -, - N -—- N -, - N = N -,

optionally in the presence of an excess of the '' Q ^

Amine or the amide as a diluent

will. - NH-CO-NH -, - CO NH -, - O-CH ₂ - CH ₂ -O-

A particularly effective _{sulfating agent} is the 65 unc [reaction product of sulfur trioxide with triethylamine, because sulfation with this agent either by fusing it with the one to be sulfated

Connection at 90 to 120 ° C or by converting the ^C \

reacting substances can take place in the aqueous medium. 70 O

1 089 9QQ

means further combinations of a plurality of the above-mentioned bonds, e.g. B. the group

and a system containing a plurality of azo groups.

The aforementioned dyes containing a plurality of azo groups can be prepared in a known manner represent, e.g. B. by using a diazo component as one of the intermediate "products, which is a is a primary aromatic amine with more than one primary amino group, an azo component chooses the more contains as a clutch position, an intermediate clutch component used which has both a coupling position and an amino group or an easy into an amino group, for example by hydrolysis, contains convertible group, or a component selects which contains a nitro group, which subsequently becomes an azo or azoxy group or an amino group " can be reduced and further z. B. can be reacted with phosgene, or finally by Ver-Wend any combination of such intermediates.

The dyes according to the invention are particularly suitable for dyeing cellulose and other fibers and fabrics, e.g. B. polyamide, super polyamide and polyester fibers and / or cellulose acetate rayon. The preferred classes of dyes according to the invention are particularly for dyeing cellulose fibers and Fabrics suitable for the well-known acidic copper plating process.

The dyes according to the invention can, for. B. for dyeing cellulose fibers or from neutral bath for Dyeing of wo] Ie and polyamide fabrics use Find. * Cellulose fibers can be dyed with these dyes from baths, if desired the salts, e.g. B. Contain sodium sulfate and sodium carbonate. Are the colorations with metallizing agents, in particular with copper plating agents, e.g. B. Copper salts, after-treated, result in excellent colorations Fastness to light, washing and perspiration. On the other hand, the dyes can also be applied to cellulose fibers, which have previously been pickled with metalizing agents. Both processes produce washable dyeings, so that a post-treatment with a color dye is superfluous.

The invention is illustrated in the following examples. Refer to the parts specified therein focus on weight quantities.

_. .
.Example 1

2.5 parts of the compound obtained by coupling \ mole of tetrazotized 4,4'-diaminodiphenyl with 2 moles of 8-oxycinnoline are dissolved in 1/2 parts of Ν, Ν-dimethylformamide, and the solution is stirred at 30.degree. Then 12 parts of the addition product of sulfur tripoxide and Ν, Ν-pimethyJformamide are added. Then, the mixture is heated to 5Q ⁰ C and stirred for 90 minutes at this temperature. Then it is poured into a solution of 9.1 parts of sodium carbonate in 180 parts of water, filtered and dried. The dye obtained is soluble in water and, after copper plating from an acid bath on cellulose, gives red dyeings of excellent washfastness and good lightfastness.

τ,. -ίο
^ice P ^ie

2.1 parts of the tetrazotized by coupling of 1 MpI 4,4'-Diamjnp-3,3'-dimethpxydiphenyl with 2 moles of 8-oxyquinoline obtained compound are dissolved in 50 parts of Ν, Ν-dimethylformamide, and the solution is at Stirred at 30 ° C. To this end, 10.2 parts of the addition product of sulfur trioxide and N, N-dimethylformamide are used The mixture is then brought to 50 ° C heated and stirred at this temperature for 180 minutes. Then it becomes 2normal in 10 parts ice and 50 parts Poured in aqueous sodium hydroxide solution and heated the mixture to 90.degree. The filtrate is with water to 200Teüe diluted, heated to 80 ° C and treated with 40 parts of sodium chloride. Then it is cooled to 25 ° C and filtered again. The solid residue is washed and dried. The dye thus obtained is complete water-soluble and gives an orange-brown solution, the cellulose fibers after the normal acidic re-coppering process dyes in ruby red tones, the excellent washfastness and good lightfastness own. The dye also has good buildability.

Example 3

2 parts of that obtained by coupling 1 mole of tetrazotized 4,4'-diaminobenzene with 2 moles of 8-ßxyquinoline Compound with 50 parts of N, N-dimethylformamide mixed and sulfated in the manner described in Example 2. The sulfation product is made according to Example 2 isolated. The dye obtained gives violet tints on cellulose after the copper plating process excellent washfastness and good lightfastness.

Example 4
■

The compound obtained by coupling 1 mole of tetrazotized 4,4'-diaminobenzanilide with 2 moles of 8-hydroxyquinoline the sulfation according to Example 3 produces a dye, the cellulose fibers after the acidic copper plating process dyes in bright orange tints, which have excellent washfastness and good lightfastness.

Example 5

2.5 parts of the compound obtained by coupling 1 Mql tetrazotized 4,4'-diaminobenzanilide with 2 MqI 8-hydroxyquinoline are mixed with 4 parts of the addition product of sulfur trioxide and triethylamine and heated to 110 to 120 ° C for 30 minutes, whereupon the melt in a mixture of 50 parts of 2N sodium carbonate solution and 100 parts of water is poured. "the mixture is then heated to 60 ° C and with 10 parts of sodium chloride was added. After filtration, the ^^ residue with 5 ° / _o sodium salt solution is washed and dried. The dye is the same as the dye obtained in Example 4.

Instead of the method described above, one can use also a suspension of 2.5 parts of the same starting material Silicate in 150 parts of water by adding them, with equivalent amounts of caustic soda and the additive product Treated by sulfur trioxide and triethylamine at 95 ° C until the dye is diluted aqueous sodium carbonate is completely soluble.

Example 6

The following table shows the shades that are obtained with dyes that are sulfated of compounds produced by coupling 1 mole of diamine with 2 moles of a metallizable End component arise.

Chimney end component

Color shade according to

of re-coppering

on cotton

3,4'-diamino-3 ', 4-dimethoxybenzanilide

4 ₎ 4'-diaminodiphenylurea

5-amino-2- (4'-aminophenyl) -6-methylbenzthiazole

3,3'-diaminobenzanilide

1,3-diaminobenzene

3,3'-diaminodiphenylurea

4,4'-diaminodiphenoxyethane

4,4'-diaminodiphenyl sulfone

4,4'-diaminodiphenyl

2,5-bis (4'-aminophenyl) _-1) 3,4-oxadiazole

3,6-diamminoacridone

2,7-diaminofluorene

3,6-diaminocarbazole

S.o-diamino-l.S-dichlorocarbazole

1,5-diaminonaphthalene

2,6-diaminonaphthalene

4,4'-diamino beets

3,3'-dimethoxybenzidine

4,4'-diamino-3,3'-dimethoxydiphenyl

1-amino-2-methoxy-5-methylbenzene

4,4'-diaminodiphenylene sulfone

4,4'-diaminodiphenylamine

1,4-diaminobenzene

4,4'-diaminoazobenzene

S.ö-Diamino ^ .y-diethoxyacridine

3,6-diamino-10-methylacridine

4,4'-diamino-3,3'-dimethoxydiphenylmethane

4,4'-diaminodiphenoxydiphenyl sulfide

4,4'-diaminodiphenyl sulfide

4,4'-diaminodiphenylethane

4,4'-diamino-3'-nitrodiphenyl

4,4'-diamino-3,3'-dimethoxydiphenyl

4,4'-diaminodiphenylurea

3,3'-diaminobenzanilide

4 ₎ 4'-diaminodiphenylureas

2,5-bis (4'-aminophenyl) -1, 3,4-oxadiazole

4,4'-diaminodiphenoxyethane

3,3'-diaminodiphenylurea

4,4'-diaminodiphenoxyethane

4,4'-diaminodiphenylurea

4,4'-diaminodiphenoxyethane

3,3'-diaminodiphenylurea

4,4'-diaminodiphenylurea

8-oxyquinoline like the same like the like like. like. like. like. like. like. like. like. like. like. like. like.

the same

the same

the same

the same

the same

the same

the same

the same

the same

the same

the same

the same

S-oxy-y-chloroquinoline 4-oxybenzothiazole

4-oxy-2-acetylaminobenzothiazole desgl.

the same

the same

4-oxy-2-methylbenzthiazole 4-oxy-2-phenylbenzthiazole the same

4-Oxy-2-aminobenzothiazole 4-Oxy-2-benzoylamino-benzothiazole

orange

orange

Red

Yellow-brown

orange

Yellow-brown

orange

Yellow Red

Red

scarlet

Red

Red

Red

Red

Red

Red

Bluish red

Ruby red

violet

Red-violet

violet

Red-brown

Bluish brown

violet

violet

pink

orange

Salmon colored

orange

Yellow Red

Blue ruby red

yellow

yellow

orange

orange

Greenish yellow

Greenish yellow

yellow

Yellow-brown

yellow

yellow

Yellow orange

Example 7

A solution of 4.22 parts of the sodium salt of 2-amino-1-oxybenzenesulfuric acid ester in 200 parts of water is cooled to -5 ° C. 5 parts of 36% hydrochloric acid are added, and the solution is diazotized by adding a solution of 1.38 parts of sodium nitrite in 10 parts of water at 0 to -5 ° C. over the course of 10 minutes. The diazo suspension thus obtained is added under stirring to a solution of 2.2 parts of 1,3-dioxybenzene and 6.8 parts of sodium carbonate in 100 parts of water at 0 ⁰ C and stirred at the same temperature for 30 minutes. By diazotizing a suspension of 3.26 splitter 50 parts of ice and 36 5 parts of 4-amino-4'-acetylaminodiphenyl in a mixture of 50 parts of water, by weight ° / _o hydrochloric acid by addition of 3.5 parts of a 40 ° / ₀ Sodium nitrite solution, a solution is prepared to which a sufficient amount of ammonium hydroxide (D = 0.88) is added to keep it alkaline against brilliant yellow. The mixture is then ^{stirred at 0 to 10 °} C. overnight, whereupon the suspension is filtered and the solid residue is washed with cold water. The solid residue is stirred overnight with 200 parts of a 4 ° / ₀ strength sodium hydroxide solution and the resulting solution is diluted with parts of saturated salt solution. The suspension is filtered and the solid residue with 20 ° / ₀ saline and dried. 5.4 parts of the dry compound are dissolved η sodium hydroxide solution in a mixture of parts of water and 10 parts of 2, there are 2 parts of 40 ° / ₀ solution of sodium nitrite was added and the mixture is added to a mixture of 50 parts of ice and 10 parts of 36 ° / _o hydrochloric acid was added at a temperature below 5 ° C and stirred for 2 hours. The excess nitrous acid is removed by adding sulfamic acid, and the diazo suspension is added to a solution of 1.5 parts of 8-oxyquinoline in a mixture of 50 parts of ß-ethoxyethanol, 50 parts of water, 5 parts of 2 η-sodium hydroxide solution and 40 parts of 2 n-sodium carbonate solution at a temperature below 10 ⁰ C was added. The mixture is stirred at the same temperature overnight and then nitrated and

1 089 90Ö

the solid residue washed with water and dried.

2.5 parts of this solid substance are mixed with 10 parts of the addition product of triethylamine and sulfur trioxide and ^{heated to 115 °} C. for 30 minutes, whereupon the mixture is added to a mixture of 200 parts of water and 20 parts of 2N sodium carbonate solution. 40 parts of sodium chloride was added, then 30 minutes at 20 to 25 ⁰ C is stirred, followed by filtering off the suspension and the solid residue washed 10 ° / ₀ saline with 20 parts and dried.

The dye is water-soluble and gives reddish-brown colorations to cellulose fibers during acidic copper plating of good light and wash fastness.

Example 8

A suspension of 1.95 parts of 4-aminostilbene in a mixture of 50 parts of water and 5 parts of 36 ° / _o hydrochloric acid is added with stirring at 0 to 5 ⁰ C by the addition of 20 parts of n / 2-Natriumhitritlösung in the course of 10 ao Diazotized minutes, the stirring is continued at 0 to 5 ⁰ C for 1 hour. The diazo solution thus obtained is added at a temperature below 10 ⁰ C to a solution of 1.8 parts of 4,4'-dioxy-2,2'-benzthiazolylharnstoff in a mixture of 50 parts /? - ethoxyethanol, 50 parts of water and 5 Share 2 η sodium hydroxide solution together with a sufficient amount of 2 N sodium carbonate solution to keep the whole thing alkaline to brilliant yellow. The mixture is then stirred at 0 to 10 ^° C. overnight, then filtered, and the solid residue is washed with water and dried. 2.68 parts of the dried residue are heated to 115 ° C. for 1 hour with 10 parts of the addition product of triethylamine and sulfur trioxide; the mixture is then added to 100 parts of water containing 40 parts of 2N sodium carbonate solution. The solution thus obtained is distilled with steam, to drive off the triethylamine, and filtered at 9O ⁰ C. The filtrate is treated with a solution of 25 g NaCl per 100 cc salted out, filtered again and the solid residue with cold 20 ° / ₀ saline and dried. During acidic copper plating, the dye dyes cellulose fibers in greenish-yellow shades of excellent lightfastness and washfastness.

The 4,4'-dioxy-2,2'-benthiazolylurea used in the above example can be represented as follows:

Suspending 8.3 parts of 2-Arnino-4-oxybenzthiazol in a mixture of 300 parts of water and 20 parts of 32 ° / _o aqueous sodium hydroxide solution. In the solution which is alkaline by the addition of holds 32 ° / ₀ sodium hydroxide solution as needed to Clayton Yellow, passing an at 20 to 25 ° C phosgene until a sample contains only traces of amine. The suspension is then heated to 40 to 45 ° C. for 30 minutes, keeping it alkaline against Clayton yellow and finally filtered. The filter residue is washed with dilute hydrochloric acid until it no longer contains any amine and then dried. The compound obtained in this way melts at 282 ^° C.

60 Example 9

3 parts of the compound obtained by coupling 1 mole of diazotized aminobenzene with 1 mole of 8-oxyquinoline are mixed with 18 parts of the addition product of sulfur trioxide and triethylamine. Then is heated to 115 ° C, stirred for ¹ _J2 hour at this temperature and then poured n-sodium carbonate solution in a mixture of 100 parts of water and 50 parts. 2 The solution obtained in this way is brought to a salt content of 5 g per 100 ecm by adding common salt. The solid residue is washed with 20 parts of cold water and dried.

The dye is easily soluble in water and delivers on polyamide or cellulose acetate fibers when acidic Re-coppering orange tints of excellent washfastness and good lightfastness.

Example 10

2 parts of the by coupling of 1 mole of 4-nitrobenzene diazonium salt compound obtained with 1 mole of 8-oxyquinoline is sulfated according to Example 9. The thus obtained Dye is water-soluble and dyes polyamide or cellulose fibers during acid re-coppering in red tints of excellent wash and lightfastness.

Example 11

1.5 parts by coupling 1 mole of 4-diethylaminobenzene diazonium salt compound obtained with 1 mole of 8-oxyquinoline is sulfated according to Example 9.

The dye is water-soluble and yields on polyamide or cellulose fibers during acid re-coppering red shades of excellent wash and lightfastness.

Claims (10)

PATENT CLAIMS: 1. Process for the production of azo dyes, which are free of sulfonic acid groups and contain at least one group of the formula: N = N- O · SO ₃ H in which the nitrogen atom ortho to the O · SO ₃ H group forms part of a heterocyclic ring, characterized in that an azo compound which is free from sulfonic acid groups and at least once a group of the formula is sulfated N = N OH contains, in which the nitrogen atom in the ortho position to the OH group is part of a heterocyclic Ring forms. 2. The method according to claim 1, characterized in that compounds of the formula A-N = N-X-N = N-B sulfated, in which A and B are aromatic radicals, of which at least one is the group OH contains, wherein the azo group in the p-position to 009 609/345 1 089 9ÜO O Η group is bonded to the nitrogen atom part of a heterocyclic ring and X is a bridge member. 3. The method according to claim 2, characterized in that X is a radical of the formula -Y- < means in which Y either the direct bond or - NH -, - NH - CO - NH -, -N = N -, N -, - NH - CO -, - S -, - SO ₂ -, ^x o ^/ -OCH ₂ CH ₂ O- or N- -N means and in which one or both benzene nuclei up can optionally contain further substituents. 4. The method according to claim 1 to 3, characterized in that a compound of the formula AN = NMN = NQN = NB * ⁵ sulfated, in which A and B have the above meaning ¹ and in which M and Q are aromatic radicals which may optionally contain further substituents. 12th 5. The method according to claim 4, characterized in that M and or or Q contain such substituents in the ortho position to the azo bonds that a metallizable system or systems are formed. 6. The method according to claim 1 to 5, characterized in that that the sulfating agent is the reaction product of a tertiary amine with sulfur trioxide used. 7. The method according to claim 6, characterized in that the tertiary amine is pyridine, 5-ethyl-2-methylpyridine or triethylamine is used. 8. The method according to .Anspruch 1 to 5, characterized in that that the sulfating agent is the reaction product of an amide with sulfur trioxide used. 9. The method according to claim 8, characterized in that that dimethylformamide is used as the amide. ■ · 10. The method according to claim 6 to 9, characterized in that there is an excess of the tertiary Amine or des, amide is used as a diluent. , Considered publications:
German Patent Nos. 538 180,590190,844 768, 321, 870 147, 882 738, 889 488;
U.S. Patent No. 2,034,305. When the application was announced, a coloring table with an explanation was displayed. © 009 609/345 9.60