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Amidicity
The amidicity scale is a computational method for calculating the strength of an amide bond in an organic compound on a linear scale. It is analogous to aromaticity. It is based on the computed enthalpy of hydrogenation when compared to the reference compounds dimethylacetamide and azaadamantane-2-one. If an amidicity value is close to 100%, then the compound has very good amidic character (and is perfect at 100%); if the value is close to, or below, 0%, then the compound has a lack of amidic character. The scale is not restricted to these values; compounds with weaker amide bonds than azaadamantane-2-one will have amidicities below 0%, while compounds with stronger amide bonds than dimethylacetamide will have amidicities of above 100%. If the amidicity value is altered during an acylation, then this will act as a key thermodynamic Thermodynamics is a branch of physics that deals with heat, work, and temperature, and their relation to energy, entropy, and the physical properties ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amide Bond
In organic chemistry, an amide, also known as an organic amide or a carboxamide, is a compound with the general formula , where R, R', and R″ represent organic groups or hydrogen atoms. The amide group is called a peptide bond when it is part of the main chain of a protein, and an isopeptide bond when it occurs in a side chain, such as in the amino acids asparagine and glutamine. It can be viewed as a derivative of a carboxylic acid () with the hydroxyl group () replaced by an amine group (); or, equivalently, an acyl (alkanoyl) group () joined to an amine group. Common examples of amides are acetamide (), benzamide (), and dimethylformamide (). Amides are qualified as primary, secondary, and tertiary according to whether the amine subgroup has the form , , or , where R and R' are groups other than hydrogen. The core of amides is called the amide group (specifically, carboxamide group). Amides are pervasive in nature and technology. Proteins and important plastics li ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computational Chemistry
Computational chemistry is a branch of chemistry that uses computer simulation to assist in solving chemical problems. It uses methods of theoretical chemistry, incorporated into computer programs, to calculate the structures and properties of molecules, groups of molecules, and solids. It is essential because, apart from relatively recent results concerning the hydrogen molecular ion (dihydrogen cation, see references therein for more details), the quantum many-body problem cannot be solved analytically, much less in closed form. While computational results normally complement the information obtained by chemical experiments, it can in some cases predict hitherto unobserved chemical phenomena. It is widely used in the design of new drugs and materials. Examples of such properties are structure (i.e., the expected positions of the constituent atoms), absolute and relative (interaction) energies, electronic charge density distributions, dipoles and higher multipole moments, vi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organic Compound
In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. The study of the properties, reactions, and syntheses of organic compounds comprise the discipline known as organic chemistry. For historical reasons, a few classes of carbon-containing compounds (e.g., carbonate salts and cyanide salts), along with a few other exceptions (e.g., carbon dioxide, hydrogen cyanide), are not classified as organic compounds and are considered inorganic. Other than those just named, little consensus exists among chemists on precisely which carbon-containing compounds are excluded, making any rigorous definition of an organic compound elusive. Although organic compounds make up only a small percentage of Earth's crust, they are of central importance because all known life is based on organic compounds. Living t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Enthalpy Of Hydrogenation
The standard enthalpy of reaction (denoted \Delta_ H^\ominus or \Delta H_^\ominus) for a chemical reaction is the difference between total reactant and total product molar enthalpies, calculated for substances in their standard states. This can in turn be used to predict the total chemical bond energy liberated or bound during reaction, as long as the enthalpy of mixing is also accounted for. For a generic chemical reaction :\nu_ \text + \nu_ \text ~+ ~... \rightarrow \nu_ \text + \nu_ \text ~+ ~... the standard enthalpy of reaction \Delta_ H^\ominus is related to the standard enthalpy of formation \Delta_ H^\ominus values of the reactants and products by the following equation: : \Delta_ H^\ominus = \sum_ \nu_p\Delta_ H_^ - \sum_ \nu_r\Delta_ H_^ In this equation, \nu_p and \nu_r are the stoichiometric coefficients of each product p and reactant r. The standard enthalpy of formation, which has been determined for a vast number of substances, is the change of enthalpy du ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dimethylacetamide
Dimethylacetamide (DMAc or DMA) is the organic compound with the formula CH3C(O)N(CH3)2. This colorless, water-miscible, high-boiling liquid is commonly used as a polar solvent in organic synthesis. DMA is miscible with most other solvents, although it is poorly soluble in aliphatic hydrocarbons. Synthesis and production DMA is prepared commercially by the reaction of dimethylamine with acetic anhydride or acetic acid. Dehydration of the salt of dimethylamine and acetic acid also furnishes this compound: : CH3CO2H·HN(CH3)2 → H2O + CH3CON(CH3)2 Dimethylacetamide can also be produced by the reaction of dimethylamine with methyl acetate. : The separation and purification of the product is carried out by multistage distillation in rectification columns. DMA is obtained with essentially quantitive (99%) yield referred to methyl acetate. Reactions and applications The chemical reactions of dimethylacetamide are typical of ''N'',''N''-disubstituted amides. Hydrolysis of the acyl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acylation
In chemistry, acylation (or alkanoylation) is the chemical reaction in which an acyl group () is added to a compound. The compound providing the acyl group is called the acylating agent. Because they form a strong electrophile when treated with some metal catalysts, acyl halides are commonly used as acylating agents. For example, Friedel–Crafts acylation uses acetyl chloride (ethanoyl chloride or ) as the agent and aluminum chloride () as a catalyst to add an ethanoyl ( acetyl) group to benzene: The mechanism of this reaction is electrophilic aromatic substitution. Acyl halides and acid anhydrides of carboxylic acids are also commonly used acylating agents. In some cases, active esters exhibit comparable reactivity. All react with amines to form amides and with alcohols to form esters by nucleophilic acyl substitution. Acylation can be used to prevent rearrangement reactions that would normally occur in alkylation. To do this an acylation reaction is performed, then the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thermodynamic
Thermodynamics is a branch of physics that deals with heat, work, and temperature, and their relation to energy, entropy, and the physical properties of matter and radiation. The behavior of these quantities is governed by the four laws of thermodynamics which convey a quantitative description using measurable macroscopic physical quantities, but may be explained in terms of microscopic constituents by statistical mechanics. Thermodynamics applies to a wide variety of topics in science and engineering, especially physical chemistry, biochemistry, chemical engineering and mechanical engineering, but also in other complex fields such as meteorology. Historically, thermodynamics developed out of a desire to increase the efficiency of early steam engines, particularly through the work of French physicist Sadi Carnot (1824) who believed that engine efficiency was the key that could help France win the Napoleonic Wars. Scots-Irish physicist Lord Kelvin was the first to formulate a co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computational Chemistry
Computational chemistry is a branch of chemistry that uses computer simulation to assist in solving chemical problems. It uses methods of theoretical chemistry, incorporated into computer programs, to calculate the structures and properties of molecules, groups of molecules, and solids. It is essential because, apart from relatively recent results concerning the hydrogen molecular ion (dihydrogen cation, see references therein for more details), the quantum many-body problem cannot be solved analytically, much less in closed form. While computational results normally complement the information obtained by chemical experiments, it can in some cases predict hitherto unobserved chemical phenomena. It is widely used in the design of new drugs and materials. Examples of such properties are structure (i.e., the expected positions of the constituent atoms), absolute and relative (interaction) energies, electronic charge density distributions, dipoles and higher multipole moments, vi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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