text stringlengths 14 4.79k | source stringlengths 13 304 | tokens float64 75 1.06k ⌀ | char_length float64 106 4.79k ⌀ | article_title stringlengths 16 300 ⌀ |
|---|---|---|---|---|
Section: Markets > Target markets > Other specialty chemical industries. Apart from life sciences, specialty chemicals -and therefore also their active ingredients, commodities or fine chemicals, as the case may be- are used ubiquitously, in both industrial applications, such as biocides and corrosion inhibitors in coo... | Wikipedia - Fine chemical - Markets > Target markets > Other specialty chemical industries | 335 | 1,618 | null |
Section: Markets > Target products and services > Custom manufacturing. The products and services offered by the fine chemical industry fall into two broad categories: (1) "Exclusives", a.k.a. custom manufacturing (CM) and (2) "standard" or "catalogue" products. "Exclusives", provided mostly under contract research or ... | Wikipedia - Fine chemical - Markets > Target products and services > Custom manufacturing | 269 | 1,350 | null |
Section: Markets > Target products and services > Standard products. Non-exclusives, "standard" or "catalogue products" constitute the second most important outlet for fine chemicals after custom manufacturing. API-for-Generics are the most important sub-category. Because of patent expiries, over 60 of the top 200 drug... | Wikipedia - Fine chemical - Markets > Target products and services > Standard products | 158 | 840 | null |
Section: Financials > Investment costs. Investment costs for multipurpose plants are high in comparison with product output. However, they vary considerably, depending on the location, size of equipment and degree of sophistication (e.g., automation, containment, quality of equipment, complexity of infrastructure). An ... | Wikipedia - Fine chemical - Financials > Investment costs | 280 | 1,385 | null |
Section: Financials > Manufacturing costs. The raw material consumption and the conversion cost are the two elements that establish the manufacturing cost for a particular fine chemical. The former is determined primarily by the unit consumption and the purchasing cost of the materials used; the latter, by the throughp... | Wikipedia - Fine chemical - Financials > Manufacturing costs | 340 | 1,749 | null |
Section: Financials > Profitability. The fine chemical industry has undergone several boom and bust phases during its almost 30 years of existence. The biggest boom took place in the late 1990s, when high-dosage, high volume anti-AIDS drugs and COX-2 inhibitors gave a big boost to custom manufacturing. After the end of... | Wikipedia - Fine chemical - Financials > Profitability | 347 | 1,588 | null |
At the end of the "irrational exuberance" at the turn of the millennium and again in 2009 almost half of the industry achieved a return on sales (ROS) of more than 10%, and less than 10% an ROS below 5%. In the worst years, 2003 and 2009, almost half of the companies suffered from an ROS of less than 5%. Whereas during... | Wikipedia - Fine chemical - Financials > Profitability | 209 | 837 | null |
Section: Outlook. Two main trends impinge on the industry. On the supply side, biotechnology is rapidly gaining importance. In the synthesis of small molecule fine chemicals, the use of biocatalysts and microbial fermentation enable both a more sustainable and economic production than conventional organic chemistry. In... | Wikipedia - Fine chemical - Outlook | 333 | 1,621 | null |
In agro fine chemicals, the active ingredients become more sophisticated and performing. Therefore, they require multipurpose instead of dedicated plants prevailing in the industry so far. At the same token, outsourcing is gaining ground. Globalization results in a shift of fine chemical production from the industriali... | Wikipedia - Fine chemical - Outlook | 343 | 1,891 | null |
Article: Flippin–Lodge angle. The Flippin–Lodge angle is one of two angles used by organic and biological chemists studying the relationship between a molecule's chemical structure and ways that it reacts, for reactions involving "attack" of an electron-rich reacting species, the nucleophile, on an electron-poor reacti... | Wikipedia - Flippin–Lodge angle - Summary | 282 | 1,260 | null |
Because chemical reactions take place in three dimensions, their quantitative description is, in part, a geometry problem. Two angles, first the Bürgi–Dunitz angle, α B D {\displaystyle \alpha _{BD}} , and later the Flippin–Lodge angle, α F L {\displaystyle \alpha _{FL}} , were developed to describe the approach of the... | Wikipedia - Flippin–Lodge angle - Summary | 331 | 1,271 | null |
These nucleophiles can be paired with an array of planar electrophiles: aldehydes and ketones, carboxylic acid-derivatives, and the carbon-carbon double bonds of alkenes. Studies of α B D {\displaystyle \alpha _{BD}} and α F L {\displaystyle \alpha _{FL}} can be theoretical, based on calculations, or experimental (eith... | Wikipedia - Flippin–Lodge angle - Summary | 342 | 1,489 | null |
Section: Technical introduction. The Flippin–Lodge (FL) angle, α F L {\displaystyle \alpha _{FL}} is the latter-derived of two angles that fully define the geometry of "attack" (approach via collision) of a nucleophile on a trigonal unsaturated center of an electrophilic molecule (the second being the Bürgi–Dunitz angl... | Wikipedia - Flippin–Lodge angle - Technical introduction | 344 | 1,376 | null |
Planar electrophiles include aldehydes and ketones, carboxylic acid-derivatives such as esters, and amides, and the carbon-carbon double bonds of particular alkenes (olefins). In the example of nucleophilic attack at a carbonyl, α F L {\displaystyle \alpha _{FL}} is a measure of the "offset" of the nucleophile's approa... | Wikipedia - Flippin–Lodge angle - Technical introduction | 346 | 1,366 | null |
Dunitz, its first senior investigators (see that related article). The Flippin–Lodge angle has been abbreviated variously by the symbols φ, ψ, θx, and α {\displaystyle \alpha } or α F L {\displaystyle \alpha _{FL}} ; the latter pair to closely associate the Flippin–Lodge angle with its sister angle, the Bürgi–Dunitz, w... | Wikipedia - Flippin–Lodge angle - Technical introduction | 180 | 636 | null |
Section: As an experimental observable. These angles are best construed to mean the angles observed (measured) for a given system, and not an historically observed range in values (e.g., as in the α B D {\displaystyle \alpha _{BD}} range of the original Bürgi–Dunitz aminoketones), or an idealized value computed for a p... | Wikipedia - Flippin–Lodge angle - As an experimental observable | 243 | 943 | null |
That is, the α B D {\displaystyle \alpha _{BD}} and α F L {\displaystyle \alpha _{FL}} angles of the hydride-formadehyde system have one pair of values, while the angles observed for other systems—combinations of nucelophile and electrophile, in combination with catalyst and other variables that define the experimental... | Wikipedia - Flippin–Lodge angle - As an experimental observable | 307 | 1,161 | null |
In contrast to the Bürgi–Dunitz angle, α B D {\displaystyle \alpha _{BD}} , and using the case of carbonyl additions as example: the α F L {\displaystyle \alpha _{FL}} angle adopted during an approach by the nucleophile to a trigonal electrophile depends in complex fashion on: the relative steric size of the two substi... | Wikipedia - Flippin–Lodge angle - Steric and orbital contributions to its value | 350 | 1,257 | null |
nucleophile. Hence, the α B D {\displaystyle \alpha _{BD}} observed for nucleophilic attack appears to be influenced primarily by the energetics of the HOMO-LUMO overlap of the nucleophile-electrophile pair in the systems studied—see the Bürgi–Dunitz article, and the related inorganic chemistry concept of the angular o... | Wikipedia - Flippin–Lodge angle - Steric and orbital contributions to its value | 164 | 646 | null |
Section: Origin and current scope of concept. Bürgi–Dunitz angle theory was initially developed based on "frozen" interactions in crystals,: 124ff while most chemistry takes place via collisions of molecules tumbling in solution; remarkably, the theories of the α F L {\displaystyle \alpha _{FL}} , with the complexity t... | Wikipedia - Flippin–Lodge angle - Origin and current scope of concept | 315 | 1,305 | null |
As well, dynamics are at play in each system (e.g., changing torsional angles) and are implicitly included in studies of reaction outcomes in solution, as in the early studies of α F L {\displaystyle \alpha _{FL}} ,—though not in crystallographic structure correlation approaches as gave birth to the BD concept. Finally... | Wikipedia - Flippin–Lodge angle - Origin and current scope of concept | 293 | 1,235 | null |
For instance, while a simple amide addition study with relatively small substituents gave an α F L {\displaystyle \alpha _{FL}} of ≈50° in solution, the crystallographic value determined for an enzymatic cleavage of an amide by the serine protease subtilisin gave an α F L {\displaystyle \alpha _{FL}} of 8°, and a compi... | Wikipedia - Flippin–Lodge angle - Origin and current scope of concept | 274 | 987 | null |
Section: Applications. The Flippin-Lodge and Bürgi-Dunitz angles were central, practically, to the development of a clearer understanding of asymmetric induction during nucleophilic attack at hindered carbonyl centers in synthetic organic chemistry. It was in this area that α F L {\displaystyle \alpha _{FL}} was first ... | Wikipedia - Flippin–Lodge angle - Applications | 258 | 1,012 | null |
Likewise, if bulky a nucleophile, such as a t-butylmethylsilyl enolate, is used, the selectivity is higher than for a small nucleophile like a lithium enolate. Given a reaction system of a given nucleophile with a carbonyl having the two substituents R and R', where substituent R' is sterically small relative to substi... | Wikipedia - Flippin–Lodge angle - Applications | 344 | 1,325 | null |
Thus, from the perspective of simpler electrophile systems where only steric bulk come into play, the attack trajectories of the classes of nucleophiles studied makes clear that as the disparity in size between the substituent increase, there is a perturbation in the FL angle that can be used to provide higher stereose... | Wikipedia - Flippin–Lodge angle - Applications | 299 | 1,401 | null |
Article: Functional group. In organic chemistry, a functional group is any substituent or moiety in a molecule that causes the molecule's characteristic chemical reactions. The same functional group will undergo the same or similar chemical reactions regardless of the rest of the molecule's composition. This enables sy... | Wikipedia - Functional group - Summary | 319 | 1,621 | null |
For example, sugar dissolves in water because both share the hydroxyl functional group (−OH) and hydroxyls interact strongly with each other. Plus, when functional groups are more electronegative than atoms they attach to, the functional groups will become polar, and the otherwise nonpolar molecules containing these fu... | Wikipedia - Functional group - Summary | 326 | 1,449 | null |
Section: Table of common functional groups > Hydrocarbons. Hydrocarbons are a class of molecule that is defined by functional groups called hydrocarbyls that contain only carbon and hydrogen, but vary in the number and order of double bonds. Each one differs in type (and scope) of reactivity. There are also a large num... | Wikipedia - Functional group - Table of common functional groups > Hydrocarbons | 183 | 746 | null |
Section: Table of common functional groups > Names of radicals or moieties. These names are used to refer to the moieties themselves or to radical species, and also to form the names of halides and substituents in larger molecules. When the parent hydrocarbon is unsaturated, the suffix ("-yl", "-ylidene", or "-ylidyne"... | Wikipedia - Functional group - Table of common functional groups > Names of radicals or moieties | 295 | 1,004 | null |
Article: Gelation. In polymer chemistry, gelation (gel transition) is the formation of a gel from a system with polymers. Branched polymers can form links between the chains, which lead to progressively larger polymers. As the linking continues, larger branched polymers are obtained and at a certain extent of the react... | Wikipedia - Gelation - Summary | 152 | 738 | null |
Section: Quantitative approaches to determine gelation > Average functionality approach. According to the Carothers equation number-average degree of polymerization D P n {\displaystyle DP_{n}} is given by D P n = 2 2 − p . f a v {\displaystyle DP_{n}={\frac {2}{2-p.f_{av}}}} where p {\displaystyle p} is the extent of ... | Wikipedia - Gelation - Quantitative approaches to determine gelation > Average functionality approach | 224 | 707 | null |
Section: Quantitative approaches to determine gelation > Flory Stockmayer approach. Flory and Stockmayer used a statistical approach to derive an expression to predict the gel point by calculating when D P n {\displaystyle DP_{n}} approaches infinite size. The statistical approach assumes that (1) the reactivity of the... | Wikipedia - Gelation - Quantitative approaches to determine gelation > Flory Stockmayer approach | 247 | 995 | null |
The ratio of all A groups, both reacted and unreacted, that are part of branched units, to the total number of A groups in the mixture is defined as ρ {\displaystyle \rho } . This will lead to the following reaction A − A + B − B + A f → A f − 1 − ( B − B A − A ) n B − B A − A f − 1 {\displaystyle A-A+B-B+A_{f}\rightar... | Wikipedia - Gelation - Quantitative approaches to determine gelation > Flory Stockmayer approach | 277 | 736 | null |
This will lead to the following reaction A − A + B − B + A f → A f − 1 − ( B − B A − A ) n B − B A − A f − 1 {\displaystyle A-A+B-B+A_{f}\rightarrow A_{f-1}-(B-BA-A)_{n}B-BA-A_{f-1}} The probability of obtaining the product of the reaction above is given by p A [ p B ( 1 − ρ ) p A ] n p B ρ {\displaystyle p_{A}[p_{B}(1... | Wikipedia - Gelation - Quantitative approaches to determine gelation > Flory Stockmayer approach | 330 | 821 | null |
This relation yields to an expression for the extent of reaction of A functional groups at the gel point p c = 1 { r [ 1 + ρ ( f − 2 ) ] } 1 / 2 {\displaystyle p_{c}={\frac {1}{\{r[1+\rho (f-2)]\}^{1/2}}}} where r is the ratio of all A groups to all B groups. If more than one type of multifunctional branch unit is pres... | Wikipedia - Gelation - Quantitative approaches to determine gelation > Flory Stockmayer approach | 163 | 567 | null |
Article: Glycorandomization. Glycorandomization, is a drug discovery and drug development technology platform to enable the rapid diversification of bioactive small molecules, drug leads and/or approved drugs through the attachment of sugars. Initially developed as a facile method to manipulate carbohydrate substitutio... | Wikipedia - Glycorandomization - Summary | 175 | 798 | null |
Section: Classification. The traditional method for attaching sugars to natural products, drugs or drug leads is by chemical glycosylation. This classical approach typically requires multiple protection/deprotection steps in addition to the key anomeric activation/coupling reaction which, depending upon the glycosyl do... | Wikipedia - Glycorandomization - Classification | 237 | 1,048 | null |
Section: Classification > Chemoenzymatic glycorandomization. Chemoenzymatic glycorandomization was inspired by the early pathway engineering work of Hutchinson and coworkers that suggested natural product glycosyltransferases were capable of utilizing non-native sugar nucleotide donors. The initial platform for chemoen... | Wikipedia - Glycorandomization - Classification > Chemoenzymatic glycorandomization | 308 | 1,294 | null |
Section: Classification > Neoglycorandomization. Neoglycorandomization is a chemoselective glycodiversification method inspired by the alkoxyamine-based ‘neoglycosylation’ reaction first described Peri and Dumy. This reaction proceeds via an oxy-iminium intermediate to ultimately provide the more thermodynamically-favo... | Wikipedia - Glycorandomization - Classification > Neoglycorandomization | 251 | 1,105 | null |
Section: Classification > Comparison. Both chemoenzymatic glycorandomization and neoglycorandomization use free reducing sugars and unprotected aglycons and are thereby a notable advance over classical glycosylation methods. A notable advantage of the enzymatic approach is the use of the corresponding genes encoding fo... | Wikipedia - Glycorandomization - Classification > Comparison | 211 | 886 | null |
Article: Homoenolates. Homoenolates are a type of functional group that have been used in synthetic organic chemistry since the 1980s. They are related to enolates, but represent an umpolung of their reactivity. Homoenolates can be formed with a variety of different metal counterions, including lithium, iron, silver, l... | Wikipedia - Homoenolates - Summary | 160 | 714 | null |
Article: Homologous series. In organic chemistry, a homologous series is a sequence of compounds with the same functional group and similar chemical properties in which the members of the series differ by the number of repeating units they contain. This can be the length of a carbon chain, for example in the straight-c... | Wikipedia - Homologous series - Summary | 337 | 1,554 | null |
Section: Examples. The homologous series of straight-chained alkanes begins methane (CH4), ethane (C2H6), propane (C3H8), butane (C4H10), and pentane (C5H12). In that series, successive members differ in mass by an extra methylene bridge (-CH2- unit) inserted in the chain. Thus the molecular mass of each member differs... | Wikipedia - Homologous series - Examples | 321 | 1,249 | null |
Article: Hydrogen-bond catalysis. Hydrogen-bond catalysis is a type of organocatalysis that relies on use of hydrogen bonding interactions to accelerate and control organic reactions. In biological systems, hydrogen bonding plays a key role in many enzymatic reactions, both in orienting the substrate molecules and lowe... | Wikipedia - Hydrogen-bond catalysis - Summary | 293 | 1,402 | null |
Section: Catalytic strategies > Stabilization of tetrahedral intermediates. Many organic reactions involve the formation of tetrahedral intermediates through nucleophilic attack of functional groups such as aldehydes, amides or imines. In these cases, catalysis with hydrogen-bond donors is an attractive strategy since ... | Wikipedia - Hydrogen-bond catalysis - Catalytic strategies > Stabilization of tetrahedral intermediates | 326 | 1,633 | null |
Many synthetic catalysts employ this strategy to activate a variety of electrophiles. Using a chiral BINOL catalyst, for instance, the Morita-Baylis-Hillman reaction involving the addition of enones to aldehydes can be effected with high enantioselectivity. The nucleophile is an enolate-type species generated from the ... | Wikipedia - Hydrogen-bond catalysis - Catalytic strategies > Stabilization of tetrahedral intermediates | 259 | 1,140 | null |
Section: Catalytic strategies > Stabilization of anionic fragments. Another strategy that has been explored is the stabilization of reactions that develop partial negative charges in the transition state. Examples of applications are most commonly reactions that are approximated concerted and pericyclic in nature. Duri... | Wikipedia - Hydrogen-bond catalysis - Catalytic strategies > Stabilization of anionic fragments | 306 | 1,411 | null |
Section: Catalytic strategies > Anion binding. Hydrogen-bond catalysts can also accelerate reactions by assisting in the formation of electrophilic species through abstracting and coordinating an anion such as a halide. Urea and thiourea catalysts are the most common donors in anion-binding catalysis, and their ability... | Wikipedia - Hydrogen-bond catalysis - Catalytic strategies > Anion binding | 335 | 1,436 | null |
The mechanism of formation of the oxocarbenium-thiourea-chloride complex is not fully resolved. It is thought that under the reaction conditions, the chloro ether can epimerize and thiourea can stereoselectively bind chloride to form a closely associated ion pair. This asymmetric ion pair is then attacked by the silane... | Wikipedia - Hydrogen-bond catalysis - Catalytic strategies > Anion binding | 304 | 1,339 | null |
Section: Catalytic strategies > Protonation. It is often difficult to distinguish between hydrogen-bond catalysis and general acid catalysis. Hydrogen-bond donors can have varying acidity, from mild to essentially strong Brønsted acids like phosphoric acids. Looking at the extent of proton transfer over the course of t... | Wikipedia - Hydrogen-bond catalysis - Catalytic strategies > Protonation | 279 | 1,410 | null |
Section: Catalytic strategies > Multifunctional strategies. One of the main advantages of hydrogen-bond catalysis is the ability to construct catalysts that engage in multiple non-covalent interactions to promote the reaction. In addition to using hydrogen-bond donors to activate or stabilize a reactive center during t... | Wikipedia - Hydrogen-bond catalysis - Catalytic strategies > Multifunctional strategies | 322 | 1,615 | null |
A combination of anion-binding and cation-pi strategies can be used to effect enantioselective cationic polycyclizations. In the transition state, it is proposed that the thiourea group binds chloride, while the aromatic system stabilizes the associated polyene cation. In support of this, increasing the size of the aro... | Wikipedia - Hydrogen-bond catalysis - Catalytic strategies > Multifunctional strategies | 350 | 1,575 | null |
A relatively new strategy of using synthetic oligopeptides to perform catalysis has yielded many examples of catalytic methods. Peptides feature multiple potential sites for hydrogen bonding and it is generally not understood how these engage substrate or how they promote reaction. Peptides have the advantage of being ... | Wikipedia - Hydrogen-bond catalysis - Catalytic strategies > Multifunctional strategies | 218 | 1,146 | null |
Section: Catalyst design > Privileged structures. The types of hydrogen-bond donors used in catalysis vary widely from reaction to reaction, even among similar catalytic strategies. While specific systems are often studied and optimized extensively, a general understanding of the optimal donor for a reaction or the rel... | Wikipedia - Hydrogen-bond catalysis - Catalyst design > Privileged structures | 341 | 1,663 | null |
Guanidinium and amidinium ions are structural relatives of ureas and thioureas and can catalyze similar reactions but, by virtue of their positive charge, are stronger donors and much more acidic. The mechanism of guanidinium and amidinium catalysis is thought to often involve partial protonation of substrate. Diol cat... | Wikipedia - Hydrogen-bond catalysis - Catalyst design > Privileged structures | 249 | 1,136 | null |
Section: Catalyst design > Catalyst tuning. In general, acidity of donor sites correlates well with the strength of the donor. For example, it is a common strategy to add electron-withdrawing aryl substituents on a thiourea catalyst, which can increase its acidity and thus the strength of its hydrogen bonding. However,... | Wikipedia - Hydrogen-bond catalysis - Catalyst design > Catalyst tuning | 309 | 1,409 | null |
Section: Synthetic applications > Natural product synthesis. To date, there have been few examples of hydrogen-bond catalysis in the synthesis of natural products despite the large number of reactions being discovered. Generally, with high required catalyst loading and often extreme substrate specificity, hydrogen-bond... | Wikipedia - Hydrogen-bond catalysis - Synthetic applications > Natural product synthesis | 249 | 1,079 | null |
Section: Synthetic applications > Scalable synthesis of building blocks. Aside from total synthesis, hydrogen-bond catalysis has been applied to the bulk synthesis of difficult-to-access chiral small molecules. An example is the gram-scale Strecker synthesis of unnatural amino acids using thiourea catalysis, reported i... | Wikipedia - Hydrogen-bond catalysis - Synthetic applications > Scalable synthesis of building blocks | 159 | 673 | null |
Article: Immobilized enzyme. An immobilized enzyme is an enzyme, with restricted mobility, attached to an inert, insoluble material—such as calcium alginate (produced by reacting a mixture of sodium alginate solution and enzyme solution with calcium chloride). This can provide increased resistance to changes in conditi... | Wikipedia - Immobilized enzyme - Summary | 232 | 1,155 | null |
Section: Considerations. Before performing any kind of immobilization techniques, some factors should be in mind. It is necessary to understand the chemical and physical effects on an enzyme following immobilization. Enzyme stability and kinetic characteristics can be altered due to changes in the microenvironment cond... | Wikipedia - Immobilized enzyme - Considerations | 215 | 1,097 | null |
Section: Considerations > Support selection. For a support material to be ideal, it must be hydrophilic, inert towards enzymes, biocompatible, microbial attack and compression resistant, and must be affordable. Support materials can be organic or inorganic, synthetic or natural (depending on the composition), since the... | Wikipedia - Immobilized enzyme - Considerations > Support selection | 210 | 1,033 | null |
Section: Methods > Physical > Adsorption. A straightforward method for reversible immobilization, involving the enzymes being adsorbed or attached physically onto a support substance. Adsorption can take place through weak non-specific forces, such as van der waals, hydrogen bonds, and hydrophobic interactions, whereas... | Wikipedia - Immobilized enzyme - Methods > Physical > Adsorption | 155 | 716 | null |
Section: Methods > Chemical > Cross-linking. Cross-linkage: another irreversible method that does not require a support material for the attachment of enzyme molecules. In this technique, the molecules of enzymes are covalently bonded to each other to create a matrix consisting of almost only enzyme. The reaction ensur... | Wikipedia - Immobilized enzyme - Methods > Chemical > Cross-linking | 158 | 712 | null |
Section: Methods > Chemical > Covalent bonding. The enzyme is bound covalently to an insoluble support (such as silica gel or macroporous polymer beads with epoxide groups). This approach provides the strongest enzyme/support interaction, and so the lowest protein leakage during catalysis. The activity of the enzyme be... | Wikipedia - Immobilized enzyme - Methods > Chemical > Covalent bonding | 217 | 1,077 | null |
Section: Random versus site-directed. Numerous enzymes of biotechnological importance have been immobilized on various supports (inorganic, organic, composite and nanomaterials) via random multipoint attachment. However, immobilization via random chemical modification results in a heterogeneous protein population where... | Wikipedia - Immobilized enzyme - Random versus site-directed | 337 | 1,601 | null |
Section: Commercial use. Immobilized enzymes have important application uses as they reduce costs and improve the outcome of the reaction they catalyze. Advantages include: Convenience Minuscule amounts of protein dissolve in the reaction, so workup can be much easier. Upon completion, reaction mixtures typically conta... | Wikipedia - Immobilized enzyme - Commercial use | 327 | 1,569 | null |
Article: Inherent chirality. In chemistry, inherent chirality is a property of asymmetry in molecules arising, not from a stereogenic or chiral center, but from a twisting of the molecule in 3-D space. The term was first coined by Volker Boehmer in a 1994 review, to describe the chirality of calixarenes arising from th... | Wikipedia - Inherent chirality - Summary | 283 | 1,227 | null |
Section: History > Calixarenes. After creating a series of traditionally chiral calixarenes (through the addition of a chiral substituent group on the top or bottom rim of the macrocycle,) the first inherently chiral calixarenes were synthesized in 1982, though the molecules were not yet described as such. The inherent... | Wikipedia - Inherent chirality - History > Calixarenes | 150 | 661 | null |
Section: History > Definition. Due to the initial lack of a formal definition after the initial conception, the term inherent chirality was utilized to describe a variety of chiral molecules that don't fall into other defined chirality types. The first fully formulated definition of inherent chirality was published in ... | Wikipedia - Inherent chirality - History > Definition | 329 | 1,538 | null |
Section: Other examples. Spiro compounds (compounds with a twisted structure of two or more rings) can have inherent chirality at the spiroatom, due to the twisting of the achiral ring system. Inherently chiral alkenes have been synthesized through the use of a "buckle" where in an achiral, linear alkene is forced into... | Wikipedia - Inherent chirality - Other examples | 175 | 751 | null |
Section: Relative rates. In intramolecular organic reactions, two reaction sites are contained within a single molecule. This configuration elevates the effective concentration of the reacting partners resulting in high reaction rates. Many intramolecular reactions are observed where the intermolecular version does not... | Wikipedia - Intramolecular reaction - Relative rates | 332 | 1,526 | null |
The same reasoning holds for the 'unstrained rings' (5-, 6-, and 7-membered). The formation of 'medium-sized rings' (8- to 13-membered) is particularly disfavorable due to a combination of an increasingly unfavorable entropic cost and the additional presence of transannular strain arising from steric interactions acros... | Wikipedia - Intramolecular reaction - Relative rates | 173 | 729 | null |
Section: Examples. Many reactions in organic chemistry can occur in either an intramolecular or intermolecular senses. Some reactions are by definition intramolecular or are only practiced intramolecularly, e.g., Dieckmann condensation of diesters is the intramolecular version of aldol condensation. Madelung synthesis ... | Wikipedia - Intramolecular reaction - Examples | 247 | 1,017 | null |
Section: Tools and concepts > Tethered intramolecular [2+2] reactions. Tethered intramolecular [2+2] reactions entail the formation of cyclobutane and cyclobutanone via intramolecular 2+2 photocycloadditions. Tethering ensures formation of a multi-cyclic system. The length of the tether affects the stereochemical outco... | Wikipedia - Intramolecular reaction - Tools and concepts > Tethered intramolecular [2+2] reactions | 239 | 909 | null |
Section: Tools and concepts > Molecular tethers. Otherwise-intermolecular reactions can be made temporarily intramolecular by linking both reactants by a tether with all the advantages associated to it. Popular choices of tether contain a carbonate ester, boronic ester, silyl ether, or a silyl acetal link (silicon teth... | Wikipedia - Intramolecular reaction - Tools and concepts > Molecular tethers | 293 | 1,249 | null |
Article: IUPAC nomenclature of organic chemistry. In chemical nomenclature, the IUPAC nomenclature of organic chemistry is a method of naming organic chemical compounds as recommended by the International Union of Pure and Applied Chemistry (IUPAC). It is published in the Nomenclature of Organic Chemistry (informally c... | Wikipedia - IUPAC nomenclature of organic chemistry - Summary | 236 | 1,227 | null |
Section: Basic principles. In chemistry, a number of prefixes, suffixes and infixes are used to describe the type and position of the functional groups in the compound. The steps for naming an organic compound are: Identification of the most senior group. If more than one functional group, if any, is present, the one w... | Wikipedia - IUPAC nomenclature of organic chemistry - Basic principles | 341 | 1,483 | null |
For cyclic systems and chains after previous rules: It should have the maximum number of multiple, then double bonds. It should have the maximum number of substituents of the suffix functional group. By suffix, it is meant that the parent functional group should have a suffix, unlike halogen substituents. If more than ... | Wikipedia - IUPAC nomenclature of organic chemistry - Basic principles | 338 | 1,487 | null |
This is done by first numbering the chain in both directions (left to right and right to left), and then choosing the numbering which follows these rules, in order of precedence. Not every rule will apply to every compound, rules can be skipped if they do not apply. Has the lowest-numbered locant (or locants) for heter... | Wikipedia - IUPAC nomenclature of organic chemistry - Basic principles | 301 | 1,252 | null |
Numbering of the various substituents and bonds with their locants. If there is more than one of the same type of substituent/double bond, a prefix is added showing how many there are (di – 2, tri – 3, tetra – 4, then as for the number of carbons below with 'a' added at the end) The numbers for that type of side chain ... | Wikipedia - IUPAC nomenclature of organic chemistry - Basic principles | 291 | 1,177 | null |
Arrangement in this form: Group of side chains and secondary functional groups with numbers made in step 6 + prefix of parent hydrocarbon chain (eth, meth) + double/triple bonds with numbers (or "ane") + primary functional group suffix with numbers.Wherever it says "with numbers", it is understood that between the word... | Wikipedia - IUPAC nomenclature of organic chemistry - Basic principles | 348 | 1,284 | null |
Section: Basic principles > Example. Here is a sample molecule with the parent carbons numbered: For simplicity, here is an image of the same molecule, where the hydrogens in the parent chain are removed and the carbons are shown by their numbers: Now, following the above steps: The parent hydrocarbon chain has 23 carb... | Wikipedia - IUPAC nomenclature of organic chemistry - Basic principles > Example | 291 | 1,174 | null |
The side chains are grouped like this: 12-butyl-4,8-diethyl. (But this is not necessarily the final grouping, as functional groups may be added in between to ensure all groups are listed alphabetically.) The secondary functional groups are: a hydroxy- at carbon 5, a chloro- at carbon 11, a methoxy- at carbon 15, and a ... | Wikipedia - IUPAC nomenclature of organic chemistry - Basic principles > Example | 295 | 968 | null |
The arrangement (with punctuation) is: 18-bromo-12-butyl-11-chloro-4,8-diethyl-5-hydroxy-15-methoxytricosa-6,13-dien-19-yne-3,9-dione Finally, due to cis-trans isomerism, we have to specify the relative orientation of functional groups around each double bond. For this example, both double bonds are trans isomers, so w... | Wikipedia - IUPAC nomenclature of organic chemistry - Basic principles > Example | 179 | 458 | null |
Section: Hydrocarbons > Alkanes. Straight-chain alkanes take the suffix "-ane" and are prefixed depending on the number of carbon atoms in the chain, following standard rules. The first few are: For example, the simplest alkane is CH4 methane, and the nine-carbon alkane CH3(CH2)7CH3 is named nonane. The names of the fi... | Wikipedia - IUPAC nomenclature of organic chemistry - Hydrocarbons > Alkanes | 308 | 1,135 | null |
For example, (CH3)2CHCH3, commonly known as isobutane, is treated as a propane chain with a methyl group bonded to the middle (2) carbon, and given the systematic name 2-methylpropane. However, although the name 2-methylpropane could be used, it is easier and more logical to call it simply methylpropane – the methyl gr... | Wikipedia - IUPAC nomenclature of organic chemistry - Hydrocarbons > Alkanes | 347 | 1,307 | null |
Section: Hydrocarbons > Alkenes. Alkenes are named for their parent alkane chain with the suffix "-ene" and a numerical root indicating the position of the carbon with the lower number for each double bond in the chain: CH2=CHCH2CH3 is but-1-ene. Multiple double bonds take the form -diene, -triene, etc., with the size ... | Wikipedia - IUPAC nomenclature of organic chemistry - Hydrocarbons > Alkenes | 219 | 731 | null |
Section: Functional groups > Haloalkanes and haloarenes. In haloalkanes and haloarenes (R−X), Halogen functional groups are prefixed with the bonding position and take the form of fluoro-, chloro-, bromo-, iodo-, etc., depending on the halogen. Multiple groups are dichloro-, trichloro-, etc., and dissimilar groups are ... | Wikipedia - IUPAC nomenclature of organic chemistry - Functional groups > Haloalkanes and haloarenes | 162 | 486 | null |
Section: Functional groups > Ethers. Ethers (R−O−R) consist of an oxygen atom between the two attached carbon chains. The shorter of the two chains becomes the first part of the name with the -ane suffix changed to -oxy, and the longer alkane chain becomes the suffix of the name of the ether. Thus, CH3OCH3 is methoxyme... | Wikipedia - IUPAC nomenclature of organic chemistry - Functional groups > Ethers | 257 | 958 | null |
Section: Functional groups > Aldehydes. Aldehydes (R−CH=O) take the suffix "-al". If other functional groups are present, the chain is numbered such that the aldehyde carbon is in the "1" position, unless functional groups of higher precedence are present. If a prefix form is required, "oxo-" is used (as for ketones), ... | Wikipedia - IUPAC nomenclature of organic chemistry - Functional groups > Aldehydes | 202 | 739 | null |
Section: Functional groups > Carboxylic acids. In general, carboxylic acids (R−C(=O)OH) are named with the suffix -oic acid (etymologically a back-formation from benzoic acid). As with aldehydes, the carboxyl functional group must take the "1" position on the main chain and so the locant need not be stated. For example... | Wikipedia - IUPAC nomenclature of organic chemistry - Functional groups > Carboxylic acids | 336 | 1,257 | null |
Section: Functional groups > Carboxylates. Salts of carboxylic acids are named following the usual cation-then-anion conventions used for ionic compounds in both IUPAC and common nomenclature systems. The name of the carboxylate anion (R−C(=O)O−) is derived from that of the parent acid by replacing the "–oic acid" endi... | Wikipedia - IUPAC nomenclature of organic chemistry - Functional groups > Carboxylates | 211 | 747 | null |
Section: Functional groups > Esters. Esters (R−C(=O)O−R') are named as alkyl derivatives of carboxylic acids. The alkyl (R') group is named first. The R−C(=O)O part is then named as a separate word based on the carboxylic acid name, with the ending changed from "-oic acid" to "-oate" or "-carboxylate" For example, CH3C... | Wikipedia - IUPAC nomenclature of organic chemistry - Functional groups > Esters | 332 | 990 | null |
Section: Functional groups > Acid anhydrides. Acid anhydrides (R−C(=O)−O−C(=O)−R) have two acyl groups linked by an oxygen atom. If both acyl groups are the same, then the name of the carboxylic acid with the word acid is replaced with the word anhydride and the IUPAC name consists of two words. If the acyl groups are ... | Wikipedia - IUPAC nomenclature of organic chemistry - Functional groups > Acid anhydrides | 171 | 576 | null |
Section: Functional groups > Amines. Amines (R−NH2) are named for the attached alkane chain with the suffix "-amine" (e.g., CH3NH2 methanamine). If necessary, the bonding position is suffixed: CH3CH2CH2NH2 propan-1-amine, CH3CHNH2CH3 propan-2-amine. The prefix form is "amino-". For secondary amines (of the form R−NH−R)... | Wikipedia - IUPAC nomenclature of organic chemistry - Functional groups > Amines | 223 | 699 | null |
Section: Functional groups > Amides. Amides (R−C(=O)NH2) take the suffix "-amide", or "-carboxamide" if the carbon in the amide group cannot be included in the main chain. The prefix form is "carbamoyl-". e.g., HCONH2 methanamide, CH3CONH2 ethanamide. Amides that have additional substituents on the nitrogen are treated... | Wikipedia - IUPAC nomenclature of organic chemistry - Functional groups > Amides | 159 | 492 | null |
Section: Functional groups > Cyclic compounds. Cycloalkanes and aromatic compounds can be treated as the main parent chain of the compound, in which case the positions of substituents are numbered around the ring structure. For example, the three isomers of xylene CH3C6H4CH3, commonly the ortho-, meta-, and para- forms... | Wikipedia - IUPAC nomenclature of organic chemistry - Functional groups > Cyclic compounds | 214 | 816 | null |
Section: Order of precedence of group. When compounds contain more than one functional group, the order of precedence determines which groups are named with prefix or suffix forms. The table below shows common groups in decreasing order of precedence. The highest-precedence group takes the suffix, with all others takin... | Wikipedia - IUPAC nomenclature of organic chemistry - Order of precedence of group | 287 | 1,180 | null |
Section: Ions > Parent hydride cations. Simple cations formed by adding a hydron to a hydride of a halogen, chalcogen or pnictogen are named by adding the suffix "-onium" to the element's root: H4N+ is ammonium, H3O+ is oxonium, and H2F+ is fluoronium. Ammonium was adopted instead of nitronium, which commonly refers to... | Wikipedia - IUPAC nomenclature of organic chemistry - Ions > Parent hydride cations | 213 | 618 | null |
Article: Kaliapparat. A kaliapparat is a laboratory device invented in 1831 by Justus von Liebig (1803–1873) for the analysis of carbon in organic compounds. The device, made of glass, consists of a series of five bulbs connected and arranged in a triangular shape. To determine the carbon in an organic compound with a ... | Wikipedia - Kaliapparat - Summary | 265 | 1,236 | null |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.