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Reagent
In chemistry, a reagent ( ) or analytical reagent is a substance or compound added to a system to cause a chemical reaction, or test if one occurs. The terms ''reactant'' and ''reagent'' are often used interchangeably, but reactant specifies a substance ''consumed'' in the course of a chemical reaction. ''Solvents'', though involved in the reaction mechanism, are usually not called reactants. Similarly, ''catalysts'' are not consumed by the reaction, so they are not reactants. In biochemistry, especially in connection with enzyme-catalyzed reactions, the reactants are commonly called substrates. Definitions Organic chemistry In organic chemistry, the term "reagent" denotes a chemical ingredient (a compound or mixture, typically of inorganic or small organic molecules) introduced to cause the desired transformation of an organic substance. Examples include the Collins reagent, Fenton's reagent, and Grignard reagents. Analytical chemistry In analytical chemistry, a reagent ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Grignard Reagent
A Grignard reagent or Grignard compound is a chemical compound with the general formula , where X is a halogen and R is an organic functional group, group, normally an alkyl or aryl. Two typical examples are methylmagnesium chloride and phenylmagnesium bromide . They are a subclass of the organomagnesium compounds. Grignard compounds are popular reagents in organic synthesis for creating new carbon-carbon bonds. For example, when reacted with another halogenated compound in the presence of a suitable catalysis, catalyst, they typically yield and the magnesium halide as a byproduct; and the latter is insoluble in the solvents normally used. In this aspect, they are similar to organolithium reagents. Pure Grignard reagents are extremely reactive solids. They are normally handled as solutions in solvents such as diethyl ether or tetrahydrofuran; which are relatively stable as long as water is excluded. In such a medium, a Grignard reagent is invariably present as a coordinati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemical Purity
In chemistry, chemical purity is the measurement of the amount of impurities found in a sample. Several grades of purity are used by the scientific, pharmaceutical, and industrial communities. Some of the commonly used grades of purity include: * ACS grade is the highest level of purity, and meets the standards set by the American Chemical Society (ACS). The official descriptions of the ACS levels of purity is documented in the '' Reagent Chemicals'' publication, issued by the ACS. It is suitable for food and laboratory uses. * Reagent grade is almost as stringent as the ACS grade. * USP grade meets the purity levels set by the United States Pharmacopeia (USP). USP grade is equivalent to the ACS grade for many drugs. * NF grade is a purity grade set by the National Formulary (NF). NF grade is equivalent to the ACS grade for many drugs. * British Pharmacopoeia: Meets or exceeds requirements set by the British Pharmacopoeia The ''British Pharmacopoeia'' (''BP'') is th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fenton's Reagent
Fenton's reagent is a solution of hydrogen peroxide (H2O2) with ferrous iron (typically iron(II) sulfate, FeSO4) as a catalyst that is used to oxidize contaminants or waste waters as part of an advanced oxidation process. Fenton's reagent can be used to destroy organic compounds such as trichloroethylene (TCE) and tetrachloroethylene (perchloroethylene, PCE). It was developed in the 1890s by Henry John Horstman Fenton as an analytical reagent. Overview Iron(II) is oxidized by hydrogen peroxide to iron(III), forming a hydroxyl radical and a hydroxide ion in the process. Iron(III) is then reduced back to iron(II) by another molecule of hydrogen peroxide, forming a hydroperoxyl radical and a proton. The net effect is a disproportionation of hydrogen peroxide to create two different oxygen-radical species, with water (H+ + OH−) as a byproduct. The free radicals generated by this process then engage in secondary reactions. For example, the hydroxyl is a powerful, non- ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Millon's Reagent
Millon's reagent is an analytical reagent used to detect the presence of soluble proteins. A few drops of the reagent are added to the test solution, which is then heated gently. A reddish-brown coloration or precipitate indicates the presence of tyrosine residue which occur in nearly all proteins. The test was developed by the French chemist Auguste Nicolas Eugene Millon. The reagent is made by dissolving metallic mercury in nitric acid and diluting with water, forming mercuric nitrate (Hg O3sub>2). In the test, the phenol group in the side chain of tyrosine gets nitrated, and that product then complexes with Hg(I) or Hg(II) ions to give a red colored precipitate. Millon's test is not specific for proteins; it also gives a positive test for other compounds containing the phenol functional group. Therefore, the biuret test or the ninhydrin Ninhydrin (2,2-dihydroxyindane-1,3-dione) is an organic compound with the formula C6H4(CO)2C(OH)2. It is used to detect ammonia and amine ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
American Chemical Society
The American Chemical Society (ACS) is a scientific society based in the United States that supports scientific inquiry in the field of chemistry. Founded in 1876 at New York University, the ACS currently has more than 155,000 members at all degree levels and in all fields of chemistry, chemical engineering, and related fields. It is one of the world's largest scientific societies by membership. The ACS is a 501(c)(3) non-profit organization and holds a congressional charter under Title 36 of the United States Code. Its headquarters are located in Washington, D.C., and it has a large concentration of staff in Columbus, Ohio. The ACS is a leading source of scientific information through its peer-reviewed scientific journals, national conferences, and the Chemical Abstracts Service. Its publications division produces over 60 scholarly journals including the prestigious ''Journal of the American Chemical Society'', as well as the weekly trade magazine '' Chemical & Engineeri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Collins Reagent
Collins reagent is the complex of chromium(VI) oxide with pyridine in dichloromethane. This metal-pyridine complex, a red solid, is used to oxidize primary alcohols to the corresponding aldehydes and secondary alcohols to the corresponding ketones. This complex is a hygroscopic orange solid. Synthesis and structure The complex is produced by treating chromium trioxide with pyridine. The complex is diamagnetic. According to X-ray crystallography, the complex is 5-coordinate with mutually trans pyridine ligands. The Cr-O and Cr-N distances are respectively 163 and 215 picometers. In terms of history, the complex was first produced by Sisler et al. Reactions Collins reagent is especially useful for oxidations of acid sensitive compounds. Primary and secondary alcohols are oxidized respectively to aldehydes and ketones in yields of 87-98%. Like other oxidations by Cr(VI), the stoichiometry of the oxidations is complex because the metal undergoes 3e reduction and the substrate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antibody
An antibody (Ab), also known as an immunoglobulin (Ig), is a large, Y-shaped protein used by the immune system to identify and neutralize foreign objects such as pathogenic bacteria and Viral disease, viruses. The antibody recognizes a unique molecule of the pathogen, called an antigen. Each tip of the "Y" of an antibody contains a paratope (analogous to a lock) that is specific for one particular epitope (analogous to a key) on an antigen, allowing these two structures to bind together with precision. Using this binding mechanism, an antibody can ''tag'' a microbe or an infected cell for attack by other parts of the immune system, or can neutralize it directly (for example, by blocking a part of a virus that is essential for its invasion). To allow the immune system to recognize millions of different antigens, the antigen-binding sites at both tips of the antibody come in an equally wide variety. In contrast, the remainder of the antibody is relatively constant. It only occurs ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sodium
Sodium is a chemical element with the symbol Na (from Latin ''natrium'') and atomic number 11. It is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in group 1 of the periodic table. Its only stable isotope is 23Na. The free metal does not occur in nature, and must be prepared from compounds. Sodium is the sixth most abundant element in the Earth's crust and exists in numerous minerals such as feldspars, sodalite, and halite (NaCl). Many salts of sodium are highly water-soluble: sodium ions have been leached by the action of water from the Earth's minerals over eons, and thus sodium and chlorine are the most common dissolved elements by weight in the oceans. Sodium was first isolated by Humphry Davy in 1807 by the electrolysis of sodium hydroxide. Among many other useful sodium compounds, sodium hydroxide ( lye) is used in soap manufacture, and sodium chloride ( edible salt) is a de-icing agent and a nutrient for animals i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polyclonal Antibodies
Polyclonal antibodies (pAbs) are antibodies that are secreted by different B cell lineages within the body (whereas monoclonal antibodies come from a single cell lineage). They are a collection of immunoglobulin molecules that react against a specific antigen, each identifying a different epitope. Production The general procedure to produce polyclonal antibodies is as follows: # Antigen preparation # Adjuvant selection and preparation # Animal selection # Injection process # Blood serum extraction An antigen/adjuvant conjugate is injected into an animal of choice to initiate an amplified immune response. After a series of injections over a specific length of time, the animal is expected to have created antibodies against the conjugate. Blood is then extracted from the animal and then purified to obtain the antibody of interest. Inoculation is performed on a suitable mammal, such as a mouse, rabbit or goat. Larger mammals are often preferred as the amount of serum that can ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemical Reaction
A chemical reaction is a process that leads to the chemical transformation of one set of chemical substances to another. Classically, chemical reactions encompass changes that only involve the positions of electrons in the forming and breaking of chemical bonds between atoms, with no change to the nuclei (no change to the elements present), and can often be described by a chemical equation. Nuclear chemistry is a sub-discipline of chemistry that involves the chemical reactions of unstable and radioactive elements where both electronic and nuclear changes can occur. The substance (or substances) initially involved in a chemical reaction are called reactants or reagents. Chemical reactions are usually characterized by a chemical change, and they yield one or more products, which usually have properties different from the reactants. Reactions often consist of a sequence of individual sub-steps, the so-called elementary reactions, and the information on the precise co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Catalysis
Catalysis () is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst (). Catalysts are not consumed in the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recycles quickly, very small amounts of catalyst often suffice; mixing, surface area, and temperature are important factors in reaction rate. Catalysts generally react with one or more reactants to form intermediates that subsequently give the final reaction product, in the process of regenerating the catalyst. Catalysis may be classified as either homogeneous, whose components are dispersed in the same phase (usually gaseous or liquid) as the reactant, or heterogeneous, whose components are not in the same phase. Enzymes and other biocatalysts are often considered as a third category. Catalysis is ubiquitous in chemical industry of all kinds. Estimates are that 90% of all commercially produced chemical products involve catalysts at some st ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organic Chemistry
Organic chemistry is a subdiscipline within chemistry involving the science, scientific study of the structure, properties, and reactions of organic compounds and organic materials, i.e., matter in its various forms that contain carbon atoms.Clayden, J.; Greeves, N. and Warren, S. (2012) ''Organic Chemistry''. Oxford University Press. pp. 1–15. . Study of structure determines their structural formula. Study of properties includes Physical property, physical and Chemical property, chemical properties, and evaluation of Reactivity (chemistry), chemical reactivity to understand their behavior. The study of organic reactions includes the organic synthesis, chemical synthesis of natural products, drugs, and polymers, and study of individual organic molecules in the laboratory and via theoretical (in silico) study. The range of chemicals studied in organic chemistry includes hydrocarbons (compounds containing only carbon and hydrogen) as well as compounds based on carbon, but also con ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
