JPH05310750A - Gold-cyclam complex - Google Patents

Abstract

PURPOSE:To provide a new complex comprising gold and a cyclam derivative and useful for separating gold, etc. CONSTITUTION:The gold-cyclam complex comprises a cyclam derivative selected from a group consisting of a non-substituted cyclam of the formula, a phenol- substituted cyclam, a pyridine-substituted cyclam, a phenol-substituted monooxocyclam and a pyridyl-substituted monooxocyclam and gold coordinated with the four nitrogen atoms of the cyclam derivative. When an oleophilic cyclam derivative produced by repiacing a hydrogen atom bonded to a carbon atom of the cyclam ring with >=10C alkyl is used as the ligand, gold is efficiently isolated from a mixture of gold with other metals.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a novel gold-cyclam complex which is useful for gold isolation and the like.

[0002]

[Prior Art and its Problems] Conventionally, the cyclam (1,
4,8,11-Tetraazacyclotetradecane) has been used for sequestering metal ions (eg Inorg. Chem. 1
965, 4, 1102), but its gold (III) complex is unknown.
This is strange in view of the properties of gold (III), which is widely disclosed in the literature for forming tetramine (eg, tetraammonium, bisethylenediamine, etc.). It has been widely practiced to purify gold from a metal mixture containing gold, but it is unavoidable that trace impurities are mixed in purified gold, and a more reliable and simple gold isolation method is demanded. ..

[0003]

OBJECTS OF THE INVENTION The present invention aims to provide a gold-cyclam complex which has not been isolated in the past and is particularly useful for gold isolation.

[0004]

The present invention provides a cyclam derivative selected from the group consisting of unsubstituted cyclams, phenol-substituted cyclams, pyridyl-substituted cyclams, phenol-substituted monooxocyclams and pyridyl-substituted monooxocyclams. A gold-cyclam complex composed of the cyclam derivative and gold coordinated to four nitrogen atoms. The hydrogen atom bonded to the carbon atom of each of the above-mentioned cyclams may be substituted with an alkyl group.

The present invention will be described in detail below. The cyclam derivative-gold complex (Chemical Formula 1) is produced by reacting a cyclam derivative such as an unsubstituted cyclam (Chemical Formula 2) with a gold compound such as sodium chloroaurate. NaAuCl ₄ .2H ₂ O specific to equivalent for example an unsubstituted cyclam (formula 2)
After treatment for 1 hour in refluxing acrylonitrile for 1 hour, a yellow needle crystal, "gold (III) -yne" complex (Chemical formula 1) is formed, which is subsequently separated by ion exchange column chromatography (eluent is 3N hydrochloric acid). And purified by recrystallization or the like with a 1N aqueous solution of perchloric acid. The reaction yields only a single product (eluent is methanol-10%
Sodium chloride = 1: 1, Rf = 0.6). The complex of Formula 1 is stable as a solid and in acidic solutions.

[0006]

According to pH titration of the complex of the formula (1) with 0.1 molar sodium hydroxide (25 ° C., I = 0.1 molar sodium perchlorate), proton desorption occurs at _a pK _a value of 5.4.
This is because the deprotonation of the secondary amine of the complex of (Chemical formula 1) occurs to convert it to the corresponding deprotonated compound (Chemical formula 3) and the return to (Chemical formula 1) by protonation of (Chemical formula 3), This is due to the equilibrium between Chemical formula 1) and Chemical formula 3. The complex of (Chemical Formula 3) is p
CT absorption band (N _max of λ _max 360 nm (ε2160) above H7
^- → Au (III)), and this absorption band disappears when (Chemical formula 3) returns to (Chemical formula 1). However, the complex of (Chemical Formula 3) is unstable in an alkaline solution and gradually decomposes to precipitate metallic gold. Dissociation of protons from the NH of cyclam in such low pK _a value other metals - is that not seen in cyclam complexes.

Therefore, for example, when an unsubstituted cyclam is reacted with a mixture of gold and zinc, a complex in which the central metal of (Chemical Formula 1) and (Chemical Formula 1) is substituted with zinc is formed as a mixture. When the pK _a value of this mixture is 5.4 or more, the gold complex (Chemical formula 1)
When only the secondary amine hydrogen is eliminated to generate equilibrium with (Chemical Formula 3) and the solution containing the complex of (Chemical Formula 3) is made alkaline, (Chemical Formula 3) is decomposed and gold is isolated, Remains as a complex in the solution. Therefore, it becomes possible to easily isolate gold from a mixture of metals by using cyclam derivatives such as unsubstituted cyclam. pD1
The ¹³ C NMR spectrum of (Chemical Formula 1) in D ₂ O in Fig. 3 shows only three kinds of peaks at δ31.9, 53.2 and 59.1 ppm, while the spectrum of (Chemical Formula 3) in pD7 has a peak δ32.4 , 54.5 and 59.2 ppm, which show a rapid equilibrium between (Chemical formula 1) and (Chemical formula 3), so that the four nitrogen atoms are equivalent.

When a phenol-substituted cyclam is used in place of the cyclam (Chemical Formula 2) and is similarly treated with NaAuCl ₄ , a gold (III) inclusion complex (Chemical Formula 4) is produced as a main product, but the treatment time is long. This results in unidentified by-products. ¹³ C NMR spectrum of (Chemical Formula 4) (pD1, D ₂ O
(Middle) shows the peak of quaternary carbon having a phenol side chain at δ5
Shown at 9.8 ppm. Reversible deprotonation of the complex of (Chemical Formula 4) occurs at the carbon adjacent to NH at pK _a 5.0 to produce (Chemical Formula 5). This is evidenced by the very large chemical shift of the quaternary carbon to δ70.2. In this process CT absorption occurs at λ _max 356 nm. The second deprotonation of the phenol-substituted cyclam complex (Chemical formula 4) is pH
Occurs at the hydroxyl group of phenol as the temperature rises [UV absorption from λ _max 268 nm (ε6000) to 286 nm (ε5200)
To a complex represented by (Chemical Formula 6), and the second elimination does not occur unless the first elimination occurs. This is clear evidence that gold (III) is strongly acidic and extends only in the plane formed by the four nitrogens. (Formula 5) and pK _a values of equilibrium (of 6) 8.3 Phenol p
And K _a value 9.8, and the pK _a value of the same complex of other cations (copper 9.2, nickel 6.3, zinc 5.8) should be compared with. The weaker acidity than that of nickel and zinc complexes of phenolic hydrogen of gold (III) complex (Chem.
^- ) Caused by the effect of the d ⁸ configuration of the donor and gold (III). The phenolate absorption band (λ _max 286 nm, ε2600) of the gold (III) complex (Chemical Formula 6) is determined by the zinc (II) complex (λ _max 288 nm, ε5200), 2H ⁺ complex (λ _max 293 nm).
nm, ε3700) or nickel (II) complexes. This implies that there are somewhat similar metal-oxygen interactions.

Pyridyl-substituted cyclams likewise have NaAuCl ₄
Reacts with to form a gold (III) inclusion complex (Chemical Formula 7). The pH of the complex was titrated with 0.1 molar sodium hydroxide to give a p
_{K a 5.0 (25 ℃, I} = 0.1 mol sodium perchlorate) occurs deprotonation with, which is the deprotonation of the secondary amine which is adjacent to the tertiary carbon having a pyridyl group. In this process, CT absorption λ _max 358 nm and ε 2960 appear. The nitrogen of the pyridyl group has little basicity (pK _a <
2). Both (Chemical Formula 4) and (Chemical Formula 7) are stable in an acidic solution, but are unstable in neutral to alkaline conditions. When the unsubstituted monooxocyclam was similarly treated with an equivalent amount of NaAuCl ₄ .2H ₂ O at room temperature for 2 days, a different "gold (I
II) -out ”complex (Chemical Formula 8) is formed in which the gold is coordinated to 3 nitrogens and 1 chlorine. Thus, a complex containing gold as a central metal coordinated to four nitrogens does not form from the unsubstituted monooxocyclam.

[0011]

On the other hand, when the phenol-substituted monooxocyclam or the pyridyl-substituted monooxocyclam is treated in the same manner, the phenol-substituted monooxocyclam-gold complex of (formula 9) and the pyridyl of (formula 10), respectively are obtained. A substituted monooxocyclam-gold complex (single product) is formed. Unlike other divalent metal complexes, the characteristic of the gold (III) complex is its extreme stability to acid, and (Chemical Formula 9) and (Chemical Formula 10) are complex even when coexisting with 1N perchloric acid. Does not cause deprotonation, which decomposes Under the same conditions
In a complex in which gold, which is the central metal of (Chemical Formula 10), is replaced with zinc, copper, nickel or the like, deprotonation easily occurs and dissociates into a free ligand and a divalent metal. In other words, there is virtually no anionic N ^- electron that the imide anion strongly binds to gold (III) and shares for protonation. So the gold (III) ion at the center of the cyclam is a stronger acid than H ⁺ . In the same manner as the above-mentioned cyclam complex, in the complexes of (Chemical Formula 9) and (Chemical Formula 10), deprotonation from the phenol group (pK _{a to} 8.8) and secondary amine [pK _a
～6.9 (Formula 9) and pK _a to 6.4 (of 10)] is produced.
The above-mentioned cyclam derivative used for gold purification by selective extraction of gold is preferably lipophilic, and the complexes of (formula 11), (formula 12) and (formula 13) were used for gold extraction.
When the complexes of (Chemical formula 11) and (Chemical formula 12) were used, the extraction of gold (III) was efficiently performed, but in (Chemical formula 13), the extraction of gold (III) hardly occurred.

[0013]

[0014]

[0015]

[Examples] Next, examples of producing the gold-cyclam complex according to the present invention will be described, but the examples do not limit the present invention. All reagents in each example were commercially available as analytical reagents and were used without further purification. The product was identified by NMR, UV, IR and atomic absorption spectra and elemental analysis. ¹ H (400M
Hz) and ¹³ C (100 MHz) NMR spectra were measured using JEOL GX-400 at 35 ° C. using D ₂ O as a solvent and 3-trimethylsilyl-1-propanesulfonate (d ₄ ) as an internal standard.
Recorded using a spectrometer. IR and UV spectra were recorded on FTIR-4200 from Shimadzu and U-3200 from Hitachi, respectively. Atomic absorption spectrum of gold hollow cathode lamp (made by Hamamatsu Photonics Co., Ltd.)
Was recorded on a Shimadzu AA-646 spectrophotometer. Ion exchange and thin layer chromatography are performed on Dowex 50X4 (50-100 mesh, H ⁺ type) and
Merk Art5554TLC plates (silica gel 60F ₂₅₄₎ was performed using.

[0016]

Further, potentiometric titration was carried out as follows. Equivalent HC
an aqueous solution (25 ml) of gold (III) or another metal complex (1.00 × 10 ^-3 mol) containing l, carbonate free
Titration with a 0.100 molar aqueous sodium hydroxide solution. pH
Values were read on an Orion 811 digital pH meter. The temperature was maintained at 25.00 ± 0.05 ° C. -log [H ⁺ ] values were evaluated with a pH meter reading corrected for -0.08 pH unit. A stream of moist argon was passed to keep all aqueous solutions out of contact with air. The electrode system was prepared with a pH 7.00 standard buffer solution and checked using a theoretical curve made by titrating 0.01 molar sodium hydroxide with 4.00 × 10 ⁻³ molar hydrochloric acid in the low and high pH regions.

Further, gold (III) was extracted as follows. In a 30 ml round bottom flask, 5 ml of the first aqueous solution containing 1 mmol of NaAuCl ₄ dissolved in 1N hydrochloric acid was added at 30 ° C. at 25 ° C. with 2.0 mmol of the ligand dissolved in 5 ml of chloroform. Stir for minutes. After careful phase separation, the aqueous solution was analyzed by an atomic absorption spectrophotometer to detect the gold (III) remaining unextracted. The chloroform phase was then stirred with 5 ml of a second aqueous solution (diluted water) for 30 minutes at 60 ° C. The second aqueous solution was analyzed to detect unextracted gold (III) remaining.
The results are shown in Table 2. All operations were repeated 3 times and the values were maintained within ± 5%.

Example 1 Cyclam (1.0 mmol) and sodium chloroaurate dihydrate (NaAu) dissolved in 20 ml of acrylonitrile.
Cl ₄ .2H ₂ O (398 mg, 1.0 mmol) was refluxed for 1 hour, and then 10 ml of 0.1 N hydrochloric acid aqueous solution was added thereto, and insoluble substances (Au ⁰ etc.) were filtered off. After the filtrate was concentrated, the residue was isolated by Dowex 50X4 ion exchange column chromatography (eluent was 3N hydrochloric acid) and purified by recrystallization from a 1N aqueous solution of perchloric acid to obtain a highly pure crystalline substance. .. Elemental analysis values, UV and ¹³ C NMR spectral spectral data are summarized in Table 1. The material isolated from Table 1 was identified as the cyclam gold complex (Formula 1).

Example 2 A highly pure crystalline substance was obtained in the same manner as in Example 1 except that a phenol-substituted cyclam was used instead of the cyclam. Elemental analysis values, UV and ¹³ C NMR spectral spectral data are summarized in Table 1. The material isolated from Table 1 was identified to be a phenol-substituted cyclam gold complex (Chemical Formula 4).

Example 3 A highly pure crystalline substance was obtained in the same manner as in Example 1 except that pyridyl-substituted cyclam was used instead of cyclam. Elemental analysis values, UV and ¹³ C NMR spectral spectral data are summarized in Table 1. The material isolated from Table 1 was identified as a pyridyl-substituted cyclam gold complex (Chemical Formula 7).

[0022] Reference Example acrylonitrile 20 ml mono-oxo cycle was dissolved in ram (1.0 mmol) and chloroauric sodium dihydrate _{(NaAuCl 4 .2H 2 O, 398} mg, 1.0 mmol) was stirred for 2 days at room temperature (60 ° C. The ligand decomposes). Thereafter, an aqueous hydrochloric acid solution was added and filtered off in the same manner as in Example 1, and further purified to obtain a highly pure crystalline substance. Elemental analysis values, UV and ¹³ C NMR spectral spectral data are summarized in Table 1. The material isolated from Table 1 was identified as a monooxocyclam gold complex (Chemical Formula 8).

Example 4 A highly pure crystalline substance was obtained in the same manner as in Reference Example except that phenol-substituted monooxocyclam was used instead of monooxocyclam. Elemental analysis value, UV and ¹³
The data of the CNMR spectrum spectrum is summarized in Table 1. The material isolated from Table 1 was identified as a phenol-substituted monooxocyclam gold complex (Chem. 9).

Example 5 A highly pure crystalline substance was obtained in the same manner as in Reference Example except that pyridyl-substituted monooxocyclam was used instead of monooxocyclam. Elemental analysis value, UV and ¹³ C
The data of the NMR spectrum spectrum are summarized in Table 1.
The material isolated from Table 1 was identified as a pyridyl-substituted monooxocyclam gold complex.

Example 6 First, C ₁₅ H ₃₂ -cyclam was synthesized as follows.
1,9-Diamino-3,7-diazanonane (15 mmol) and 2-octadecenoic acid ethyl ester [CH
_{3 (CH 2) 14 CH = CHCO} 2 C 2 H 5 ] (15 mmol) was refluxed for 3 weeks at 500 milliliters of methanol. After evaporating the methanol, the residue was purified by silica gel chromatography and recrystallized from a n-heptane / toluene mixture to give the amide as colorless needles in 15% yield. The above amide was added to B in tetrahydrofuran.
Reduction with ₂ H ₆ produced colorless crystals of C ₁₅ H ₃₂ -cyclam in a yield of 27%. Its melting point is 114.
The peaks of ¹ H NMR (in CDCl ₃ ) at 0 to 115.0 ° C. are as follows. δ0.88 (3H, t, J6.8Hz, CH ₃ ), 1.26 (28
H, m, C (CH ₂ ) ₁₄ C), 1.72 (2H, q, J2.6
Hz, CCH ₂ C), 1.74 (2H, m, CCH ₂ C), 1.
84 (4H, br, NH), 2.45 to 2.95 (15H, m, NCH
₂ C).

1.0 mmol of NaAuCl ₄ and the same concentration of copper (II) and nickel dissolved in 5 ml of 1N hydrochloric acid
A mixture of (II), iron (III), manganese (II), cobalt (II) and palladium (II) was prepared in the same manner as 2.0 mmol of 2.0 mmol dissolved in 5 ml of chloroform. C ₁₅ H ₃₂ - cyclam (formula 1
1), C ₁₆ H ₃₃ -cyclam (Chemical formula 12) and C ₁₆ H ₃₃ -dioxocyclam (Chemical formula 13), respectively, and stirred at 25 ° C for 30 minutes. The gold (III) ions remaining in the aqueous solution I after careful phase separation were measured by an atomic absorption spectrophotometer. Then, the chloroform layer containing gold (III) as a complex was re-extracted with 5 ml of distilled water for 30 minutes at 60 ° C., and gold (III) extracted in the resulting aqueous solution II was analyzed. The results are shown in Table 2. The best gold (III) extraction was achieved with the cyclam derivative (Chem. 11) in yields over 94%. Re-treatment with chloroform extracted almost all the remaining gold (III) (over 97% overall yield). The good ligand for the second chloroform treatment was (Chemical Formula 12), and the dioxocyclam derivative (Chemical Formula 13) was not effective in this case.

(Chemical formula 11) and (Chemical formula 12) show a remarkable uptake selectivity for gold over other metal ions (copper, nickel, iron, manganese, cobalt and palladium), and 78% and 75% in chloroform. % Gold (III) extraction efficiency was achieved. Gold (III) bound to (Chemical formula 11) and (Chemical formula 12)
Ions are 81% and 75% in distilled water (pH ~ 3), respectively.
Was isolated with a recovery rate of. For comparison, a copper complex of (Chemical Formula 11) was prepared and injected into distilled water to try to isolate copper, but extraction did not occur.

[0028]

INDUSTRIAL APPLICABILITY The present invention provides a cyclam derivative such as an unsubstituted cyclam, a phenol-substituted cyclam, a pyridyl-substituted cyclam, a phenol-substituted monooxocyclam and a pyridyl-substituted monooxocyclam, and coordinated to four nitrogen atoms of the derivative. It is a gold-cyclam complex composed of gold (claim 1). Gold present invention - cyclam complexes are novel complex compound, the complexes other metals - deprotonation of the hydrogen bonded to one nitrogen atom of cyclam ring lower than that of cyclam complexes pK _a is generated. The resulting deprotonated product is alkaline and unstable and decomposes to facilitate isolation of metallic gold. Therefore, gold can be isolated from a mixture of gold with copper, nickel, cobalt, zinc, etc. by adjusting the pH.

Claims (1)

[Claims] 1. A cyclam derivative selected from the group consisting of unsubstituted cyclam, phenol-substituted cyclam, pyridyl-substituted cyclam, phenol-substituted monooxocyclam and pyridyl-substituted monooxocyclam, and four nitrogen atoms of the cyclam derivative. A gold-cyclam complex consisting of and coordinated to gold.