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Section: Structure > Notation variants. The standard notation for chemical equations only permits all reactants on one side, all products on the other, and all stoichiometric coefficients positive. For example, the usual form of the equation for dehydration of methanol to dimethylether is: 2 CH3OH → CH3OCH3 + H2O Somet... | Wikipedia - Chemical equation - Structure > Notation variants | 319 | 1,414 | null |
Section: Balancing chemical equations. Because no nuclear reactions take place in a chemical reaction, the chemical elements pass through the reaction unchanged. Thus, each side of the chemical equation must represent the same number of atoms of any particular element (or nuclide, if different isotopes are taken into a... | Wikipedia - Chemical equation - Balancing chemical equations | 330 | 1,477 | null |
Section: Balancing chemical equations > Inspection method. The method of inspection can be outlined as setting the most complex substance's stoichiometric coefficient to 1 and assigning values to other coefficients step by step such that both sides of the equation end up with the same number of atoms for each element. ... | Wikipedia - Chemical equation - Balancing chemical equations > Inspection method | 347 | 1,138 | null |
The left-hand side also has 4 hydrogen atoms, which will be balanced by 2 molecules of H2O: 1 CH 4 + ? O 2 ⟶ 1 CO 2 + 2 H 2 O {\displaystyle {\ce {1{CH4}+{\mathord {?}}\,{O2}->1{CO2}+2H2O}}} Balancing the 4 oxygen atoms of the right-hand side by 2 molecules of O2 yields the equation 1 CH 4 + 2 O 2 ⟶ 1 CO 2 + 2 H 2 O {\... | Wikipedia - Chemical equation - Balancing chemical equations > Inspection method | 251 | 728 | null |
Section: Balancing chemical equations > System of linear equations. For each chemical element (or nuclide or unchanged moiety or charge) i, its conservation requirement can be expressed by the mathematical equation ∑ j ∈ reactants a i j s j = ∑ j ∈ products a i j s j {\displaystyle \sum _{j\,\in \,{\text{reactants}}}\!... | Wikipedia - Chemical equation - Balancing chemical equations > System of linear equations | 293 | 1,065 | null |
Let us assign variables to stoichiometric coefficients of the chemical equation from the previous section and write the corresponding linear equations: s 1 CH 4 + s 2 O 2 ⟶ s 3 CO 2 + s 4 H 2 O {\displaystyle {\ce {{\mathit {s}}_{1}{CH4}+{\mathit {s}}_{2}{O2}->{\mathit {s}}_{3}{CO2}+{\mathit {s}}_{4}{H2O}}}} C: s 1 = s... | Wikipedia - Chemical equation - Balancing chemical equations > System of linear equations > Example | 301 | 665 | null |
{\begin{aligned}s_{1}&=r\\s_{2}&=2r\\s_{3}&=r\\s_{4}&=2r\end{aligned}}} The choice of r = 1 yields the preferred solution, s 1 = 1 s 2 = 2 s 3 = 1 s 4 = 2 {\displaystyle {\begin{aligned}s_{1}&=1\\s_{2}&=2\\s_{3}&=1\\s_{4}&=2\end{aligned}}} which corresponds to the balanced chemical equation: CH 4 + 2 O 2 ⟶ CO 2 + 2 H 2... | Wikipedia - Chemical equation - Balancing chemical equations > System of linear equations > Example | 183 | 372 | null |
Section: Balancing chemical equations > Matrix method. The system of linear equations introduced in the previous section can also be written using an efficient matrix formalism. First, to unify the reactant and product stoichiometric coefficients sj, let us introduce the quantity ν j = { − s j for a reactant + s j for ... | Wikipedia - Chemical equation - Balancing chemical equations > Matrix method | 207 | 685 | null |
First, to unify the reactant and product stoichiometric coefficients sj, let us introduce the quantity ν j = { − s j for a reactant + s j for a product {\displaystyle \nu _{j}={\begin{cases}-s_{j}&{\text{for a reactant}}\\+s_{j}&{\text{for a product}}\end{cases}}} called stoichiometric number, which simplifies the line... | Wikipedia - Chemical equation - Balancing chemical equations > Matrix method | 445 | 1,185 | null |
Placement of the values aij at row i and column j of the composition matrix A = [ a 1 , 1 a 1 , 2 ⋯ a 1 , J a 2 , 1 a 2 , 2 ⋯ a 2 , J ⋮ ⋮ ⋱ ⋮ ] {\displaystyle {\begin{bmatrix}a_{1,1}&a_{1,2}&\cdots &a_{1,J}\\a_{2,1}&a_{2,2}&\cdots &a_{2,J}\\\vdots &\vdots &\ddots &\vdots \end{bmatrix}}} and arrangement of the stoichiom... | Wikipedia - Chemical equation - Balancing chemical equations > Matrix method | 349 | 1,069 | null |
Example Using the same chemical equation again, write the corresponding matrix equation: s 1 CH 4 + s 2 O 2 ⟶ s 3 CO 2 + s 4 H 2 O {\displaystyle {\ce {{\mathit {s}}_{1}{CH4}+{\mathit {s}}_{2}{O2}->{\mathit {s}}_{3}{CO2}+{\mathit {s}}_{4}{H2O}}}} C: H: O: [ 1 0 1 0 4 0 0 2 0 2 2 1 ] [ ν 1 ν 2 ν 3 ν 4 ] = 0 {\displaysty... | Wikipedia - Chemical equation - Balancing chemical equations > Matrix method | 349 | 701 | null |
_{1}\\\nu _{2}\\\nu _{3}\\\nu _{4}\end{bmatrix}}={\begin{bmatrix}-s_{1}\\-s_{2}\\s_{3}\\s_{4}\end{bmatrix}}=r{\begin{bmatrix}-1\\-2\\1\\2\end{bmatrix}}} The choice of r = 1 and a sign-flip of the first two rows yields the preferred solution to the balancing problem: [ − ν 1 − ν 2 ν 3 ν 4 ] = [ s 1 s 2 s 3 s 4 ] = [ 1 2... | Wikipedia - Chemical equation - Balancing chemical equations > Matrix method | 290 | 511 | null |
For example, in the following precipitation reaction: CaCl 2 + 2 AgNO 3 ⟶ Ca ( NO 3 ) 2 + 2 AgCl ↓ {\displaystyle {\ce {CaCl2 + 2AgNO3 -> Ca(NO3)2 + 2 AgCl(v)}}} the full ionic equation is: Ca 2 + + 2 Cl − + 2 Ag + + 2 NO 3 − ⟶ Ca 2 + + 2 NO 3 − + 2 AgCl ↓ {\displaystyle {\ce {Ca^2+ + 2Cl^- + 2Ag+ + 2NO3^- -> Ca^2+ + 2... | Wikipedia - Chemical equation - Ionic equations | 349 | 882 | null |
Because such ions do not participate in the reaction, they are called spectator ions. A net ionic equation is the full ionic equation from which the spectator ions have been removed. The net ionic equation of the proceeding reactions is: 2 Cl − + 2 Ag + ⟶ 2 AgCl ↓ {\displaystyle {\ce {2Cl^- + 2Ag+ -> 2AgCl(v)}}} or, in... | Wikipedia - Chemical equation - Ionic equations | 278 | 955 | null |
In this reaction, there are no spectator ions, so the net ionic equation is the same as the full ionic equation. 3 Ba ( OH ) 2 + 2 H 3 PO 4 ⟶ 6 H 2 O + Ba 3 ( PO 4 ) 2 ↓ {\displaystyle {\ce {3Ba(OH)2 + 2H3PO4 -> 6H2O + Ba3(PO4)2(v)}}} 3 Ba 2 + + 6 OH − + 6 H + + 2 PO 4 3 − ⏟ phosphate ⟶ 6 H 2 O + Ba 3 ( PO 4 ) 2 ↓ ⏟ ba... | Wikipedia - Chemical equation - Ionic equations | 345 | 849 | null |
3 Ba ( OH ) 2 + 2 H 3 PO 4 ⟶ 6 H 2 O + Ba 3 ( PO 4 ) 2 ↓ {\displaystyle {\ce {3Ba(OH)2 + 2H3PO4 -> 6H2O + Ba3(PO4)2(v)}}} 3 Ba 2 + + 6 OH − + 6 H + + 2 PO 4 3 − ⏟ phosphate ⟶ 6 H 2 O + Ba 3 ( PO 4 ) 2 ↓ ⏟ barium phosphate {\displaystyle {\ce {{3Ba^{2}+}+{6OH^{-}}+{6H+}}}+\underbrace {\ce {2PO4^{3}-}} _{\ce {phosphate}}... | Wikipedia - Chemical equation - Ionic equations | 401 | 984 | null |
Generally, if zj is the multiple of elementary charge on the j-th molecule, charge neutrality may be written as: ∑ j = 1 J z j ν j = 0 {\displaystyle \sum _{j=1}^{J}z_{j}\nu _{j}=0} where the νj are the stoichiometric coefficients described above. The zj may be incorporated as an additional row in the aij matrix descri... | Wikipedia - Chemical equation - Ionic equations | 152 | 462 | null |
Article: Chemical free. Chemical free is a term used in marketing to imply that a product is safe, healthy or environmentally friendly because it only contains natural ingredients. The term is a misnomer, as all substances and objects are composed entirely of chemicals and energy. The term chemical is roughly a synonym... | Wikipedia - Chemical free - Summary | 196 | 1,004 | null |
Section: Purpose. In drug discovery high-throughput screening, it is desirable to screen a drug target against a selection of chemicals that try to take advantage of as much of the appropriate chemical space as possible. The chemical space of all possible chemical structures is extraordinarily large. Most stored chemic... | Wikipedia - Chemical library - Purpose | 176 | 938 | null |
Section: Generation of chemical libraries. Chemical libraries are usually generated for a specific goal and larger chemical libraries could be made of several groups of smaller libraries stored in the same location. In the drug discovery process for instance, a wide range of organic chemicals are needed to test against... | Wikipedia - Chemical library - Generation of chemical libraries | 281 | 1,532 | null |
Section: Design and optimization of chemical libraries. Chemical libraries are usually designed by chemists and chemoinformatics scientists and synthesized by organic chemistry and medicinal chemistry. The method of chemical library generation usually depends on the project and there are many factors to consider when u... | Wikipedia - Chemical library - Design and optimization of chemical libraries | 259 | 1,443 | null |
Section: Storage and management. The "chemical space" of all possible organic chemicals is large and increases exponentially with the size of the molecule. Most chemical libraries do not typically have a fully represented chemical space mostly because of storage and cost concerns. Because of the expense and effort invo... | Wikipedia - Chemical library - Storage and management | 239 | 1,358 | null |
Article: Chemical reaction. A chemical reaction is a process that leads to the chemical transformation of one set of chemical substances to another. When chemical reactions occur, the atoms are rearranged and the reaction is accompanied by an energy change as new products are generated. Classically, chemical reactions ... | Wikipedia - Chemical reaction - Summary | 347 | 1,988 | null |
A reaction may be classified as redox in which oxidation and reduction occur or non-redox in which there is no oxidation and reduction occurring. Most simple redox reactions may be classified as a combination, decomposition, or single displacement reaction. Different chemical reactions are used during chemical synthesi... | Wikipedia - Chemical reaction - Summary | 175 | 1,024 | null |
Section: History. Chemical reactions such as combustion in fire, fermentation and the reduction of ores to metals were known since antiquity. Initial theories of transformation of materials were developed by Greek philosophers, such as the Four-Element Theory of Empedocles stating that any substance is composed of the ... | Wikipedia - Chemical reaction - History | 342 | 1,782 | null |
From the 16th century, researchers including Jan Baptist van Helmont, Robert Boyle, and Isaac Newton tried to establish theories of experimentally observed chemical transformations. The phlogiston theory was proposed in 1667 by Johann Joachim Becher. It postulated the existence of a fire-like element called "phlogiston... | Wikipedia - Chemical reaction - History | 277 | 1,488 | null |
Section: Equations. Chemical equations are used to graphically illustrate chemical reactions. They consist of chemical or structural formulas of the reactants on the left and those of the products on the right. They are separated by an arrow (→) which indicates the direction and type of the reaction; the arrow is read ... | Wikipedia - Chemical reaction - Equations | 307 | 1,509 | null |
Section: Elementary reactions. The elementary reaction is the smallest division into which a chemical reaction can be decomposed, it has no intermediate products. Most experimentally observed reactions are built up from many elementary reactions that occur in parallel or sequentially. The actual sequence of the individ... | Wikipedia - Chemical reaction - Elementary reactions | 349 | 1,669 | null |
AB ⟶ A + B {\displaystyle {\ce {AB -> A + B}}} Dissociation of a molecule AB into fragments A and B For bimolecular reactions, two molecules collide and react with each other. Their merger is called chemical synthesis or an addition reaction. A + B ⟶ AB {\displaystyle {\ce {A + B -> AB}}} Another possibility is that on... | Wikipedia - Chemical reaction - Elementary reactions | 222 | 777 | null |
Section: Chemical equilibrium. Most chemical reactions are reversible; that is, they can and do run in both directions. The forward and reverse reactions are competing with each other and differ in reaction rates. These rates depend on the concentration and therefore change with the time of the reaction: the reverse ra... | Wikipedia - Chemical reaction - Chemical equilibrium | 214 | 1,172 | null |
Section: Thermodynamics. Chemical reactions are determined by the laws of thermodynamics. Reactions can proceed by themselves if they are exergonic, that is if they release free energy. The associated free energy change of the reaction is composed of the changes of two different thermodynamic quantities, enthalpy and e... | Wikipedia - Chemical reaction - Thermodynamics | 275 | 1,238 | null |
On the contrary, many exothermic reactions such as crystallization occur preferably at lower temperatures. A change in temperature can sometimes reverse the sign of the enthalpy of a reaction, as for the carbon monoxide reduction of molybdenum dioxide: 2 CO ( g ) + MoO 2 ( s ) ⟶ 2 CO 2 ( g ) + Mo ( s ) {\displaystyle {... | Wikipedia - Chemical reaction - Thermodynamics | 343 | 1,192 | null |
Section: Kinetics. The speed at which reactions take place is studied by reaction kinetics. The rate depends on various parameters, such as: Reactant concentrations, which usually make the reaction happen at a faster rate if raised through increased collisions per unit of time. Some reactions, however, have rates that ... | Wikipedia - Chemical reaction - Kinetics | 335 | 1,876 | null |
Several theories allow calculating the reaction rates at the molecular level. This field is referred to as reaction dynamics. The rate v of a first-order reaction, which could be the disintegration of a substance A, is given by: v = − d [ A ] d t = k ⋅ [ A ] . {\displaystyle v=-{\frac {d[{\ce {A}}]}{dt}}=k\cdot [{\ce {... | Wikipedia - Chemical reaction - Kinetics | 338 | 1,093 | null |
Section: Reaction types > Four basic types > Synthesis. In a synthesis reaction, two or more simple substances combine to form a more complex substance. These reactions are in the general form: A + B ⟶ AB {\displaystyle {\ce {A + B->AB}}} Two or more reactants yielding one product is another way to identify a synthesis... | Wikipedia - Chemical reaction - Reaction types > Four basic types > Synthesis | 150 | 611 | null |
Section: Reaction types > Four basic types > Single displacement. In a single displacement reaction, a single uncombined element replaces another in a compound; in other words, one element trades places with another element in a compound. These reactions come in the general form of: A + BC ⟶ AC + B {\displaystyle {\ce ... | Wikipedia - Chemical reaction - Reaction types > Four basic types > Single displacement | 154 | 574 | null |
Section: Reaction types > Four basic types > Double displacement. In a double displacement reaction, the anions and cations of two compounds switch places and form two entirely different compounds. These reactions are in the general form: AB + CD ⟶ AD + CB {\displaystyle {\ce {AB + CD->AD + CB}}} For example, when bari... | Wikipedia - Chemical reaction - Reaction types > Four basic types > Double displacement | 207 | 719 | null |
Section: Reaction types > Forward and backward reactions > Forward reactions. Reactions that proceed in the forward direction (from left to right) to approach equilibrium are often called spontaneous reactions, that is, Δ G {\displaystyle \Delta G} is negative, which means that if they occur at constant temperature and... | Wikipedia - Chemical reaction - Reaction types > Forward and backward reactions > Forward reactions | 159 | 723 | null |
Section: Reaction types > Combustion. In a combustion reaction, an element or compound reacts with an oxidant, usually oxygen, often producing energy in the form of heat or light. Combustion reactions frequently involve a hydrocarbon. For instance, the combustion of 1 mole (114 g) of octane in oxygen C 8 H 18 ( l ) + 2... | Wikipedia - Chemical reaction - Reaction types > Combustion | 237 | 685 | null |
Section: Reaction types > Oxidation and reduction. Redox reactions can be understood in terms of the transfer of electrons from one involved species (reducing agent) to another (oxidizing agent). In this process, the former species is oxidized and the latter is reduced. Though sufficient for many purposes, these descri... | Wikipedia - Chemical reaction - Reaction types > Oxidation and reduction | 337 | 1,450 | null |
Because the chlorine is the one reduced, it is considered the electron acceptor, or in other words, induces oxidation in the sodium – thus the chlorine gas is considered the oxidizing agent. Conversely, the sodium is oxidized or is the electron donor, and thus induces a reduction in the other species and is considered ... | Wikipedia - Chemical reaction - Reaction types > Oxidation and reduction | 346 | 1,665 | null |
Section: Reaction types > Complexation. In complexation reactions, several ligands react with a metal atom to form a coordination complex. This is achieved by providing lone pairs of the ligand into empty orbitals of the metal atom and forming dipolar bonds. The ligands are Lewis bases, they can be both ions and neutra... | Wikipedia - Chemical reaction - Reaction types > Complexation | 170 | 877 | null |
Section: Reaction types > Acid–base reactions. In the Brønsted–Lowry acid–base theory, an acid–base reaction involves a transfer of protons (H+) from one species (the acid) to another (the base). When a proton is removed from an acid, the resulting species is termed that acid's conjugate base. When the proton is accept... | Wikipedia - Chemical reaction - Reaction types > Acid–base reactions | 314 | 1,182 | null |
Section: Reaction types > Photochemical reactions. In photochemical reactions, atoms and molecules absorb energy (photons) of the illumination light and convert it into an excited state. They can then release this energy by breaking chemical bonds, thereby producing radicals. Photochemical reactions include hydrogen–ox... | Wikipedia - Chemical reaction - Reaction types > Photochemical reactions | 186 | 975 | null |
Section: Catalysis. In catalysis, the reaction does not proceed directly, but through a reaction with a third substance known as catalyst. Although the catalyst takes part in the reaction, forming weak bonds with reactants or intermediates, it is returned to its original state by the end of the reaction and so is not c... | Wikipedia - Chemical reaction - Catalysis | 346 | 1,683 | null |
Section: Reactions in organic chemistry. In organic chemistry, in addition to oxidation, reduction or acid-base reactions, a number of other reactions can take place which involves covalent bonds between carbon atoms or carbon and heteroatoms (such as oxygen, nitrogen, halogens, etc.). Many specific reactions in organi... | Wikipedia - Chemical reaction - Reactions in organic chemistry | 154 | 811 | null |
Section: Reactions in organic chemistry > Substitution. In a substitution reaction, a functional group in a particular chemical compound is replaced by another group. These reactions can be distinguished by the type of substituting species into a nucleophilic, electrophilic or radical substitution. In the first type, a... | Wikipedia - Chemical reaction - Reactions in organic chemistry > Substitution | 349 | 1,599 | null |
In the SN2 mechanisms, the nucleophile forms a transition state with the attacked molecule, and only then the leaving group is cleaved. These two mechanisms differ in the stereochemistry of the products. SN1 leads to the non-stereospecific addition and does not result in a chiral center, but rather in a set of geometri... | Wikipedia - Chemical reaction - Reactions in organic chemistry > Substitution | 344 | 1,591 | null |
Section: Reactions in organic chemistry > Addition and elimination. The addition and its counterpart, the elimination, are reactions that change the number of substituents on the carbon atom, and form or cleave multiple bonds. Double and triple bonds can be produced by eliminating a suitable leaving group. Similar to t... | Wikipedia - Chemical reaction - Reactions in organic chemistry > Addition and elimination | 327 | 1,673 | null |
Similar to substitution reactions, there are several types of additions distinguished by the type of the attacking particle. For example, in the electrophilic addition of hydrogen bromide, an electrophile (proton) attacks the double bond forming a carbocation, which then reacts with the nucleophile (bromine). The carbo... | Wikipedia - Chemical reaction - Reactions in organic chemistry > Addition and elimination | 337 | 1,548 | null |
This process is often associated with elimination so that after the reaction the carbonyl group is present again. It is, therefore, called an addition-elimination reaction and may occur in carboxylic acid derivatives such as chlorides, esters or anhydrides. This reaction is often catalyzed by acids or bases, where the ... | Wikipedia - Chemical reaction - Reactions in organic chemistry > Addition and elimination | 234 | 1,056 | null |
Section: Reactions in organic chemistry > Other organic reaction mechanisms. In a rearrangement reaction, the carbon skeleton of a molecule is rearranged to give a structural isomer of the original molecule. These include hydride shift reactions such as the Wagner-Meerwein rearrangement, where a hydrogen, alkyl or aryl... | Wikipedia - Chemical reaction - Reactions in organic chemistry > Other organic reaction mechanisms | 332 | 1,473 | null |
Section: Biochemical reactions. Biochemical reactions are mainly controlled by complex proteins called enzymes, which are usually specialized to catalyze only a single, specific reaction. The reaction takes place in the active site, a small part of the enzyme which is usually found in a cleft or pocket lined by amino a... | Wikipedia - Chemical reaction - Biochemical reactions | 279 | 1,441 | null |
Section: Applications. Chemical reactions are central to chemical engineering, where they are used for the synthesis of new compounds from natural raw materials such as petroleum, mineral ores, and oxygen in air. It is essential to make the reaction as efficient as possible, maximizing the yield and minimizing the numb... | Wikipedia - Chemical reaction - Applications | 165 | 833 | null |
Article: Chemical similarity. Chemical similarity (or molecular similarity) refers to the similarity of chemical elements, molecules or chemical compounds with respect to either structural or functional qualities, i.e. the effect that the chemical compound has on reaction partners in inorganic or biological settings. B... | Wikipedia - Chemical similarity - Summary | 192 | 1,104 | null |
Section: Similarity search and virtual screening. The similarity-based virtual screening (a kind of ligand-based virtual screening) assumes that all compounds in a database that are similar to a query compound have similar biological activity. Although this hypothesis is not always valid, quite often the set of retriev... | Wikipedia - Chemical similarity - Similarity search and virtual screening | 283 | 1,491 | null |
Section: Overview. The chemical state set comprises and encompasses these subordinate groups and entities: chemical species, functional group, anion, cation, oxidation state, chemical compound and elemental forms of an element. This term or phrase is commonly used when interpreting data from analytical techniques such ... | Wikipedia - Chemical state - Overview | 201 | 779 | null |
Section: Significance. The chemical state of a group of elements, can be similar to, but not identical to, the chemical state of another similar group of elements because the two groups have different ratios of the same elements and exhibit different chemical, electronic, and physical properties that can be detected by... | Wikipedia - Chemical state - Significance | 345 | 1,634 | null |
Section: Closely related nomenclature. The chemical state of an element is often confused with its oxidation state. The chemical state of an element or a group of elements that has a non-zero ionic charge, e.g. (1+), (2+), (3+), (1-), (2-) (3-), is defined as the oxidation state of that element or group of elements. El... | Wikipedia - Chemical state - Closely related nomenclature | 296 | 1,430 | null |
Article: Chemical synthesis. Chemical synthesis (chemical combination) is the artificial execution of chemical reactions to obtain one or several products. This occurs by physical and chemical manipulations usually involving one or more reactions. In modern laboratory uses, the process is reproducible and reliable. A c... | Wikipedia - Chemical synthesis - Summary | 224 | 1,194 | null |
Section: Strategies. Chemical synthesis employs various strategies to achieve efficient, precise, and molecular transformations that are more complex than simply converting a reactant A to a reaction product B directly. These strategies can be grouped into approaches for managing reaction sequences. Reaction Sequences:... | Wikipedia - Chemical synthesis - Strategies | 339 | 2,055 | null |
Section: Applications. Chemical synthesis plays a crucial role across various industries, enabling the development of materials, medicines, and technologies with significant real-world impacts. Catalysis: The development of catalysts is vital for numerous industrial processes, including petroleum refining, petrochemica... | Wikipedia - Chemical synthesis - Applications | 223 | 1,297 | null |
Section: Technologists. Chemical technologists are more likely than technicians to participate in the actual design of experiments, and may be involved in the interpretation of experimental data. They may also be responsible for the operation of chemical processes in large plants, and may even assist chemical engineers... | Wikipedia - Chemical technologist - Technologists | 164 | 906 | null |
Section: Definition and uses. There are differing opinions on the proper usage of the word chemophobia. The International Union of Pure and Applied Chemistry (IUPAC) defines chemophobia as an "irrational fear of chemicals". According to the American Council on Science and Health, chemophobia is a fear of synthetic subs... | Wikipedia - Chemophobia - Definition and uses | 327 | 1,642 | null |
Consequently, people fear man-made or "unnatural" chemicals, while accepting natural chemicals that are known to be dangerous or poisonous. The Carcinogenic Potency Project, which is a part of the US EPA's Distributed Structure-Searchable Toxicity (DSSTox) Database Network, has been systemically testing the carcinogeni... | Wikipedia - Chemophobia - Definition and uses | 314 | 1,617 | null |
Thus, we estimate that 99.99% of the pesticides humans ingest are natural. Despite this enormously greater exposure to natural chemicals, 79% (378 out of 479) of the chemicals tested for carcinogenicity in both rats and mice are synthetic (that is, do not occur naturally). 2) It has often been wrongly assumed that huma... | Wikipedia - Chemophobia - Definition and uses | 298 | 1,474 | null |
Section: Causes and effects. According to chemistry professor Pierre Laszlo, chemists have experienced chemophobia from the population at large, and asserts that it is rooted both in irrational notions and in genuine concerns (such as those over chemical warfare and industrial disasters). Gordon Gribble has written tha... | Wikipedia - Chemophobia - Causes and effects | 337 | 1,713 | null |
Elsewhere, Entine has argued that chemophobia is linked to a precautionary principle in agricultural policy, which could jeopardize the world's ability to feed its ever-expanding population. In the United Kingdom, Sense about Science produced a leaflet aimed at educating celebrities about science, in which it said that... | Wikipedia - Chemophobia - Causes and effects | 274 | 1,363 | null |
Article: Chemoproteomics. Chemoproteomics (also known as chemical proteomics) entails a broad array of techniques used to identify and interrogate protein-small molecule interactions. Chemoproteomics complements phenotypic drug discovery, a paradigm that aims to discover lead compounds on the basis of alleviating a dis... | Wikipedia - Chemoproteomics - Summary | 333 | 1,600 | null |
Section: Background > Context. The conclusion of the Human Genome Project was followed with hope for a new paradigm in treating disease. Many fatal and intractable diseases were able to be mapped to specific genes, providing a starting point to better understand the roles of their protein products in illness. Drug disc... | Wikipedia - Chemoproteomics - Background > Context | 276 | 1,471 | null |
Section: Background > Basic tools. The chemoproteomic toolkit is anchored by liquid chromatography-tandem mass spectrometry (LC-MS/MS or LC-MS) based quantitative proteomics, which allows for the near complete identification and relative quantification of complex proteomes in biological samples. In addition to proteomi... | Wikipedia - Chemoproteomics - Background > Basic tools | 298 | 1,275 | null |
Section: Solution-based approaches. Broad proteomic and transcriptomic profiling has led to innumerable advances in the biomedical space, but the characterization of RNA and protein expression is limited in its ability to inform on the functional characteristics of proteins. Given that transcript and protein expression... | Wikipedia - Chemoproteomics - Solution-based approaches | 151 | 906 | null |
Section: Solution-based approaches > Activity-based protein profiling. Activity-based protein profiling (ABPP, also activity-based proteomics) is a technique that was developed to monitor the availability of enzymatic active sites to their endogenous ligands. ABPP uses specially designed probes that enter and form a co... | Wikipedia - Chemoproteomics - Solution-based approaches > Activity-based protein profiling | 325 | 1,461 | null |
The most widely used reporters are fluorescent moieties that enable imaging and affinity tags, such as biotin, that allow for pull-down of labeled enzymes and analysis via mass spectrometry. There are drawbacks to each strategy, namely that fluorescent reporters do not allow for enrichment for proteomic analysis, while... | Wikipedia - Chemoproteomics - Solution-based approaches > Activity-based protein profiling | 347 | 1,691 | null |
Section: Solution-based approaches > Photoaffinity labeling. Unlike ABPP, which results in protein labeling upon probe binding, photoaffinity labeling probes require activation by photolysis before covalent bonding to a protein occurs. The presence of a photoreactive group makes this possible. These probes are composed... | Wikipedia - Chemoproteomics - Solution-based approaches > Photoaffinity labeling | 326 | 1,470 | null |
Section: Immobilization-based approaches > Microbead-based immobilization. Microbead-based immobilization is a modular technique in that it allows the investigator to decide whether they wish to fish for protein targets from the proteome or drug-like compounds from chemical libraries. The macroscopic properties of micr... | Wikipedia - Chemoproteomics - Immobilization-based approaches > Microbead-based immobilization | 312 | 1,455 | null |
Conversely, a ligand of interest can be immobilized and screened against proteome proteins by incubation with a lysate. Hybrid solution- and immobilization-based strategies have been applied, in which ligands functionalized with an enrichment tag, such as biotin, are allowed to float freely in solution and find their t... | Wikipedia - Chemoproteomics - Immobilization-based approaches > Microbead-based immobilization | 208 | 982 | null |
Section: Immobilization-based approaches > Affinity chromatography. Affinity chromatography emerged in the 1950s as a rarely used method used to purify enzymes; it has since seen mainstream use and is the oldest among chemoproteomic approaches. Affinity chromatography is performed following one of two basic formats: li... | Wikipedia - Chemoproteomics - Immobilization-based approaches > Affinity chromatography | 279 | 1,301 | null |
Section: Derivatization-free approaches. While the approaches above have shown success, they are inherently limited by their need for derivatization, which jeopardizes the affinity of the interaction that derivatized compounds are said to emulate and introduces steric hindrance. Immobilized ligands and targets are limi... | Wikipedia - Chemoproteomics - Derivatization-free approaches | 311 | 1,629 | null |
Section: Derivatization-free approaches > Thermal proteome profiling (TPP). Thermal proteome profiling (also, Cellular Thermal Shift Assay) is recently popularized strategy to infer ligand-protein interactions from shifts in protein thermal stability induced by ligand binding. In a typical assay setup, protein-containi... | Wikipedia - Chemoproteomics - Derivatization-free approaches > Thermal proteome profiling (TPP) | 298 | 1,444 | null |
Section: Derivatization-free approaches > Drug affinity responsive target stability (DARTS). The Drug Affinity Responsive Target Stability assay follows a similar basic assumption to TPP – that protein stability is increased by ligand binding. In DARTS, however, protein stability is assessed in response to digestion by... | Wikipedia - Chemoproteomics - Derivatization-free approaches > Drug affinity responsive target stability (DARTS) | 214 | 1,014 | null |
Section: Derivatization-free approaches > Stability of proteins from rates of oxidation (SPROX). Stability of Proteins from Rates of Oxidation also rests upon the assumption that ligand binding confers protection to proteins from manners of degradation, this time from oxidation of methionine residues. In SPROX, a lysat... | Wikipedia - Chemoproteomics - Derivatization-free approaches > Stability of proteins from rates of oxidation (SPROX) | 342 | 1,594 | null |
Section: Derivatization-free approaches > Affinity selection-mass spectrometry. While adoption of affinity selection-mass spectrometry (AS-MS) has led to an expansion of assay formats, the general technique follows a simple scheme. Protein targets are incubated with small molecules to allow for the formation of stable ... | Wikipedia - Chemoproteomics - Derivatization-free approaches > Affinity selection-mass spectrometry | 294 | 1,404 | null |
Section: Derivatization-free approaches > Affinity selection-mass spectrometry > Affinity selection. A generalized AS-MS workflow begins with the pre-incubation of purified protein solutions (i.e. target proteins) with chemical libraries in microplates. Assays can be designed to contain sufficiently high protein concen... | Wikipedia - Chemoproteomics - Derivatization-free approaches > Affinity selection-mass spectrometry > Affinity selection | 270 | 1,400 | null |
Section: Derivatization-free approaches > Affinity selection-mass spectrometry > Separation of unbound small molecules and ligand-protein complexes. Affinity selection is followed by the removal of unbound small molecules via ultrafiltration or size-exclusion chromatography, making only protein-bound ligands available ... | Wikipedia - Chemoproteomics - Derivatization-free approaches > Affinity selection-mass spectrometry > Separation of unbound small molecules and ligand-protein complexes | 339 | 1,696 | null |
In either case, a mixture of unbound ligands, proteins, ligand-protein complexes is passed through a column of porous beads. Ligand-protein complexes are excluded from entering the beads and exit the column quickly, while unbound ligands must travel through the beads and are retained by the column for a longer time. Li... | Wikipedia - Chemoproteomics - Derivatization-free approaches > Affinity selection-mass spectrometry > Separation of unbound small molecules and ligand-protein complexes | 269 | 1,219 | null |
Section: Derivatization-free approaches > Affinity selection-mass spectrometry > Analysis of bound ligands. The final step requires bioanalytical separation of bound ligands from their targets, and subsequent identification of ligands using liquid chromatography-mass spectrometry. AS-MS offers means for identifying sma... | Wikipedia - Chemoproteomics - Derivatization-free approaches > Affinity selection-mass spectrometry > Analysis of bound ligands | 264 | 1,324 | null |
Section: Derivatization-free approaches > Target identification by chromatographic co-elution (TICC). Target identification by chromatographic co-elution does not rely on differences in protein stability after drug treatment. Instead, it rests on the assumption that drugs form stable complexes with their target protein... | Wikipedia - Chemoproteomics - Derivatization-free approaches > Target identification by chromatographic co-elution (TICC) | 209 | 997 | null |
Section: Computational approaches > Molecular docking simulations > Ligand-based methods. When a bioactive ligand with a known structure is to be screened against a protein with limited structural information, modeling is done with regard to ligand structure. Pharmacophore modeling identifies key electronic and structu... | Wikipedia - Chemoproteomics - Computational approaches > Molecular docking simulations > Ligand-based methods | 305 | 1,723 | null |
Section: Computational approaches > Molecular docking simulations > Structure-based methods. Ideally, the structure of a drug target is known, which allows for structure-based pharmacophore modeling. A structure-based model integrates key structural properties of the protein's binding site, such as the spatial distribu... | Wikipedia - Chemoproteomics - Computational approaches > Molecular docking simulations > Structure-based methods | 259 | 1,319 | null |
Section: Applications > Druggability. Chemoproteomic strategies have been used to expand the scope of druggable targets. While historically successful drugs target well-defined binding pockets of druggable proteins, these define only about 15% of the annotated proteome. To continue growing our pharmacopoeia, bold appro... | Wikipedia - Chemoproteomics - Applications > Druggability | 310 | 1,448 | null |
Section: Applications > Drug repurposing. Chemoproteomics is at the forefront of drug repurposing. This is particularly relevant in the era of COVID-19, which saw a dire need to rapidly identify FDA approved drugs that have antiviral activity. In this context, a phenotypic screen is usually employed to identify drugs w... | Wikipedia - Chemoproteomics - Applications > Drug repurposing | 235 | 982 | null |
Section: Applications > High-throughput screening. Approved drugs are never identified as hits in high-throughput screens because the chemical libraries used in screening have not been optimized against any targets. However, methods like affinity chromatography and affinity selection-mass spectrometry are workhorses of... | Wikipedia - Chemoproteomics - Applications > High-throughput screening | 171 | 838 | null |
Section: Background. For a wave function Ψ = ∑ i C i Φ i {\displaystyle \Psi =\sum \limits _{i}C_{i}\Phi _{i}} where Φ 1 , Φ 2 , … , Φ n {\displaystyle \Phi _{1},\Phi _{2},\dots ,\Phi _{n}} are a linearly independent, orthogonal set of basis orbitals, the weight of a constituent orbital Ψ i {\displaystyle \Psi _{i}} wo... | Wikipedia - Chirgwin–Coulson weights - Background | 295 | 984 | null |
Section: Rigorous formulation > Determination of VB Structures > Rumer's method. A method of creating a linearly independent, complete set of valence bond structures for a molecule was proposed by Yuri Rumer. For a system with n electrons and n orbitals, Rumer's method involves arranging the orbitals in a circle and co... | Wikipedia - Chirgwin–Coulson weights - Rigorous formulation > Determination of VB Structures > Rumer's method | 276 | 1,161 | null |
The resulting VB structures can be represented by a linear combination of determinants | a b ¯ c d ¯ | {\displaystyle |a{\overline {b}}c{\overline {d}}|} , where a letter without an over-line indicates an electron with α {\displaystyle \alpha } spin, while a letter with over-line indicates an electron with β {\displays... | Wikipedia - Chirgwin–Coulson weights - Rigorous formulation > Determination of VB Structures > Rumer's method | 249 | 704 | null |
The VB structure for 1, for example would be a linear combination of the determinants | 1 2 ¯ 3 4 ¯ | {\displaystyle |1{\overline {2}}3{\overline {4}}|} , | 2 1 ¯ 3 4 ¯ | {\displaystyle |2{\overline {1}}3{\overline {4}}|} , | 1 2 ¯ 4 3 ¯ | {\displaystyle |1{\overline {2}}4{\overline {3}}|} , and | 2 1 ¯ 4 3 ¯ | {\displ... | Wikipedia - Chirgwin–Coulson weights - Rigorous formulation > Determination of VB Structures > Rumer's method | 340 | 767 | null |
Section: Rigorous formulation > Determination of VB Structures > Matrix representation of VB structures. An arbitrary VB structure | φ 1 φ 2 ¯ φ 3 φ 4 ¯ … | {\displaystyle |\varphi _{1}{\overline {\varphi _{2}}}\varphi _{3}{\overline {\varphi _{4}}}\dots |} containing n {\displaystyle n} electrons, represented by the e... | Wikipedia - Chirgwin–Coulson weights - Rigorous formulation > Determination of VB Structures > Matrix representation of VB structures | 206 | 603 | null |
An arbitrary VB structure | φ 1 φ 2 ¯ φ 3 φ 4 ¯ … | {\displaystyle |\varphi _{1}{\overline {\varphi _{2}}}\varphi _{3}{\overline {\varphi _{4}}}\dots |} containing n {\displaystyle n} electrons, represented by the electron indices 1 , 2 , … , n {\displaystyle 1,2,\dots ,n} , and n {\displaystyle n} orbitals, represente... | Wikipedia - Chirgwin–Coulson weights - Rigorous formulation > Determination of VB Structures > Matrix representation of VB structures | 529 | 1,194 | null |
An arbitrary VB structure | φ 1 φ 2 ¯ φ 3 φ 4 ¯ … | {\displaystyle |\varphi _{1}{\overline {\varphi _{2}}}\varphi _{3}{\overline {\varphi _{4}}}\dots |} containing n {\displaystyle n} electrons, represented by the electron indices 1 , 2 , … , n {\displaystyle 1,2,\dots ,n} , and n {\displaystyle n} orbitals, represente... | Wikipedia - Chirgwin–Coulson weights - Rigorous formulation > Determination of VB Structures > Matrix representation of VB structures | 848 | 1,855 | null |
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