Non-acidic Conditions Research Articles

Steel Slag in Acid Mine Drainage Treatment and Control

Steel slags are composed of calcium alumino-silicate oxides. Most slags have a sandy texture, but others have a silty texture and give a fine, powdery feel. Neutralization potentials of steel slags range from 45 to 78%, which make them candidates for neutralizing the acidity in acid mine drainage. Analysis of total metal content in Mingo Junction steel slab shows high concentrations of aluminum, chromium, iron, manganese, and titanium. Upon leaching this slag with water, the leachate had a pH of 11.7 and n alkalinity of 1,450 mg/L as CaCO{sub 3} equivalent. In general, steel slag yielded more alkalinity than equal weights of limestone (500 to 1,500 mg/L compared to 60 to 80 mg/L) during leaching studies. Leaching the slag with water and a weak sulfuric acid solution showed that the metals contained in the slag were not readily leachable since these metals were found at low concentrations in the leachate. When different amounts of slag were mixed with an acid-producing coal refuse and then leached with water, pH values of the leachate varied between 3.5 and 7.3. Slightly elevated levels of selenium, nickel, manganese, and possibly iron were found in leachates of refuse/slag mixtures compared to refuse alone. Due tomore » slag's high availability in some areas and low cost, steel slags show potential as an acid-neutralizing material for coal refuse and acid-producing spoils, and for treating acid mine drainage directly. If slag is to be used as an alkaline amendment, it must be added in sufficient quantities to ensure nonacid conditions now and in the future, since under acid conditions some metals may become available. Steel slag can also be used as a liming material for soils. The most promising use for steel slag is as a source of alkalinity to fresh waters that may subsequently encounter acid mine drainage, such as alkaline leach beds or limestone sand applications to headwater streams.« less

An improved synthesis of oligodeoxynucleotide N3'-->P5' phosphoramidates and their chimera using hindered phosphoramidite monomers and a novel handle for reverse phase purification.

Oligodeoxynucleotide N3'-->P5' phosphoramidates are promising candidates for antisense therapeutics, as well as for diagnostic applications. We recently reported a new method for the synthesis of these oligonucleotide analogs which makes use of a phosphoramidite amine-exchange reaction in the key coupling step. We report herein an improved set of monomers that utilize a more reactive, hindered phosphoramidite to produce optimal yields in a single coupling step followed by oxidation, thereby eliminating the need for the previously reported couple-oxidize-couple-oxidize approach. On the 10 micromol scale, the synthesis is performed using only 3.6 equivalents (equiv.) of monomer. An improved oxidation reagent consisting of hydrogen peroxide, water, pyridine and THF is also introduced. Reported here for the first time is the use of a reverse-phase purification methodology employing a ribonucleotide purification handle that is removed under non-acidic conditions, in contrast to the conventional dimethoxytrityl group. The synthesis and purification of uniformly modified N3'-->P5' phosphoramidate oligodeoxy-nucleotides, as well as their chimera containing phosphodiester and/or phosphorothioate linkages at predefined positions, using these new methodologies are included herein. The results of31P NMR studies that led to this improved amine-exchange methodology are also described.

The first synthesis of monoazaporphyrins bearing a nitrogen atom at the peripheral position

Abstract 2-Aza-3,7,8,12,13,17,18-heptaalkylporphyrins were synthesized by use of improved ‘3+1’ condensation under non-acidic conditions.

Vanadium(V) oxytrinitrate, VO(NO3)3. A powerful reagent for the nitration of aromatic compounds at room temperature under non-acidic conditions

Download options Please wait... Article information DOI https://doi.org/10.1039/A801771I Article type Paper Download Citation J. Chem. Soc., Perkin Trans. 1, 1998, 1589-1590 BibTex EndNote MEDLINE ProCite ReferenceManager RefWorks RIS Permissions Request permissions Vanadium(V) oxytrinitrate, VO(NO3)3. A powerful reagent for the nitration of aromatic compounds at room temperature under non-acidic conditions M. F. A. Dove, B. Manz, J. Montgomery, G. Pattenden and S. A. Wood, J. Chem. Soc., Perkin Trans. 1, 1998, 1589 DOI: 10.1039/A801771I To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page. If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given. If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page. Read more about how to correctly acknowledge RSC content. Search articles by author Michael F. A. Dove Berthold Manz John Montgomery Gerald Pattenden Simon A. Wood

Ion-Exchange Properties of Strontium Hydroxyapatite under Acidic Conditions

ABSTRACT The ion exchange of strontium hydroxyapatite (SrHAp) with Pb2+ has been investigated under acidic conditions at 293 K. The addition of various acids to the exchanging solution enhanced the exchange capacity in the order HC1 > HBr > HF > HNO3 > no acid, corresponding to the formation of halogen apatites with the former three acids or hydrogen phosphate with HNO3. Since the ion-exchange capacity of SrHAp under nonacidic conditions is higher than that of chlorapatite, the aforementioned observations can be attributed to the participation of the protons introduced by the acids.

Episodic Acidification of Small Streams in the Northeastern United States: Fish Mortality in Field Bioassays

In situ bioassays were performed as part of the Episodic Response Project, to evaluate the effects of episodic stream acidification on mortality of brook trout (Salvelinus fontinalis) and forage fish species. We report the results of 122 bioassays in 13 streams of the three study regions: the Adirondack mountains of New York, the Catskill mountains of New York, and the Northern Appalachian Plateau of Pennsylvania. Bioassays during acidic episodes had significantly higher mortality than did bioassays conducted under nonacidic conditions, but there was little difference in mortality rates in bioassays experiencing acidic episodes and those experiencing acidic conditions throughout the test period. Multiple logistic regression models were used to relate bioassay mortality rates to summary statistics of time‐varying stream chemistry (inorganic monomeric aluminum, calcium, pH, and dissolved organic carbon) estimated for the 20‐d bioassay periods. The large suite of candidate regressors also included biological, regional, and seasonal factors, as well as several statistics summarizing various features of aluminum exposure duration and magnitude. Regressor variable selection and model assessment were complicated by multicolinearity and overdispersion. For the target fish species, brook trout, bioassay mortality was most closely related to time‐weighted median inorganic aluminum. Median Ca and minimum pH offered additional explanatory power, as did stream‐specific aluminum responses. Due to high multicollinearity, the relative importance of different aluminum exposure duration and magnitude variables was difficult to assess, but these variables taken together added no significant explanatory power to models already containing median aluminum. Between 59 and 79% of the variation in brook trout mortality was explained by models employing between one and five regressors. Simpler models were developed for smaller sets of bioassays that tested slimy and mottled sculpin (Cottus cognatus and C. bairdi) as well as blacknose dace (Rhinichthys atratulus). For these forage species a single inorganic aluminum exposure variable successfully accounted for 86‐98% of the observed mortality. Even though field bioassays showed evidence of multiple toxicity factors, models results suggest that adequate mortality predictions can be obtained from a single index of inorganic Al concentrations during exposure periods.

An improved preparation of tris(ethylenedioxyboryl)methane, a reagent for the homologation of aldehydes and ketones

The preparation of tris(ethylenedioxyboryl)methane ( 2), the reagent for the only known homologation of aldehydes and ketones under non-acidic conditions, was improved by avoiding the difficult isolation of the intermediate tris(dimethoxyboryl)methane ( 1) and by direct crystallization of 2.

New one-step process for the synthesis of functionalized 1,6-dioxaspiro[4,5]decanes

β-Phenylsulfonyl dihydrofurans 1 were readily prepared by reduction of α-phenylsulfonyl-γ-lactones with DIBAL-H, followed by dehydration with MsCl-Et 3N. Dihydrofurans 1 were deprotonated with n-BuLi and the resulting α-lithiated carbanion reacted with a wide variety of electrophiles. Particularly interesting is its reaction with γ-lactones because affords 1,6-dioxaspiro[4,5]decanes in good yields in one-step procedure. This new method of synthesis of spiroketals, in non-acid conditions, is thermodynamically controlled and occurs with high stereoselectivity at C-4, C-5 and C-7, but not at C-2.

Ferrier Rearrangement under Nonacidic Conditions Based on Iodonium-Induced Rearrangements of Allylic n-Pentenyl Esters, n-Pentenyl Glycosides, and Phenyl Thioglycosides

Ferrier Rearrangement under Nonacidic Conditions Based on Iodonium-Induced Rearrangements of Allylic n-Pentenyl Esters, n-Pentenyl Glycosides, and Phenyl Thioglycosides

Influence of adsorption characteristics of silane on the hydrolytic stability of silane at the silica-matrix interface

To gain insight into which parameters control the hydrolytic stability of the silane multilayer at the silica-matrix interface, the effects of addition of hydrochloric acid to silane solution on the characteristics of silane adsorbed on to a colloidal silica surface were investigated using g.p.c. and CP/MAS 29Si n.m.r. The characteristics of the silane chemisorbed on the silica surface in the non-acidic conditions are different from those under acidic conditions. This is due to the fact that the silane molecular species chemisorbed on the silica surface differs when in non-acidic and acidic conditions: the monomer and dimer species are mainly chemisorbed on to the surface in non-acidic conditions; whereas, under acidic conditions, a tretramer of higher molecular weight is chemisorbed on the silica surface. In addition to the above investigations, the effects of the adsorption characteristics of silane on the hydrolytic stability of silane at the silica-matrix interface were studied by means of a tensile test. The hydrolytic stability of the silane is dependent upon the cohesion strength of the silane multilayer, particularly that between the chemisorbed and the physisorbed silane. The increased hydrolytic stability is afforded by means of species which have an increased potential for hydrogen bonding.

A simplified liquid chromatography assay for the quantitation of halofantrine and desbutylhalofantrine in plasma and identification of a degradation product of desbutylhalofantrine formed under alkaline conditions

The development of a new and simplified, validated LC assay for the quantitation of halofantrine and desbutylhalofantrine in plasma is described. The methodology employs an inexpensive, rapid and simple liquid-liquid extraction procedure in combination with previously reported chromatographic conditions. The method has been employed to study aspects of the pharmacokinetics of orally administered halofantrine in beagle dogs and some preliminary data are presented. During development of the extraction procedure, degradation of desbutylhalofantrine was observed under non-acidic conditions in the extraction solvent ( tert-butyl methyl ether) and we also report the structural elucidation of the breakdown product and the conditions required to avoid this degradation.

Transnitrosation by N-Aryl-N-nitrosoureas; NO-Carrying O-Nitrosoisourea.

Transfer of nitroso groups, so-called transnitrosation, from aromatic N-nitroso compounds such as N-nitrosoureas, N-nitrosamides and N-nitrosamines, to aromatic amines or ureas was observed under non-acidic conditions at room temperature. Sterically hindered 3, 3-dibenzyl-1-(4-tolyl)-1-nitrosourea (1a) rapidly nitrosates indoline, N-alkylanilines or 3-methyl-1-(4-tolyl)urea to give their N-nitroso derivatives. In the case of N, N-dimethylanilines, nitrosative demethylation occurs to give N-methyl-N-nitrosanilines. The transnitrosation is accelerated by electron-releasing groups on the nitroso acceptors, N-alkylanilines. The transnitrosation mechanism is considered to be as follows : N-nitrosourea (1) thermally decomposes to nitric oxide and ureidyl radical followed by formation of an O-nitrosoisourea intermediate (10), which acts as an NO-carrying agent and nitrosates anilines or ureas.

A Mild, Nonacidic Method for the Conversion of Carboxylic Esters into Oxazolines

Abstract Conversion of carboxylic esters directly into amide alcohols is facilitated by use of base. Combined with a nonacidic cyclization of the intermediate amide alcohol this method allows formation of oxazolines under nonacidic conditions directly from the carboxylic esters.

A new method for the synthesis of nitriles from amides under non-acidic conditions

Aryl carboxamides and other electron rich amides were converted to the respective nitriles in good yields by treatment with Ag 2O and C 2H 5I in benzene at reflux.

Benzimidazole ribonucleosides: Observation of an unexpected nitration when performing non-aqueous diazotizations with t-butyl nitrite

Mild, non-acidic conditions used in the non-aqueous diazotization of a 2-aminobenzimidazole nucleoside with t-butyl nitrite gave an unexpected 4-nitrobenzimidazol-2-one nucleoside which was not formed when primary alkyl nitrites were used. The isolated compounds were evaluated for activity against herpesviruses and for cytotoxicity against human foreskin fibroblast cells.

N-Pentenyl esters facilitate an oxidative alternative to the Ferrier rearrangement. An expeditious route to sucrose

Ferrier-type reactions can now be carried out under non-acidic conditions by treating 3-n-pentenoyl glycals with iodonium dicollidinium perchlorate whereupon the terminal double bond is chemoselectively activated to furnish an allylic oxo-carbenium ion which reacts at the anomeric position with monosaccharide alcohols to afford 2,3-unsaturated disaccharides in fairly good yields.

Enantiocontrolled syntheses of the cuparene sesquiterpenes, (−)-herbertene, (+)-β-cuparenone, (−)-debromoaplysin, and (−)-aplysin

Enantiocontrolled syntheses of the Cuparene sesquiterpenes, (−)-herbertene, (+)-cuparenone, (−)-debromoaplysin, and (−)-aplysin, have been achieved starting from the optically active tricyclic dienone by employing a Fischer indolization reaction under non-acidic conditions as the key step.

Lithium aluminum hydride reduction of N-aziridinylimines to hydrocarbons

The hydride reduction of ketone and aldehyde N-aziridinylimines is reported. Unlike most other hydrazone reductions, the reaction proceeds at room temperature under non-acidic conditions, providing an unusually mild carbonyl-to-methylene conversion.

A convenient method for removal of the t-butyl group from nucleoside bis(t-butyl) phosphates under non-acidic conditions

A new method for selective removal of the t-butyl group from 3′ - bis(t-butyl) phosphate esters of 5′-0-(4,4′-dimethoxytrityl)deoxyribo-nucleosides was developed by use of Me 3SiCl and Et 3N. Several unexpected properties of the t-butyl group were described.

The 31-kDa polypeptide is an essential subunit of the vacuolar ATPase in Saccharomyces cerevisiae.

The VMA4 gene encodes a 26.6-kDa hydrophilic polypeptide which exhibits 34% sequence identity with the E subunit of the vacuolar ATPase from bovine kidney microsomes. The chromosomal VMA4 gene was inactivated by a 171-base pair deletion followed by insertion of the URA3 gene within the coding sequence. Null vma4 haploid mutants are viable. However, their growth is considerably slowed down specially in non-acidic conditions; they are cold sensitive and thermo-sensitive, exhibit poor growth on glycerol medium, and do not accumulate in their vacuole the red pigment of ade2 strains. No bafilomycin-sensitive ATPase is detected in a vacuolar fraction. These properties shared by null mutants in the A, B, and C subunits of the vacuolar ATPase show that the VMA4 polypeptide is also an essential component of the vacuolar ATPase which has been conserved from yeast to mammals. The tightly linked VMA4 and MIP1 (encoding the mitochondrial DNA polymerase) genes are divergently transcribed from face-to-face promoters. About 250 base pairs upstream of the VMA4 gene, Homoll and RPG consensus for the binding of TUF (RAP/GRF1) protein are present, suggesting that the VMA4 gene belongs to this large family of genes involved in cellular growth and division whose transcription is regulated by the TUF protein.