Alkaline Earth Metal Salts Research Articles

Hidrólise seletiva de carboxiamidas de resíduos de asparagina e glutamina em colágeno: preparação e caracterização de matrizes aniônicas para uso como biomateriais

This work describes the selective hydrolysis of carboxyamide groups of asparagine and glutamine of collagen matrices for the preparation of negatively charged collagen biomaterials. The reaction was performed in the presence of chloride and sulfate salts of alkaline and alkaline earth metals in aqueous dimethylsulfoxide solution and, selectively hydrolysis of carboxyamide groups of collagen matrices was promoted without cleavage of the peptide bond. The result is a new collagen material with controlled increase in negative charge content. Although triple helix secondary structure of tropocollagen was preserved, significative changes in thermal stabilities were observed in association with a new pattern of tropocollagen macromolecular association, particularly in respect microfibril assembly, thus providing at physiological pH a new type of collagen structure for biomaterial preparation, characterized by different charge and structural contents .

Thermal polymerizations of alkali and alkaline earth 4-vinylbenzoates in bulk

Thermal polymerizations of alkali and alkaline earth 4-vinylbenzoates (4-VBAs) in bulk were investigated. The relative reactivity of the alkali salts decreases in the following order: K > Na > Li, which is in reverse order to that of alkali methacrylates. In the polymerization of K-4-VBA at 240°C, the number-average molecular weight decreases with increasing reaction time, although the yield of polymer increases. The polymerization of the K salt proceeds as long as the crystallinity of the monomeric salt is maintained, and is terminated when there is no crystalline compound in the reaction mixture left. The relative reactivity of the alkaline earth salts decreases in the following order: Mg > Ca > Sr >> Ba. The polymerization of Mg-4-VBA proceeds rapidly at 240°C in the initial stage (30 min) and then levels off, however, the appearance of the reaction mixture still remains crystalline.

高塩基性有機金属塩の熱間潤滑効果とその作用機構

A new method to present a lubricating composition which can effectively prevent seizure during hot rolling of stainless steels is proposed: both "the Principles of Hard and Soft Acids and Bases" for improving chemisorption force and "the super fine particles" for decreasing metal/metal contacts. The degree of seizure and coefficient of friction of mineral oil based organic metal salts, lithium grease based graphite, conventional hot-rolling oil are estimated by disc-block type friction test at elevated temperature. Effects of lubricants on roll oxide film are investigated by model hot rolling mill. Chemical reactivity of lubricants for a fresh and oxide surface is investigated by XPS.The results obtained are as follows; (1) A lubricating composition included overbased metal sulfonates was effective for preventing seizure by action of a large quantity of calcium carbonate (average particle diameter < 100 Å) in hot metalworking. (2) Calcium sulfonates have the highest lubricity among the alkaline earth salts of the sulfonic acid having the same base number and a higher base number is better. (3) It is made clear that the overbased Calcium sulfonates change FeO into FeO·Ca0 on steels in rolling bite, and prevent roll oxide film from growing up.

Epoxidation of β-Isophorone over a Titania–Silica Aerogel: Effect of Catalyst Pretreatments with Bases

The epoxidation of β-isophorone with TBHP and an amorphous mesoporous titania–silica aerogel, containing 20 wt% TiO2, has been investigated. The nature of side reactions and the possibility of suppressing them by modification of the catalyst with bases was studied. The as-synthesized (unmodified but calcined) aerogel afforded only moderate selectivity to epoxide (36–87%) in the temperature range of 343–373 K. 4-Hydroxy-isophorone and α-isophorone were the major by-products, formed in isomerization reactions of product and reactant, respectively, and catalyzed by acidic sites present on titania–silica. The selectivity to epoxide could be improved by pretreatment of the aerogel with neutral or weakly basic alkali or alkaline earth metal salts. Treatment of the aerogel with aqueous NaOAc followed by recalcination at 873 K afforded 94% selectivity at 90% peroxide conversion. Application of stronger bases was detrimental to the epoxidation activity and selectivity.We propose that the improved selectivity is due to ion exchange between the weakly basic additive and the surface Brønsted sites (silanol groups). Neutral salts are preferentially anchored to the polar (acidic) surface sites and reduce their accessibility for the more bulky and less polar reactant. The detrimental effect of strong bases is partly due to excess basicity of the catalyst after pretreatment, as the side reactions are also catalyzed by bases. Besides, prolonged treatment with NaOH partially hydrolyzed the Ti–O–Si bonds and restructured the material (titania microdomains in the silica matrix), as evidenced by FTIR and Uv-vis spectroscopy. The study of the epoxide ring opening reaction demonstrated the limited relevance ofex situacidity measurements for predicting the role of acid sites in complex epoxidation reactions.

Synthesis, characterization, spectral and thermal properties of metal-hydrazinium nitrilotriacetates

Hydrazine derivatives of the monobasic nitrilotriacetate salts of zinc and alkaline earth metals have been prepared. IR absorption frequencies and thermal properties of these metal-hydrazinium nitrilotriacetates, (N2H5)M[N(CH2COO)3]·xH2O have been defined. All the three -COOH appear to be dissociated in these salts. In thermal decomposition, these salts initially undergo dehydration followed by dehydrazination and via acetate intermediate step to metal oxycarbonates.

5600020 Process for the preparation of alkoxylates using ester compounds as catalyst

According to the invention, the alkoxylation of compounds containing active hydrogen atoms is carried out in the presence of specific alkaline earth metal salts of alkylor alkenylsuccinic monoesters as catalyst. The alkoxylates obtained have a narrow homolog distribution and a good appearance.

Effect of Ammonium on Anion Uptake andDielectric RelaxationIn Laboratory-Grown IceColumns

Inorganic acids or their alkali-metal or alkaline-earth salts are rather insoluble in ice. Ammonium ion, however, enhances the uptake of a variety of anions into the ice matrix. In the specific case of the fluoride this has been known for almost 50 years and attributed principally to isomorphism between the NH4F and ice crystal lattices. We report here that ammonium also enhances the solubility in ice of anions that do not fit easily into the ice structure. With the species pair HCl/NH4Cl we document specific effects of ammonium on anion uptake, static conductivity, and dielectric conductivity in ice. Other ion species for which comparable results have been obtained are mentioned. Possible implications for atmospheric processes are briefly discussed.

97/02496 Compute-aided study on the influence of catalysts on the coal ignition property. (I). Influence of alkali and alkaline earth metal salts on the coal ignition property

97/02496 Compute-aided study on the influence of catalysts on the coal ignition property. (I). Influence of alkali and alkaline earth metal salts on the coal ignition property

A New Fluorescence Optical-Fiber Sensor for Colchicine

A new sensor for determining the colchicine concentration in aqueous solution is described which uses a bifurcated optical fiber and a micrometer-sized flow cell. The sensing membrane, which contains 2-(4-diphenylyl)-6-phenylbenzoxazole (PBBO), can form a nonfluorescent complex with colchicine and quench the membrane fluorescence. The usable determination range covers from 2×10-4 to 2×10-6mol l-1 colchicine. Satisfactory reproducibility, reversibility and a relatively short response time have been realized. Alkali and alkaline earth metal salts as well as various pharmaceutical species have little or no effect on the sensor response. The sensor can be used for determining the colchicine concentration in pharmaceutical tablets with results that are in satisfactory agreement with those obtained by the pharmacopoeial method.

Spectroscopic and thermochemical investigation of alkaline earth metal salts of 2-oximinopropionate

Alkaline earth metal 2-oximinopropionates were prepared by the reaction of sodium 2-oximinopropionate with the respective metal nitrates or chlorides in water at room temperature. These compounds were characterized by infrared and multinuclear NMR spectroscopy and thermogravimetric analysis. The thermal decomposition of the salts occurs in the range 144-188°C and exhibits a trend towards lower temperature with increasing size of the cation. In all cases, the decomposition yields a metal carbonate. The molecular structure of calcium 2-oximinopropionate hydrate was determined by single-crystal X-ray crystallography. Crystal data: C6H10N2O7Ca, MW = 262.24 g/mol, triclinic, space group P͞1 (No.2), a = 8.954(1) Å, b = 9.3851(7) Å, c = 6.2445(7) Å, α = 97.209(8)°, β = 104.917(9)°, γ = 87.250(8)°, V = 503.0(2) Å3, Z = 2, Dcalc = 1.73 g cm–3, R = 0.03 and Rw = 0.04. Key words: crystal structure, alkaline earth, 2-oximinopropionate, thermal decomposition.

Liquid junction potential between different solvents: a junction with an alkaline earth metal salt as electrolyte

The characteristics of the three components of the liquid junction potential (ljp) between different solvents were studied at a junction with an alkaline earth metal salt as electrolyte. An equation was derived for component (a) at a junction with a Z M / Z X type electrolyte and its validity was confirmed experimentally using 2 + /1 - type Mg(ClO 4 ) 2 , Sr(ClO 4 ) 2 and Ba(ClO 4 ) 2 . Alkaline earth metal ions did not contribute appreciably to component (b) at a junction between two aprotic solvents (even when more than 300 mV was expected theoretically), but contributed to some extent at water|aprotic solvent junctions. Component (c) was proved to be independent of electrolyte both at water|aprotic solvent and aprotic solvent|aprotic solvent junctions.

Gas phase salt clusters from electrosprayed alkaline earth colloids

Several distributions of small polynuclear ions of general form [ nM + mA + pS] q+ (where M represents an alkaline earth cation (Mg, Ca, Sr or Ba), n = 2–10, A represents a halide, acetate or nitrate counterion originating in the divalent salt, and S represents an acetic acid or methanol adduct) are detected by FTICR when water/methanol solutions of alkaline earth salts are electrosprayed. For example, the largest cluster ion derived from 6.3 mM solutions of calcium acetate acidified with 2%x acetic acid have n= 10, m = 18, p = 5 and q = 2. Characteristics of these solutions suggest the presence of colloidal dispersions. These characteristics include stability upon aging, light scattering response and the requisite pre-etching of the glass containers. Aqueous mixtures of two group II salts produce mixed-salt cluster ions. For instance, from a mixture of calcium and magnesium acetate we trap mixed-cation clusters characterized by a complete set of binary partitions of n, for n = 2–6. Specifically, the manifold of clusters with four cations contains 4:0, 3:1, 2:2, 1:3 and 0:4 ratios of magnesium to calcium. Isolated alkaline earth clusters react with a low-pressure background of 18-crown-6 (C6) by salt abstraction exclusively. In general, the more facile abstraction from a mixed cluster produces a pair of products in which the neutral conforms to the hard-soft acid-base principle. The reactions of C6 with [MgSr(OAc) 3] + provide evidence for the existence of isomeric clusters at m/z 289. This is supported by bimodal kinetics and preliminary results of ab initio calculations.

Complexation of SEBS-based ionomers with pyridine-unit-containing copolymers in solution and bulk

This paper studies complexation behaviour between block ionomers with metal sulfonate groups and pyridine-group-containing copolymers, i.e. poly(styrene- co-4-vinyl pyridine) (STVP) and poly(methyl methacrylate- co-4-vinyl pyridine) (MVP) in both solution and bulk. The block ionomers based on poly(styrene- b-ethylene- co-butene- b-styrene) (SEBS) with metal sulfonate groups were prepared by sulfonation of SEBS followed by neutralization. In the blend solutions in tetrahydrofuran, intercomponent complexation is evidenced by an unusual increase in the reduced viscosity relative to the solutions of SEBS and the copolymers. This complexation was observed by dynamic light scattering (DLS) measurements to take place at concentrations as low as 0.01 g dl −1. DLS also shows the coexistence of two kinds of complex differing considerably in size, which are formed from STVP with single block ionomers and block ionomer aggregates, respectively. Among the different metal salts of alkali, alkaline earth and transition metals studied, copper and nickel show the greatest capability of complexation. In the solvent-cast blends of ionomer/MVP and ionomer/STVP, T g is much higher than expected for the usual miscible blends, and varies with the blend composition in a way similar to the reduced viscosity of the blend solutions, with a similarly located maximum; this implies that the apparent increase in T g of the blends is caused by complexation which occurs at dilute solution and is preserved in the casting process.

Raman Spectra of Alkali and Alkaline Earth Metal Salts of Inosine 5′-Monophosphoric Acid

Crystalline Li(I), Na(I), K(I), Mg(II), Ca(II), Sr(II), Ba(II) and Cd(II) salts of inosine 5′-monophosphoric acid, H2(IMP), were obtained and characterized by Raman spectroscopy. Splitting of the imidazolic 1480 cm−1 band was observed for the N(7)-bound Ca(IMP)·6H2O, Ba(IMP)·6H2O, Sr(IMP)·6H2O and Cd(IMP)·4H2O compounds. The Li(I), Mg(II), Ca(II) and Cd(II) ions bind directly to the phosphate group, and no direct coordination involving the carbonyl C(6)O group was observed in the compounds reported here. Some Raman spectral features in the 750–700 cm−1 range seem to reflect the nucleoside structure of the inosine moiety

Polymethine dyes based on (benzo-15-crown-5) thiazole

Several monomethinecyanine, merocyanine and styryl dyes were synthesized using a 5,6-(1,4,7,10,13-pentaoxacyclotridecane)-benzothiazole derivative as the starging reageni. A study was made of their spectral characteristics and the effect which complexing with alkaline and alkaline-earth metal salts had on their chromaticity.

Salts are Mostly NOT Ionized

The popular assumption that all salts are totally ionized in aqueous solution is false. Moreover, it is approximated only by alkali metal salts and by salts of alkaline earth metals with high atomic numbers.

Kinetics of Beryllium-Induced Aggregation of Acidic Phospholipid Vesicles

Stopped-flow kinetic measurements were carried out for the aggregation of acidic phospholipid vesicles induced by the addition of BeSO4solution. The phospholipid species examined were dimyristoylphosphatidic acid (DMPA), dimyristoylphosphatidylglycerol (DMPG), and dimyristoylphosphatidylserine (DMPS). For all of these phospholipid vesicles, BeSO4induced a rapid aggregation at extremely low concentration compared with other alkaline-earth metal salts. By increasing the solution pH progressively, the aggregation-inducing effect of BeSO4was promoted increasingly, and the profile of the initial velocity of the aggregation with respect to the salt concentration approached to that observed for the aggregation induced by La3+ion. This result demonstrates that the high activity of BeSO4to induce the aggregation of acidic phospholipid vesicles is attributed to the formation of trivalent complex cation, [Be3(OH)3]3+, due to the hydrolysis of Be2+in an aqueous solution.

Cation participation in nucleophilic substitution reactions promoted by complexes of polyether ligands with alkali and alkaline-earth metal salts

Cation electrophilic catalysis has been studied in nucleophilic substitution reactions of octyl methanesulfonate (1) promoted by complexes of macrocyclic polyethers 2–5 with alkali and alkaline-earth metal salts in chlorobenzene. The catalytic effect increases with increasing Lewis acid character of the cation, in the order Cs+∼ Rb+∼ K+ < Na+ < Li+ and Ba2+ < Sr2+ < Ca2+, and is mainly related to the ability of the polyether to shield the metal ion charge. Kinetic data clearly indicate that crown ethers 2-4 allow the metal ion participation in the activation process, whereas the cryptand [2.2.2,C10](5), which more effectively binds the cation, inhibits catalysis. The lower reactivity of the complexes of alkaline-earth metal salts with both crown ethers and cryptands is most likely due to a higher interaction of the divalent cation with the anion in the ion-pair.

Thermal dimerization of alkali and alkaline earth acrylate–but-3-enoate and methacrylate–but-3-enoate binary systems in the solid state

The solid state thermal reaction of binary salts obtained from a solution of an equimolar mixture of alkali or alkaline earth salts of but-3-enoic acid and methacrylic acid (3-BA–MA), after conversion to the methyl ester, gave mainly dimethyl (E)-hex-1-ene-1,5-dicarboxylate as a novel cross-coupled dimer. The highest conversion (62.2%) to the cross-coupled dimer was obtained using the potassium salts on heating at 230 °C for 2 h. Similarly, the methyl ester of the cross-coupled dimer, dimethyl (E)-pent-1-ene-1,5-dicarboxylate, was obtained from the salts of 3-BA and acrylic acid (AA), however a small amount on an isomeric ester dimethyl (E)-pent-2-ene-1, 5-dicarboxylate was also obtained. The X-ray diffraction patterns of potassium 3-BA–MA and potassium 3-BA–AA indicate the presence of a new phase, different from that of the individual salts. The selective cross-coupled dimerization, without rearrangement of 3-BA to crotonic acid, polymerization and crosslinking, was due to the new crystal phase of the binary salts as well as to the formation of solid solution crystals between the monomeric salts and the dimeric salt.

FTIR study on phase transitions in alkaline and alkaline earth metal salt solutions in acetonitrile

The phase transitions liquid → solid (β) and solid (β) → solid (α) are investigated for pure acetonitrile and acetonitrile solutions of alkaline and alkaline earth metal salts. The solutions of the alkaline earth metal perchlorates show no phase transition solid (β) → solid (σ), due to the geometry of the orthorombic unit cell of the solid α phase, requiring a coordination number of four upon the included cation.