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DeMayo Reaction
The DeMayo reaction is a photochemical reaction in which the enol of a 1,3-diketone reacts with an alkene (or another species with a C=C bond) and the resulting cyclobutane ring undergoes a retro-aldol reaction to yield a 1,5-diketone: The net effect is to add the two carbon atoms in the C=C double bond between the two carbonyl groups of the diketone. It is thus useful in syntheses both as a relatively selective way to join two parts of a molecule and as a way to apply the more developed chemistry of 1,3-diketone synthesis to 1,5-diketones. The first part is a +2cycloaddition In organic chemistry, a cycloaddition is a chemical reaction in which "two or more Unsaturated hydrocarbon, unsaturated molecules (or parts of the same molecule) combine with the formation of a cyclic adduct in which there is a net reduction of th .... The ensuing retro-aldol cleavage is favored by the relative instability of the cyclobutane ring. References {{Reflist Organic reactions Name reactions< ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photochemical Reaction
Organic photochemistry encompasses organic reactions that are induced by the action of light. The absorption of ultraviolet light by organic molecules often leads to reactions. In the earliest days, sunlight was employed, while in more modern times ultraviolet lamps are employed. Organic photochemistry has proven to be a very useful synthetic tool. Complex organic products can be obtained simply. History Early examples were often uncovered by the observation of precipitates or color changes from samples that were exposed to sunlights. The first reported case was by Ciamician that sunlight converted santonin to a yellow photoproduct: An early example of a precipitate was the photodimerization of anthracene, characterized by Yulii Fedorovich Fritzsche and confirmed by Elbs. Similar observations focused on the dimerization of cinnamic acid to truxillic acid. Many photodimers are now recognized, e.g. pyrimidine dimer, thiophosgene, diamantane. Another example was uncovered by Egbe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Enol
In organic chemistry, alkenols (shortened to enols) are a type of reactive structure or intermediate in organic chemistry that is represented as an alkene ( olefin) with a hydroxyl group attached to one end of the alkene double bond (). The terms ''enol'' and ''alkenol'' are portmanteaus deriving from "-ene"/"alkene" and the "-ol" suffix indicating the hydroxyl group of alcohols, dropping the terminal "-e" of the first term. Generation of enols often involves removal of a hydrogen adjacent (α-) to the carbonyl group—i.e., deprotonation, its removal as a proton, . When this proton is not returned at the end of the stepwise process, the result is an anion termed an enolate (see images at right). The enolate structures shown are schematic; a more modern representation considers the molecular orbitals that are formed and occupied by electrons in the enolate. Similarly, generation of the enol often is accompanied by "trapping" or masking of the hydroxy group as an ether, such as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diketone
In organic chemistry, a dicarbonyl is a molecule containing two carbonyl () groups. Although this term could refer to any organic compound containing two carbonyl groups, it is used more specifically to describe molecules in which both carbonyls are in close enough proximity that their reactivity is changed, such as 1,2-, 1,3-, and 1,4-dicarbonyls. Their properties often differ from those of monocarbonyls, and so they are usually considered functional groups of their own. These compounds can have symmetrical or unsymmetrical substituents on each carbonyl, and may also be functionally symmetrical (dialdehydes, diketones, diesters, ''etc.'') or unsymmetrical (keto-esters, keto-acids, ''etc.''). 1,2-Dicarbonyls 1,2-Dialdehyde The only 1,2-dialdehyde is glyoxal, . Like many alkyldialdehydes, glyoxal is encountered almost exclusively as its hydrate and oligomers thereof. These derivatives often behave equivalently to the aldehydes since hydration is reversible. Glyoxal condenses re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alkene
In organic chemistry, an alkene is a hydrocarbon containing a carbon–carbon double bond. Alkene is often used as synonym of olefin, that is, any hydrocarbon containing one or more double bonds.H. Stephen Stoker (2015): General, Organic, and Biological Chemistry'. 1232 pages. Two general types of monoalkenes are distinguished: terminal and internal. Also called α-olefins, terminal alkenes are more useful. However, the International Union of Pure and Applied Chemistry (IUPAC) recommends using the name "alkene" only for acyclic hydrocarbons with just one double bond; alkadiene, alkatriene, etc., or polyene for acyclic hydrocarbons with two or more double bonds; cycloalkene, cycloalkadiene, etc. for cyclic ones; and "olefin" for the general class – cyclic or acyclic, with one or more double bonds. Acyclic alkenes, with only one double bond and no other functional groups (also known as mono-enes) form a homologous series of hydrocarbons with the general formula with '' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyclobutane
Cyclobutane is a cycloalkane and organic compound with the formula (CH2)4. Cyclobutane is a colourless gas and commercially available as a liquefied gas. Derivatives of cyclobutane are called cyclobutanes. Cyclobutane itself is of no commercial or biological significance, but more complex derivatives are important in biology and biotechnology. Structure The bond angles between carbon atoms are significantly strained and as such have lower bond energies than related linear or unstrained hydrocarbons, e.g. butane or cyclohexane. As such, cyclobutane is unstable above about 500 °C. The four carbon atoms in cyclobutane are not coplanar; instead the ring typically adopts a folded or "puckered" conformation. This implies that the C-C-C angle is less than 90°. One of the carbon atoms makes a 25° angle with the plane formed by the other three carbons. In this way some of the eclipsing interactions are reduced. The conformation is also known as a "butterfly". Equivalent p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aldol Reaction
The aldol reaction is a means of forming carbon–carbon bonds in organic chemistry. Discovered independently by the Russian chemist Alexander Borodin in 1869 and by the French chemist Charles-Adolphe Wurtz in 1872, the reaction combines two carbonyl compounds (the original experiments used aldehydes) to form a new β-hydroxy carbonyl compound. These products are known as ''aldols'', from the ''ald''ehyde + alcoh''ol'', a structural motif seen in many of the products. Aldol structural units are found in many important molecules, whether naturally occurring or synthetic. For example, the aldol reaction has been used in the large-scale production of the commodity chemical pentaerythritol and the synthesis of the heart disease drug Lipitor (atorvastatin, calcium salt). The aldol reaction unites two relatively simple molecules into a more complex one. Increased complexity arises because up to two new stereogenic centers (on the Alpha carbon, α- and β-carbon of the aldol adduct, mar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Demayo Reaction
The DeMayo reaction is a photochemical reaction in which the enol of a 1,3-diketone reacts with an alkene (or another species with a C=C bond) and the resulting cyclobutane ring undergoes a retro-aldol reaction to yield a 1,5-diketone: The net effect is to add the two carbon atoms in the C=C double bond between the two carbonyl groups of the diketone. It is thus useful in syntheses both as a relatively selective way to join two parts of a molecule and as a way to apply the more developed chemistry of 1,3-diketone synthesis to 1,5-diketones. The first part is a +2cycloaddition In organic chemistry, a cycloaddition is a chemical reaction in which "two or more Unsaturated hydrocarbon, unsaturated molecules (or parts of the same molecule) combine with the formation of a cyclic adduct in which there is a net reduction of th .... The ensuing retro-aldol cleavage is favored by the relative instability of the cyclobutane ring. References {{Reflist Organic reactions Name reactions< ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cycloaddition
In organic chemistry, a cycloaddition is a chemical reaction in which "two or more Unsaturated hydrocarbon, unsaturated molecules (or parts of the same molecule) combine with the formation of a cyclic adduct in which there is a net reduction of the Multiplicity (chemistry)#Molecules, bond multiplicity". The resulting reaction is a cyclization reaction. Many but not all cycloadditions are Concerted reaction, concerted and thus pericyclic. Nonconcerted cycloadditions are not pericyclic. As a class of addition reaction, cycloadditions permit carbon–carbon bond formation without the use of a nucleophile or electrophile. Cycloadditions can be described using two systems of notation. An older but still common notation is based on the size of linear arrangements of atoms in the reactants. It uses parentheses: where the variables are the numbers of linear atoms in each reactant. The product is a cycle of size . In this system, the standard Diels-Alder reaction is a (4 + 2)-cyc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organic Reactions
Organic reactions are chemical reactions involving organic compounds. The basic organic chemistry reaction types are addition reactions, elimination reactions, substitution reactions, pericyclic reactions, rearrangement reactions, photochemical reactions and redox reactions. In organic synthesis, organic reactions are used in the construction of new organic molecules. The production of many man-made chemicals such as drugs, plastics, food additives, fabrics depend on organic reactions. The oldest organic reactions are combustion of organic fuels and saponification of fats to make soap. Modern organic chemistry starts with the Wöhler synthesis in 1828. In the history of the Nobel Prize in Chemistry awards have been given for the invention of specific organic reactions such as the Grignard reaction in 1912, the Diels-Alder reaction in 1950, the Wittig reaction in 1979 and olefin metathesis in 2005. Classifications Organic chemistry has a strong tradition of naming a specific reac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
