Norman C. Li

Dinonyl naphthalene sulphonic acid and tri-n-octylamine as liquid ion-exchangers for the study of Fe(III) and In(III)-chloride complexes

Abstract The stability constant of the 1:1 Fe(III)-chloride complex at ionic strengths varying from 0·20 to 1·00 is independent of whether H+ or Na+ is the cation of the perchlorate ion. The specific ion effect on the stability of the FeCl2+ complex found by Coll et al., above 5 M, therefore is absent at these lower ionic strengths. For In(III), substitution of Na+ for H+ as cation of the perchlorate ion decreases the log K1 of InCl2+ by about 0·3 at ionic strengths of one and two. The presence of the specific ion effect on the InCl system at ionic strengths one and two and the absence of the effect on FeCl system is not surprising since In(III) forms much more stable complexes with Cl− than Fe(III). No extraction of the Fe(III) and In(III) by the anionic exchanger, tri-n-octylamine hydrochloride, in perchloric acid solutions, less than 2 M, has occurred. This indicates that perchlorate ion does not form negatively charged complex with Fe(III) or In(III) in the organic phase. The distribution coefficients of Fe(III) and In(III) are directly second power dependent upon the tri-n-octylamine hydrochloride concentration in the benzene phase, suggesting that the negatively-charged complexes FeCl52− and InCl52− complexes are formed in the organic phase.

4-methyl-pyridine adducts of copper (II) β-diketone chelates

Abstract Spectrophotometric studies in the visible region have been made on benzene solutions of Cu(chelate)2 [chelate = the hexafluoroacetylacetonate ion (HFacac), the thenoyltrifluroacetonate ion (TTA), the trifluoroacetylacetonate ion (TFacac) and the acetylacetonate ion (acac)] with increasing amounts of 4-methyl-pyridine (4-me-py). All form 1:1 adducts of the type Cu(chelate)2·4-me-py which, with the exception of Cu(acac)2·4-me-py, are very stable. The room-temperature formation constant of this adduct has been determined as approximately 101.mole−1. Again with the exception of Cu(acac)2, they all form 1:2 adducts of the type Cu(chelate)2·(4-me-py)2. Solid complexes have been isolated and analysed. It is suggested that the 1:1 and 1:2 adducts are definite compounds and that, in the latter, the second molecule of base is not simply trapped in the lattice.

Metal complexes involved in solvent extraction and their role in the synergistic effect

Abstract Solid ternary complexes of the type M(TTA)2·TOPO (M = Zn2+ and Cu2+, TTA = thenoyltrifluoroacetone anion and TOPO = tri-n-octyl phosphine oxide) have been prepared and investigated. The phosphorus nuclear magnetic resonance method has been used to determine the equilibrium constant of the reaction Zn(TTA)2 (org.) + TOPO (org.) = Zn(TTA)2·TOPO(org.). This was found to be approximately 10 1/mole in anhydrous carbon tetrachloride medium. It was also shown that in the same medium, the less basic TBEP (tri-n-butoxyethyl phosphate) did not coordinate with Zn(TTA)2 to any measurable extent. In fact, the corresponding ternary complexes M(TTA)2·TBEP could not be isolated. Proton magnetic resonance studies also afford evidence for the reaction: Zn(TTA)2·2H2O + TOPO = Zn(TTA)2·TOPO + 2H2O in carbon tetrachloride medium. It is suggested that the phenomenon of synergism may be due to the enhanced solubility (in the organic phase) of neutral metal chelates caused by adduct formation with ligands such as TOPO.

Dinonyl naphthalene sulphonic acid as a liquid cation-exchanger for complex studies

Abstract The extraction of Co(II), Zn(II), Mn(II), Fe(III) and In(III) into heptane containing dinonyl naphthalene sulphonic acid, HD from aqueous perchloric acid solutions, has been investigated, using the radioactive tracer technique. The distribution coefficients for M(II) and M(III) are inversely second power and third power, respectively, dependent upon the hydrogen ion concentration in the aqueous phase, and directly first power dependent upon the HD concentration in the heptane phase. The formation constants of In(III) complexes of glycolate, bioxalate and Co(II) complexes of bioxalate have been determined by use of HD in heptane as a liquid cation-exchanger. For Co(II)-bioxalate, it has been demonstrated that the formation constants agree with values obtained by using resinous cation-exchanger. Since the use of liquid ion-exchanger enables one to analyse both the aqueous and non-aqueous phases, whereas in resinous cation-exchange experiments it is not convenient to analyse the non-aqueous phase, it is of decided advantage to demonstrate that the liquid ion-exchanger can be used for complex studies.

METAL COMPLEXES IN SOLVENT EXTRACTION STUDIES. III. PREPARATION AND INVESTIGATION OF BINARY AND TERNARY COMPLEXES

Abstract Some ternary complexes of the type M(chelate) 2 S x [M = UO 2 2+ , Cu 2+ , Zn 2+ , Ni 2+ , Co 2+ , chelate = TTA (thenoyltrifluoroacetone anion), S = TBP (tri-n-butyl phosphate), TBEP (tri-n-butoxyethyl phosphate, TOPO (tri-n-octyl phosphine oxide), 4-me-py (4-methyl pyridine), TPPO (tri-phenyl-phosphine oxide)] have been prepared and investigated. Preliminary work has also been carried out with HFacac (hexafluoroacetylacetone anion), TFacac (trifluoroacetylacetone anion) and acac (acetylacetone anion) as chelates. The compounds Zn(HFacac) 2 · x H 2 O ( x = 1 and 2), Zn-(HFacac) 2 (TOPO) 2 , Cu(HFacac) 2 TOPO, Co(acac) 2 (4-me-py) 2 , UO 2 (acac) 2 ·4-me-py and UO 2 (acac) 2 (TPPO) 3 have also been isolated. Solvent extraction studies show that the synergistic extraction of 65 Zn depends upon the nature of the chelate and of S. It is suggested that the phenomenon of synergism involves both the stability of M(chelate) 2 · x H 2 O and M(chelate) 2 S x and further, that the bonding of S, which is directly to the metal, is weak and comparable to solvation or adduct formation.

COPPER(II) AND COBALT(II) COMPLEXES OF PYRIDINE-2-CARBOXAMIDE AND PYRIDINE-2-CARBOXYLIC ACID

Abstract The formation constants of the following have been measured with a polarographic method: binary copper(II) complexes of pyridine-2-carboxamide (picolinamide) and pyridine-2-carboxylic acid (picolinic acid), a ternary copper(II) complex of picolinic acid and imidazole, and a binary copper(I)-imidazole complex. The larger formation constant for picolinic acid over picolinamide is ascribed to the greater chelating ability of a carboxylate group over an amide carbonyl oxygen. The crystal and molecular structure of diaquobis(picolinato)cobalt(II) dihydrate, [Co(H2O)2(pc)2].2H2O, has been determined from three-dimensional MoKα X-ray collected by the multiple-film Weissenberg method. The unit cell dimensions are: a=9.89 ± 0.02 A, b=5.17 ± 0.01 A, c=17.50 ± 0.06 A, β=123.8 ± 0.4°. The space group is P21/c, and the calculated density is 1.67 g cm−3 with two formula weights per cell. The measured density is 1.67 g cm−3. The structure was solved by the Patterson method and refined by a least-squares method....

Adducts of copper(II) β-diketone chelates with tertiary alkylamines and alkylamine hydrochlorides

Abstract Adduct formation of Cu(chelate)2 (chelate = anion of thenoyltrifluoroacetone, TTA, and trifluoroacetylacetone, TFA) with alkylamines and alkylamine hydrochlorides, S (S = tri-n-butylamine, TBA, tri-n-hexylamine, THA, tri-n-octylamine, TOA, tri-n-laurylamine, TLA, tri-n-hexylamine hydrochloride, THA·HCl, tri-n-octylamine hydrochloride, TOA·HCl and tri-n-laurylamine hydrochloride, TLA·HCl) have been studied spectrophotometrically. Visible and i.r. spectra suggest that alkylamines and alkylamine hydrochlorides form different adducts through bonding of different atoms. In the alkylamines the nitrogen atom is bonded to copper(II) while in the alkylamine hydrochlorides the chlorine atom is bonded to copper(II). Equilibrium constants for the adduct-formation reactions are calculated from the spectral change upon addition of the adduct-forming ligands. It is found that alkylamines and alkylamine hydrochlorides do not interact with Cu(chelate)2 to the same extent. Furthermore, the complexes species, TOA·HTTA and TOA·HCl·HTTA, do not interact with Cu(chelate)2.

Ageing of SRC liquids

Abstract The ageing characteristics of a 30 70 (wt%) blend of SRC-I and SRC-II and of a SRC-II middle distillate (boiling-point range 450–565K), have been studied. Viscometric, ultimate analysis, solvent separation, gel permeation chromatography, and 600-MHz n.m.r. measurements have been used to monitor the ageing properties of the SRC liquids under various conditions. The viscosity of the blend increases significantly in ten days with oxygen bubbling through at 335K. However, copper, in addition to oxygen, is necessary to change the viscosity of the middle distillate significantly. For the blend, there is a rectilinear increase in log viscosity with increasing wt% of toluene-insolubles formed during oxygenageing. There is also a rectilinear decrease in log viscosity with decreasing content of toluene-insolubles resulting from hydroprocessing of the blend with NizMo catalyst. These observations indicate that under conditions of oxidative degradation the formation and content of larger molecular-size tolueneinsolubles are mainly responsible for the increased viscosity of the blend. The middle distillate does not contain toluene-insolubles, and oxygen-ageing occurs only in the presence of copper. Oxidative coupling of phenols is proposed as an ageing mechanism for both the blend and the middle distillate.

Ageing of SRC-II middle distillate from Illinois no 6 coal. II: Further evidence of phenolic oxidative coupling in coal-derived liquids

Abstract Individual phenolic compounds in an SRC-II middle distillate were quantified before and after ageing in the presence of Cu and O2. The concentration of each phenolic constituent decreased, indicating that they are consumed by a reaction that occurs during ageing. After ageing, a pentane-insoluble precipitate formed that was not present before ageing. Bulk characterization of this ageing product by low-voltage high-resolution mass spectrometry shows that it contains dimers, trimers, tetramers, etc., of phenols. These are the same kinds of products known to form during phenolic oxidative coupling reactions. This observation is taken as direct physical evidence that supports an earlier hypothesis that phenolic oxidative coupling reactions occur during ageing of SRC-II middle distillate in Cu O 2 environments.

Adducts of copper (II) β-diketone chelates with phosphorus esters☆

Abstract Spectrophotometric studies in the visible region have been made on benzene solutions of Cu(chelate)2 [chelate = anion of hexafluoroacetylacetone (HFA), thenoyltrifluoroacetone (TTA), trifluoroacetylacetone (TFA) and acetylacetone (AA)] with phosphorus esters, S [S = tri-n-octyl phosphine oxide (TOPO). tri-phenyl phosphine oxide (TPPO), tri-n-butyl phosphate (TBP) and tri-phenyl phosphate (TPP)]. For each of the four phosphorus esters, the acidity of the Cu(chelate)2 increases in the order: CU(AA)2