Reactive dyes, their preparation and use

Information

  • Patent Grant
  • 4426328
  • Patent Number
    4,426,328
  • Date Filed
    Monday, September 29, 1980
    44 years ago
  • Date Issued
    Tuesday, January 17, 1984
    40 years ago
Abstract
Dyes of the formula ##STR1## in which D is an organic dye radical which contains at least one group conferring solubility in water, R is a halogenoalkyl radical having 1 to 2 C atoms or a halogenoacryl radical and n is an integer from 1 to 4 and each group of the formula ##STR2## is bonded to D via an aromatic carbon atom, are prepared by reacting the corresponding dye compounds of the formula D--H).sub.n with halogenoalkanoylamidoglycolic or halogenoacryloylamidoglycolic acids and are suitable for dyeing cellulose and polyamide materials.
Description

The invention relates to fibre-reactive dyes of the formula ##STR3## in which D is an organic dye radical which contains at least one group conferring solubility in water, R is a halogenoalkyl radical having 1 to 2 C atoms or a halogenoacryl radical and n is an integer from 1 to 4.
The radicals of the formula ##STR4## are each bonded to an aromatic carbon atom of D, in particular to a benzene nucleus.
The radical of an organic dye D in formula (1) can contain further substituents. Examples are: alkyl groups having 1 to 4 carbon atoms, such as methyl, ethyl, propyl, isopropyl and butyl, alkoxy groups having 1 to 4 carbon atoms, such as methoxy, ethoxy, propoxy, isopropoxy and butoxy, aryloxy groups, such as phenoxy or phenoxy substituted by chlorine, bromine, nitro, methyl or methoxy, acylamino groups having 1 to 6 carbon atoms, such as acetylamino, propionylamino and benzoylamino, halogen, such as fluorine, chlorine or bromine, nitro, cyano, trifluoromethyl, sulfamoyl or carbamoyl which are unsubstituted or N-monosubstituted or N,N-disubstituted by alkyl and/or aryl, and ureido, hydroxyl, carboxyl and sulfomethyl.
Preferably, D should contain a phenyl radical, which is unsubstituted or substituted by C.sub.1 -C.sub.4 -alkyl or C.sub.1 -C.sub.4 -alkoxy, since the novel reactive group can be introduced into such a radical particularly well.
The radical D preferably contains sulfo groups as the groups conferring solubility in water.
In particular, D is a dye of the anthraquinone, azo, dioxazine or phthalocyanine series which contains 1 to 3, preferably 1 or 2, sulfo groups.
Dyes of particular interest are the anthraquinone and azo dyes which contain one or 2 groups of the formula (1) and in which the radical R has one of the following meanings: --CH.sub.2 Cl, --CH.sub.2 Br, --CCl.dbd.CH.sub.2, --CHCl--CH.sub.2 Cl or in particular --CHBr--CH.sub.2 Br and --CBr.dbd.CH.sub.2.
Anthraquinone dyes which are of interest are, in particular, those of the formula ##STR5## in which R.sub.1 is hydrogen, cycloalkyl low-molecular alkyl, aralkyl or aryl, Ar is an arylene radical, Z is an .alpha.,.beta.-dichloro- or -dibromo-propionyl radical, an .alpha.-chloro- or .alpha.-bromoacryloyl radical or a chloroacetyl radical, m is 1 or 2 and p is 1 or 2 and in which the ring a can be substituted by hydroxyl or halogen.
In this formula, R.sub.1 is preferably hydrogen or a secondary alkyl radical or a cycloalkyl radical having not more than 9 C atoms, for example 2-methyl-3-butyl, 2-pentyl, 3-pentyl, cyclopentyl, cyclohexyl, cyclohexyl substituted by 1 to 3 methyl groups and in particular isopropyl and 2-butyl.
Ar is preferably a radical of the benzene series, which can be substituted, for example by C.sub.1 -C.sub.4 -alkyl, C.sub.1 -C.sub.4 -alkoxy, C.sub.1 -C.sub.4 -alkylsulfonyl, carboxyl, sulfo, sulfamoyl, N-alkyl- or N-aryl-sulfamoyl or halogen. In particular, however, Ar is a phenylene radical substituted by not more than 3 methyl groups.
The ring a can carry a sulfo group or other substituents, for example halogen, especially chlorine, or hydroxyl.
A further group of anthraquinone dyes which are of particular interest are those of the formula ##STR6## in which A.sub.1 and A.sub.2 are each an unbranched or branched alkylene radical having not more than 5 carbon atoms and Z is an .alpha.,.beta.-dichloro- or -dibromo-propionyl radical, an .alpha.-chloro- or .alpha.-bromo-acryloyl radical or a chloroacetyl radical and in which the ring a' can be substituted by hydroxyl or halogen.
If the ring a' is substituted by hydroxyl groups, these are preferably in positions 5 and 8. Suitable halogen atoms are bromine and in particular chlorine. These are located, in particular, in positions 6 and/or 7 of the anthraquinone ring system.
The radicals A.sub.1 and A.sub.2 can be identical or different. Preferably, A.sub.1 and A.sub.2 are each 1-methylpropylene chains.
In addition to the anthraquinone dyes mentioned, azo dyes are also of interest, especially those of the formula ##STR7## in which D is the radical of a diazo component of the benzene or naphthalene series and K is the radical of a coupling component, preferably the radical of a naphtholsulfonic acid, of an acetoacetanilide, of a pyrazol-5-one or of a naphtho-(1,2-d)-imidazole.
Preferably, D is a radical of the benzene series, which is substituted by C.sub.1 -C.sub.4 -alkyl, in particular methyl.
The radicals K are derived in particular from the following groups of coupling components: naphtholsulfonic acids, for example 2-naphthol-3-, -4-, -5-, -6-, -7- or -8-sulfonic acid or 1-naphthol-3-, -4- or -5-sulfonic acid, acetoacetic acid arylides, especially acetoacetic acid anilides, which can be substituted in the anilide nucleus by chlorine, bromine, sulfo, C.sub.1 -C.sub.4 -alkyl and C.sub.1 -C.sub.4 -alkoxy, for example acetoacetanilide, acetoacetanilide-3- or -4-sulfonic acid, acetoacet-o-chloroanilide, acetoacet-o-toluidide, acetoacet-o-anisidide or acetoacet-m-xylidide, 5-pyrazolones or 5-aminopyrazoles which carry, in the 1-position, a phenyl radical which is unsubstituted or substituted by chlorine, nitro, sulfo, C.sub.1 -C.sub.4 -alkyl or C.sub.1 -C.sub.4 -alkoxy, for example 1-(2'-, 3'- or 4'-sulfophenyl)-3-methyl-pyrazol-5-one, 1-(2'-chloro-5'-sulfophenyl)-3-methyl-pyrazol-5-one, 1-(2',5'-dichloro-4'-sulfophenyl)-3-methyl-pyrazol-5-one, 1-(2'- or 4' -methylphenyl)-3-methyl-pyrazol-5-one or 1-(2'-, 3'- or 4'-methylphenyl)-3-methyl-pyrazol-5-one, and naphtho-(1,2-d)-imidazoles such as have been described in German Offenlegungsschrift No. 2,247,838, for example 1-(2'-chlorophenylamino)-9-hydroxy-2-methyl-1H-naphtho-(1,2-d)-imidazole-7-sulfonic acid, 1-(2',5'-disulfophenylamino)-9-hydroxy-2-methyl-1H-naphtho-(1,2-d)-imidazole-7-sulfonic acid or 1-(2'-chloro-5'-sulfophenylamino)-9-hydroxy-2-methyl-1H-naphtho-(1,2-d)-imidazole-7-sulfonic acid.
The novel dyes are prepared by reacting the corresponding dye compounds
D--H).sub.n ( 6)
in which D and n are as defined in formula (1) and H is a replaceable hydrogen atom bonded to an aromatic carbon atom of D, with a halogenalkanoylamidoglycolic or halogenoacryloylamidoglycolic acid. This reaction takes place under the same conditions as the reaction with N-methylol compounds of aliphatic halogenocarboxylic acid amides or functional derivatives thereof (A. Einhorn, Liebigs Annalen der Chemie, 343, 207 (1905) and 361, 113 (1908)).
Chloroacetamidoglycolic acid has been disclosed in German Offenlegungsschrift No. 2,640,615. The dihalogenopropionamidoglycolic acids and the .alpha.-halogenoacryloylamidoglycolic acids are novel and also constitute a subject of the invention. The dihalogeno compounds are obtained by halogenation of acryloylamidoglycolic acid, and the .alpha.-halogenoacryloyl compounds are obtainable by eliminating hydrogen halide from the dihalogeno compounds by the action of alkali, for example sodium hydroxide solution. Dibromopropionamidoglycolic acid and the .alpha.-bromoacryloylamidoglycolic acid obtainable therefrom by the elimination of HBr are of particular interest.
If desired, this condensation reaction can be followed by yet further reactions, for example the resulting dye can be sulfonated and/or, if the reaction has been carried out using dibromopropionamidoglycolic acid, hydrogen bromide can subsequently be split off by treatment with alkali.
Thus, for example, the compounds of the formula (4) are advantageously prepared by reacting a compound of the formula ##STR8## in which A.sub.1 and A.sub.2 are each an unbranched or branched alkylene radical having not more than 5 carbon atoms and the ring a' is unsubstituted or substituted by hydroxyl or halogen, with 2-equivalents of .alpha.,.beta.-dichloro- or .alpha.,.beta.-dibromo-propionamidoglycolic acid, .alpha.-chloro- or .alpha.-bromoacryloylamidoglycolic acid or chloroacetamidoglycolic acid and subsequently sulfonating the reaction product.
The condensation reaction of the dyes with the acylamidoglycolic acids is carried out in the presence of acid condensing agents or of dehydrating agents which react as acid condensing agents. Agents of this type which can be used are, in particular, concentrated hydrochloric acid, zinc chloride, phosphorus pentoxide, acetic anhydride, phosphoric acid and oleum. The preferred condensing agent is, however, concentrated to anhydrous sulfuric acid, since in most cases this can at the same time serve as the solvent for the reactants. The reaction temperature can vary within wide limits and depends in particular on the condensing agent used. In concentrated sulfuric acid the reaction in most cases already proceeds rapidly and goes to completion at room temperature. In some cases it is necessary to carry out the reaction at elevated temperature, for example at 40.degree. to 80.degree. C. The finished reaction products are precipitated by pouring the solutions or suspensions containing sulfuric acid into ice-water and are isolated in the conventional manner.
Taking into consideration the ready accessibility and with regard to the good dyeing properties of the end products obtainable therefrom, in particular .alpha.,.beta.-dibromopropionamidoglycolic acid is used as the halogenoalkanoylamidoglycolic acid.
The novel dyes are suitable for dyeing and printing very diverse materials, for example those of animal origin, such as leather, silk and in particular wool, and also diverse synthetic fibres, for example made of high molecular weight polyamides and high molecular weight polyurethanes. They are particularly suitable for dyeing from a neutral to acid medium.
The novel dyes are also suitable for dyeing and printing cellulose-containing materials, such as cotton and regenerated cellulose fibres, and for fixing on these materials they are subjected to a heat treatment in the presence of alkali, for example in the presence of sodium (hydrogen) carbonate, sodium hydroxide or trisodium phosphate.
They are particularly suitable for dyeing wool from a weakly acid bath, for example a bath containing acetic acid, in the presence of wetting agents and levelling agents, especially in the presence of polyglycol ether derivatives which on average contain 5 to 10 --CH.sub.2 --CH.sub.2 --O-- groups and are derived from primary monoamines which contain an aliphatic hydrocarbon radical having 15 to 20 carbon atoms.
The dyeings obtained with the novel dyes are distinguished by good fastness to light and fastness to rubbing and excellent wet fastness properties, for example fastness to washing, fastness to water, fastness to perspiration, fastness to damp heat and fastness to milling. They have good solubility in water and a high degree of fixation and give deep, level dyeings.
In the examples which follow parts are by weight, unless indicated otherwise, percentages are by weight and temperatures are in degrees centigrade.





EXAMPLE 1
78 parts of acryloylamidoglycolic acid monohydrate are brominated with 77 parts of bromine in 500 parts of carbon tetrachloride at room temperature. After 20 hours the reaction has gone to completion and the viscous suspension is filtered with suction and the material on the filter is washed with carbon tetrachloride until the wash liquid remains colourless. The material on the suction filter is dried in vacuo at 60.degree. C.; 143 parts of dibromopropionamidoglycolic acid of the formula: ##STR9## are obtained.
A mixture of 16 parts of the dibromopropionamidoglycolic acid thus obtained and 24 parts of the sodium salt of 1-amino-4-mesidinoanthraquinone-2-sulfonic acid of the formula ##STR10## is dissolved in 125 parts of 96% sulfuric acid at 10.degree. to 15.degree.. The reaction mixture is stirred at this temperature for a further 15 hours and is then poured into an ice/water mixture, and the dye which has precipitated is filtered off with suction.
The residue thus obtained is suspended in water and isolated in the form of the sodium salt in a conventional manner. A water-soluble blue dye of the formula: ##STR11## is obtained which dyes wool, preferably in the presence of levelling agents (for example a condensation product of higher aliphatic amines with ethylene oxide) from an acetic acid bath in brilliant blue shades which are fast to wet processing and have good fastness to light.
EXAMPLE 2
The 16 parts of dibromopropionamidoglycolic acid are replaced by 32 parts of the same compound and the procedure according to the instructions of Example 1 is repeated. A bis-reactive dye of the formula: ##STR12## is thus obtained which has very good dyeing properties and excellent wet fastness properties.
EXAMPLE 3
78 parts of acryloylamidoglycolic acid monohydrate are suspended in 500 parts of carbon tetrachloride and 34 parts of chlorine are passed in at room temperature in the course of 4 hours. The suspension is filtered with suction and the material on the filter is washed with carbon tetrachloride. The material on the suction filter is dried in vacuo at 60.degree.; 102 parts of dichloropropionamidoglycolic acid of the formula: ##STR13## are obtained.
A mixture of 12 parts of the dichloropropionamidoglycolic acid thus obtained and 24 parts of the sodium salt of 1-amino-4-mesidinoanthraquinone-2-sulfonic acid are subjected to a condensation reaction using the procedure of Example 1. This yields the reactive dye of the formula: ##STR14## which dyes wool in sky-blue shades which are fast to wet processing.
EXAMPLE 4
76.5 parts of the dye obtainable according to Example 1 are dissolved in 500 parts of water, the solution is cooled to 10.degree. with the addition of ice and 12 parts by volume of 10 N sodium hydroxide solution are added. After stirring for a further 30 minutes at 10.degree.-15.degree., the solution is neutralised by adding about 10 parts by volume of 1 N hydrochloric acid and the dye is precipitated by adding sodium chloride, filtered off and dried in vacuo at 60.degree.-70.degree.. This yields a bromoacryl derivative of the formula: ##STR15## which is readily soluble in water and which dyes wool in sky-blue shades with good fastness properties.
EXAMPLE 5
The above example is repeated except that the 76.5 parts of the dye obtainable according to Example 1 are replaced by 67.5 parts of the corresponding dichloro derivative according to Example 3. An otherwise identical procedure yields the dye of the formula: ##STR16## which has very similar properties.
EXAMPLE 6
A mixture of 9 parts of chloroacetamidoglycolic acid and 24 parts of the sodium salt of 1-amino-4-mesidinoanthraquinone-2-sulfonic acid is dissolved in 125 parts of 96% sulfuric acid at 10.degree.-15.degree.. The reaction mixture is stirred at this temperature for a further 15 hours and is then poured into an ice/water mixture, and the dye which has precipitated is filtered off with suction.
The residue thus obtained is suspended in water and isolated in the form of the sodium salt in a conventional manner. A reactive dye of the formula: ##STR17## is obtained which dyes wool in sky-blue shades which are fast to wet processing and have good fastness to light.
When the procedure of Example 1 is repeated except that the 24 parts of the sodium salt of 1-amino-4-mesidinoanthraquinone-2-sulfonic acid are replaced by equivalent parts of the dyes listed in column II of the table which follows and these are reacted with the parts of dibromopropionamidoglycolic acid indicated in column III, the reactive dyes according to column IV are obtained, the colour shades of these dyes on wool being indicated in column V of the table.
ampleEx-I DyeII IIIParts ofdibromo-propion-amidogly-colic acid ##STR18## Shade on woolV 7 ##STR19## 16 parts ##STR20## neutral blue 8 ##STR21## 32 parts ##STR22## neutral blue 9 ##STR23## 16 parts ##STR24## neutral blue 10 ##STR25## 32 parts ##STR26## greenish-tingedblue 11 ##STR27## 16 parts ##STR28## greenish-tinged blue 12 ##STR29## 16 parts ##STR30## greenish-tinged blue 13 ##STR31## 16 parts ##STR32## red 14 ##STR33## 16 parts ##STR34## bluish-tinged red 15 ##STR35## 16 parts ##STR36## Red 16 ##STR37## 16 parts ##STR38## Orange 17 ##STR39## 16 parts ##STR40## Red 18 ##STR41## 16 parts ##STR42## Red 19 ##STR43## 16 parts ##STR44## Orange 20 ##STR45## 16 parts ##STR46## Black 21 ##STR47## 16 parts ##STR48## Brown 22 ##STR49## 16 parts ##STR50## Orange 23 ##STR51## 16 parts ##STR52## Scarlet 24 ##STR53## 16 parts ##STR54## Red 25 ##STR55## 32 parts ##STR56## Red 26 ##STR57## 16 parts ##STR58## Red 27 ##STR59## 16 parts ##STR60## Claret 28 ##STR61## 16 parts ##STR62## yellow 29 ##STR63## 16 parts ##STR64## yellow 30 ##STR65## 16 parts ##STR66## yellow 31 ##STR67## 16 parts ##STR68## yellow 32 ##STR69## 16 parts ##STR70## yellow 33 ##STR71## 16 parts ##STR72## yellow 34 ##STR73## 16 parts ##STR74## yellow 35 ##STR75## 16 parts ##STR76## yellow 36 ##STR77## 16 parts ##STR78## yellow 37 ##STR79## 16 parts ##STR80## yellow 38 ##STR81## 16 parts ##STR82## yellow 39 ##STR83## 16 parts ##STR84## yellow 40 ##STR85## 16 parts ##STR86## goldenyellow
EXAMPLE 41
A homogeneous mixture of 25 parts of the compound of the formula ##STR87## and 32 parts of dibromopropionamidoglycolic acid (obtained according to Example 1) is introduced into 180 parts of 90% sulfuric acid at a temperature of 5.degree.-10.degree. and the resulting solution is then stirred at the same temperature for 15 hours. For sulfonation, 180 parts of 65% oleum are allowed to run in at 10.degree.-15.degree. and the sulfonation mixture is poured into an ice/water mixture. The bis-reactive dye of the formula: ##STR88## which has precipitated is filtered off with suction and isolated in the form of the sodium salt in the conventional manner.
When the dye is applied to wool, very brilliant blue dyeings are obtained which are distinguished by good fastness to light and very good wet fastness properties.
When the same procedure is repeated except that the anthraquinone compound mentioned initially is replaced by equivalent parts of the dyes listed in column II of the table which follows and these are reacted with the parts of dibromopropionamidoglycolic acid indicated in column III and the reaction products are sulfonated, the reactive dyes according to column IV are obtained; the colour shades of these dyes on wool are indicated in column V of the table.
ExampleI DyeII colic acidamidogly-propion-dibromo-Parts ofIII ##STR89## Shade on woolV 42 ##STR90## 32 parts ##STR91## neutral blue 43 ##STR92## 32 parts ##STR93## neutral blue 44 ##STR94## 32 parts ##STR95## blue 45 ##STR96## 32 parts ##STR97## neutral blue 46 ##STR98## 32 parts ##STR99## neutral blue 47 ##STR100## 32 parts ##STR101## neutral blue 48 ##STR102## 32 parts ##STR103## greenish-tinged blue 49 ##STR104## 32 parts ##STR105## greenish-tinged blue 50 ##STR106## 32 parts ##STR107## greenish-tinged blue 51 ##STR108## 16 parts ##STR109## neutral blue 52 ##STR110## 16 parts ##STR111## violet 53 ##STR112## 16 parts ##STR113## bluish-tinged red 54 ##STR114## 16 parts ##STR115## red 55 ##STR116## 16 parts ##STR117## red 56 ##STR118## 32 parts ##STR119## green 57 ##STR120## 32 parts ##STR121## neutral blue 58 ##STR122## 32 parts ##STR123## greenish-tinged blue 59 ##STR124## 32 parts ##STR125## greenish-tinged blue
DYEING EXAMPLE
100 parts of wool piece yarn are put, at 50.degree. to 80.degree., into a dyebath which contains 10 parts of crystalline sodium sulfate, 6 parts of 40% acetic acid, 0.5 part of a condensation product of higher aliphatic amines with ethylene oxide and 2 parts of the dye described in Example 1 in 3,000 parts of water. The bath is heated to the boil in the course of half an hour and dyeing is then carried out at the boil for 1 hour. The wool is then rinsed and dried. A uniform blue dyeing is obtained.
Claims
  • 1. A dye of the formula ##STR126## in which D is an organic dye radical which contains at least one group conferring solubility in water, R is a halogenoalkyl radical having 1 to 2 C atoms or a halogenoacryl radical and n is an integer from 1 to 4 and each group of the formula ##STR127## is bonded to D via an aromatic carbon atom.
  • 2. A dye according to claim 1, in which D is a dye radical of the anthraquinone, azo, dioxazine or phthalocyanine series, which contains 1 to 3, sulfo groups.
  • 3. A dye according to claim 1, in which R is a radical of the formula --CH.sub.2 Cl, --CH.sub.2 Br, --CCl.dbd.CH.sub.2, --CBr.dbd.CH.sub.2, --CHCl--CH.sub.2 Cl or --CHBr--CH.sub.2 Br.
  • 4. A dye according to claim 1, wherein D is a radical of the anthraquinone series or azo series which contains 1 to 2 sulfo groups and n is 1 or 2.
  • 5. A dye according to claim 1, of the formula ##STR128## in which R.sub.1 is hydrogen, cycloalkyl, low-molecular alkyl, aralkyl or aryl, Ar is an arylene group, Z is an .alpha.,.beta.-dichloropropionyl group, an .alpha.,.beta.-dibromo-propionyl group, an .alpha.-chloro-acryloyl group, an .alpha.-bromo-acryloyl group or a chloroacetyl group, m is 1 or 2 and p is 1 or 2, and in which ring a is unsubstituted or substituted by hydroxyl or halogen.
  • 6. A dye according to claim 1, of the formula ##STR129## in which A.sub.1 and A.sub.2 are each an unbranched or branched alkylene group having not more than 5 carbon atoms and Z is an .alpha.,.beta.-dichloro-propionyl group, an .alpha.,.beta.-dibromo-propionyl group, an .alpha.-chloro-acryloyl group, an .alpha.-bromo-acryloyl group or a chloroacetyl group, and in which the ring a' is unsubstituted or substituted by hydroxyl or halogen.
  • 7. A dye according to claim 5, in which R.sub.1 is hydrogen, cycloalkyl or a low-molecular alkyl radical, Ar is a phenylene radical which is unsubstituted or substituted by methyl and Z is the dibromopropionyl group.
  • 8. A dye according to claim 6, in which Z is the dibromopropionyl group.
  • 9. The dye according to claim 5, of the formula ##STR130##
  • 10. A dye according to claim 7, wherein R.sub.1 is isopropyl or isobutyl.
  • 11. A dye of claim 1, wherein D is a diazo dye radical having a diazo component of the benzene or naphthalene series and substituted on the coupling component by ##STR131## where n is 1 or 2 and ##STR132## is .alpha.,.beta.-dichloro-propionyl, .alpha.,.beta.-dibromopropionyl, .alpha.-chloro-acryloyl, .alpha.-bromo-acryloyl, or chloroacetyl.
  • 12. A dye according to claim 11, in which the coupling component is the radical of a naphtholsulfonic acid, a naphtho-(1,2-d)-imidazole, an acetoacetarylide, a 5-amino-pyrazole or a pyrazol-5-one.
  • 13. A dye according to claim 12, in which ##STR133## is the dibromopropionyl group.
Priority Claims (1)
Number Date Country Kind
9017/79 Oct 1979 CHX
US Referenced Citations (9)
Number Name Date Kind
2722534 Randall Nov 1955
3007762 Wegmann et al. Nov 1961
3365472 Buehler et al. Jan 1968
3498967 De Montmollin et al. Mar 1970
3843695 Buehler et al. Oct 1974
3857864 Schwander et al. Dec 1974
3862192 Schwander et al. Jan 1975
3923778 de Montmollin et al. Dec 1975
4101547 Mislin et al. Jul 1978
Foreign Referenced Citations (1)
Number Date Country
2640615 Mar 1977 DEX
Non-Patent Literature Citations (2)
Entry
Liebigs Annalen der Chemie, vol. 343, pp. 207, 1905.
Liebigs Annalen der Chemie, vol. 361, pp. 113, 1908.