Chemie an starren Grenzflächen, 7 [1] Ausgewählte Beispiele der chemischen Grenzflächenmodifizierung von Aerosil / Chemistry at Rigid Surfaces, 7 [1] Selected Examples of the Chemical Surface Modification of Aerosil

1987 ◽  
Vol 42 (5) ◽  
pp. 643-660 ◽  
Author(s):  
Leopold Horner ◽  
Hans Ziegler
Keyword(s):  
Phosphoric Acid ◽  
Functional Groups ◽  
Carbonic Acid ◽  
Covalent Bond ◽  
Chemical Surface ◽  
Usual Manner ◽  
Primary Amino ◽  
Covalently Linked ◽  
Acid Anhydrides ◽  
Rigid Surfaces

Aminoaerosil containing primary amino end groups is obtained according (1) by reaction of aerosil with γ-triethoxysilylpropyl amine (Table II).The NH2-anchor groups are acylated in the usual manner: carbonic acid anhydrides, acid chlorides and acid azides and by application of the carbodiimide method (Table III). Optically active groups and phosphoric acid diestergroups are covalently linked with the surface of aerosil according (2) and (3). Aminoaerosil reacts with vinylsulfones as anchor groups of dyes (Remazol- Dyes) producing a covalent bond according (6).Functional groups linked to the surface of aerosil react “normal” (with respect to homogenous solutions) with group specific reagents. Examples: bromination, ozonization of C-C double bonds, hydrolysis of phosphoric acid esteramidates and surface bound chloroamine-T groups. "Interparticular" reactions of modified aerosil are not observed. But aerosil with electroactive groups are electroreduced using Hg- or Pb-electrodes.The optical induction of the catalytic hydrogenation of prochiral defines using palladium deposited on chiral modified aerosil surfaces is low (ca. 1%).Some analytical methods are presented, which are recommended for the determination of the amount of functional groups bound to the surface.

Aldehyde gold clusters for molecular labeling

1995 ◽  
Vol 53 ◽  
pp. 858-859
Author(s):  
James F. Hainfeld ◽  
Frederic R. Furuya
Keyword(s):  
Covalent Bond ◽  
Aldehyde Group ◽  
Gold Clusters ◽  
Side Reactions ◽  
Amino Groups ◽  
Sodium Cyanoborohydride ◽  
Schiff’S Base ◽  
Protein Molecules ◽  
Hydroxysuccinimide Esters ◽  
Primary Amino

Glutaraldehyde is a useful tissue and molecular fixing reagents. The aldehyde moiety reacts mainly with primary amino groups to form a Schiff's base, which is reversible but reasonably stable at pH 7; a stable covalent bond may be formed by reduction with, e.g., sodium cyanoborohydride (Fig. 1). The bifunctional glutaraldehyde, (CHO-(CH2)3-CHO), successfully stabilizes protein molecules due to generally plentiful amines on their surface; bovine serum albumin has 60; 59 lysines + 1 α-amino. With some enzymes, catalytic activity after fixing is preserved; with respect to antigens, glutaraldehyde treatment can compromise their recognition by antibodies in some cases. Complicating the chemistry somewhat are the reported side reactions, where glutaraldehyde reacts with other amino acid side chains, cysteine, histidine, and tyrosine. It has also been reported that glutaraldehyde can polymerize in aqueous solution. Newer crosslinkers have been found that are more specific for the amino group, such as the N-hydroxysuccinimide esters, and are commonly preferred for forming conjugates. However, most of these linkers hydrolyze in solution, so that the activity is lost over several hours, whereas the aldehyde group is stable in solution, and may have an advantage of overall efficiency.

Imine Based Self-Healing Hydrogel Triggered by Periodate

2020 ◽  
Author(s):  
Alexis Wolfel ◽  
Cecilia Inés Alvarez Igarzabal ◽  
Marcelo Ricardo Romero
Keyword(s):  
Functional Groups ◽  
Time Window ◽  
Crosslinking Reaction ◽  
Self Healing ◽  
Swelling Properties ◽  
Covalent Bonds ◽  
Smart Systems ◽  
Primary Amino ◽  
Vicinal Diols ◽  
Aldehyde Groups

<p>Design of materials with novel sensitivities and smart behaviour is important for the development of smart systems with automated responsiveness. We have recently reported the synthesis of hydrogels, cross-linked by <i>N,N'</i>-diallyltartardiamide (DAT). The covalent DAT-crosslinking points have vicinal diols which can be easily cleaved with periodate, generating valuable a-oxo-aldehyde functional groups, useful for further chemical modification. Based on those findings, we envisioned that a self-healable hydrogel could be obtained by incorporation of primary amino functional groups, from <a>2-aminoethyl methacrylate </a>hydrochloride (AEMA), coexisting with DAT into the same network. The a-oxo-aldehyde groups generated after the reaction with periodate would arise in the immediate environment of amine groups to form imine cross-links. For this purpose, DAT-crosslinked hydrogels were synthesized and carefully characterized. The cleavage of DAT-crosslinks with periodate promoted changes in the mechanical and swelling properties of the materials. As expected, a self-healing behavior was observed, based on the spontaneous formation of imine covalent bonds. In addition, we surprisingly found a combination of fast vicinal diols cleavage and a low speed self-crosslinking reaction by imine formation. Consequently, it was found a time-window in which a periodate-treated polymer was obtained in a transient liquid state, which can be exploited to choose the final shape of the material, before automated gelling. The singular properties attained on these hydrogels could be useful for developing sensors, actuators, among other smart systems.</p>

Sorption of Lead by the Selective Ion Exchanger Ostsorb DETA

1992 ◽  
Vol 57 (7) ◽  
pp. 1393-1404 ◽  
Author(s):  
Ladislav Svoboda ◽  
Jan Uhlíř ◽  
Zdeněk Uhlíř
Keyword(s):  
Phosphoric Acid ◽  
Aqueous Solutions ◽  
Functional Groups ◽  
Ion Exchanger ◽  
Preconcentration Procedure ◽  
Bead Cellulose

The properties of Ostsorb DETA, a selective ion exchanger based on modified bead cellulose with chemically bonded diethylenetriamine functional groups, were studied, and its applicability to the preconcentration of trace amounts of lead from aqueous solutions was verified. The conditions of the preconcentration procedure in the column and batch modes were optimized for this purpose. The results obtained were applied to the determination of lead in phosphoric acid.

On the Thermo-electric Properties of Solid and Liquid Mercury

1902 ◽  
Vol 23 ◽  
pp. 15-15 ◽  
Author(s):  
W. Peddie ◽  
A. B. Shand
Keyword(s):  
Carbonic Acid ◽  
Large Mass ◽  
Electric Properties ◽  
Considerable Time ◽  
Chemical Laboratory ◽  
Thermo Electric ◽  
Liquid Mercury ◽  
Usual Manner ◽  
Solid Form ◽  
The University

AbstractBy means of a large quantity of solid carbonic acid, obtained from the University Chemical Laboratory, it was found possible to solidify, and maintain in the solid form for a considerable time, a large mass of mercury. Preliminary experiments made about a year ago, in the usual manner, by means of a triple circuit (iron, german silver, mercury), did not give results of a satisfactory kind. This was apparently due to the difficulty of maintaining steady, or steadily varying, temperatures.

scholarly journals The impact of functional groups of the surface of carbon materials on the efficiency of purification of extraction phosphoric acid from fluorine compounds

2019 ◽  
Vol 2 ◽  
pp. 11-18
Author(s):  
Smirnov N.N. ◽  
Konoval A.V. ◽  
Smirnova D.N. ◽  
Kochetkov S.P.
Keyword(s):  
Phosphoric Acid ◽  
Functional Groups ◽  
Carbon Materials ◽  
Raw Materials ◽  
Carbon Adsorbents ◽  
Joint Stock Company ◽  
Stock Company ◽  
Fluorine Compounds ◽  
The Impact ◽  
Extraction Phosphoric Acid

The environmental problems of the production of extraction phosphoric acid and the effect of fluorine on the human body are discussed in the article. The creation of the industry of phosphoric fertilizers on the basis of processing of fluorine-containing phosphate raw materials and fluorine-containing compounds, the development of their application require the study of environmental consequences arising from this, because fluorine is characterized by high mobility in the biological cycle of metabolism. For the purification of phosphoric acid from fluorine was used carbon adsorbents such as active charcoal brand BAU, natural graphite deposits Kyshtymsky, P514 soot, charcoal. Experiments on the purification was carried out on non-evaporated half-hydrated extraction phosphoric acid which was produced by joint stock company «Apatit» in Cherepovets city in Russia. The following analyses were carried out: IR-Fourier spectrometry, research of acid–base properties of carbon materials by potentiometric titration, potentiometric method of fluorine determination in extraction phosphoric acid. It is mentioned that the carbon black P514 is the most efficient adsorbent for purification of extraction phosphoric acid. The total number of functional groups on its surface is 0.62 mmol/g, the degree of purification from fluorine compounds is 94.8%.

Flavin transferase: the maturation factor of flavin-containing oxidoreductases

2018 ◽  
Vol 46 (5) ◽  
pp. 1161-1169 ◽  
Author(s):  
Alexander V. Bogachev ◽  
Alexander A. Baykov ◽  
Yulia V. Bertsova
Keyword(s):  
Bond Formation ◽  
Covalent Bond ◽  
Target Protein ◽  
Covalent Attachment ◽  
Future Research ◽  
Post Translational Modification ◽  
Nadh:Quinone Oxidoreductase ◽  
Maturation Factor ◽  
Covalently Linked ◽  
Prevailing View

Flavins, cofactors of many enzymes, are often covalently linked to these enzymes; for instance, flavin adenine mononucleotide (FMN) can form a covalent bond through either its phosphate or isoalloxazine group. The prevailing view had long been that all types of covalent attachment of flavins occur as autocatalytic reactions; however, in 2013, the first flavin transferase was identified, which catalyzes phosphoester bond formation between FMN and Na+-translocating NADH:quinone oxidoreductase in certain bacteria. Later studies have indicated that this post-translational modification is widespread in prokaryotes and is even found in some eukaryotes. Flavin transferase can occur as a separate ∼40 kDa protein or as a domain within the target protein and recognizes a degenerate DgxtsAT/S motif in various target proteins. The purpose of this review was to summarize the progress already achieved by studies of the structure, mechanism, and specificity of flavin transferase and to encourage future research on this topic. Interestingly, the flavin transferase gene (apbE) is found in many bacteria that have no known target protein, suggesting the presence of yet unknown flavinylation targets.

Dundasite from North Wales

1906 ◽  
Vol 14 (65) ◽  
pp. 167-169 ◽  
Author(s):  
G. T. Prior
Keyword(s):  
Quantitative Analysis ◽  
Phosphoric Acid ◽  
Carbonic Acid ◽  
Thin Coating ◽  
Chemical Formula ◽  
Loss On Ignition ◽  
North Wales

The mineral dundasite was first described by W. F. Petterd in 1893, a ‘Catalogue of Minerals known to occur in Tasmania’. It was found in small, silky, milk-white, spherical aggregates incrusting a ‘ferro-manganese gossan’ at the Adelaide Proprietary mine, Dundas. In this catalogue, and in a subsequent one dated 1896, it was stated, as the result of qualitative tests, to be a hydrated carbono-phosphate of lead and aluminium ; but a quantitative analysis (see below under II), made later by S. Pascoe, showed that the mineral is a hydrated carbonate of lead and aluminium, and that the traces of phosphoric acid were due to a thin coating of pyromorphite. In this analysis the water and carbonic acid were determined together, by loss on ignition, and consequently hitherto no chemical formula has been attributed to the mineral.

Tailoring the structure of hybrid organic inorganic nanomaterials built on tetra- and polyfunctional alco-oxo-titanium clusters in polystyrene

2006 ◽  
Vol 39 (5) ◽  
pp. 656-660 ◽  
Author(s):  
Sondes Trabelsi ◽  
Giulia Fornasieri ◽  
Laurence Rozes ◽  
Andreas Janke ◽  
Axel Mensch ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Functional Groups ◽  
Three Dimensional ◽  
Hybrid Nanomaterials ◽  
Energy Filtering ◽  
Transmission Electron ◽  
Reactive Groups ◽  
Covalently Linked ◽  
Structural Levels

Functional titanium oxo-clusters Ti16O16(OEt)32−x(OPhCH=CH2)xwith different numbers of styrenic groups, wherex= 4 (tetra) andx= 16 (poly), have been synthesized and copolymerized with styrene. The resulting hybrid nanomaterials present three-dimensional networks in which the inorganic nano-fillers are covalently linked to the inorganic polymer. The influence of the number of functional groups borne by the oxo clusters on the structure of the resulting hybrid nanomaterials has been investigated by a combination of small-angle X-ray scattering, transmission electron microscopy and energy-filtering transmission electron microscopy. Compared with the tetra-functional clusters, the poly-functional clusters were better dispersed in the hybrid phase even at very high cluster content (between 5 and 10 wt%). Independently of the number of functional groups, three structural levels (i.e.largest, intermediate and primary clusters) have been revealed. The size of the aggregates has been found to be reduced by increasing the number of styrenic reactive groups.

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