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Lactone
Lactones are cyclic carboxylic esters. They are derived from the corresponding hydroxycarboxylic acids by esterification. They can be saturated or unsaturated. Lactones are formed by lactonization, the intramolecular esterification of the corresponding hydroxycarboxylic acids. Nomenclature Greek alphabet#Letters, Greek prefixes in alphabetical order indicate ring size. Lactones are usually named according to the precursor acid molecule (''aceto'' = 2 carbon atoms, ''propio'' = 3, ''butyro'' = 4, ''valero'' = 5, ''capro'' = 6, etc.), with a ''-lactone'' suffix and a Greek letter prefix that specifies the number of carbon atoms in the heterocycle — that is, the distance between the relevant -OH and the -COOH groups along said backbone. The first carbon atom after the carbon in the -COOH group on the parent compound is labelled α, the second will be labeled β, and so forth. Therefore, the prefixes also indicate the size of the lactone ring: α-lactone = 3-membered ring, β-lac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Caprolactone
ε-Caprolactone or simply caprolactone is a lactone (a cyclic ester) possessing a seven-membered ring. Its name is derived from caproic acid. This colorless liquid is miscible with most organic solvents and water. It was once produced on a large scale as a precursor to caprolactam. Production and uses Caprolactone is prepared industrially by Baeyer-Villiger oxidation of cyclohexanone with peracetic acid. Caprolactone is a monomer used in the production of highly specialised polymers. Ring-opening polymerization, for example, gives polycaprolactone. Another polymer is polyglecaprone, used as suture material in surgery. Reactions Although no longer economical, caprolactone was once produced as a precursor to caprolactam. Caprolactone is treated with ammonia at elevated temperatures to give the lactam: :(CH2)5CO2 + NH3 → (CH2)5C(O)NH + H2O Carbonylation of caprolactone gives, after hydrolysis, pimelic acid. The lactone ring is easily opened with nucleophiles including alcoho ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
δ-Valerolactone
δ-Valerolactone (delta-valerolactone) is a lactone used as a chemical intermediate in processes such as the production of polyesters. Natural occurrence δ-Valerolactone can be found in ''Aspalathus linearis Rooibos ( ; , ), or , is a broom (shrub), broom-like member of the plant family Fabaceae that grows in South Africa's Fynbos biome. The leaves are used to make a caffeine-free herbal tea, herbal infusion that has been popular in Southern Afri ...'' and '' Clerodendrum mandarinorum''. See also * γ-Valerolactone References Delta-lactones {{organic-compound-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acetolactone
Acetolactone (α-acetolactone) is an organic compound with formula . It is the smallest member of the lactone family but can also be described as the epoxide of ethenone. The compound was described in 1997 as a transient species in mass spectrometry experiments. Related compounds Although acetolactone itself has not been isolated in bulk, the related species bis(trifluoromethyl)acetolactone ((), which has increased electronic stabilisation due to its two trifluoromethyl groups, is known and has a half-life of 8 hours at 25 °C. This compound is prepared by photolysis Photodissociation, photolysis, photodecomposition, or photofragmentation is a chemical reaction in which molecules of a chemical compound are broken down by absorption of light or photons. It is defined as the interaction of one or more photons wi ... of bis(trifluoromethyl)malonyl peroxide. Other alpha lactones have been prepared. See also * α-Propiolactone * Oxalic anhydride References Alpha-lactones Su ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Macrolide
Macrolides are a class of mostly natural products with a large macrocyclic lactone ring to which one or more deoxy sugars, usually cladinose and desosamine, may be attached. Macrolides belong to the polyketide class of natural products. Some macrolides have antibiotic or antifungal activity and are used as pharmaceutical drugs. Rapamycin is also a macrolide and was originally developed as an antifungal, but has since been used as an immunosuppressant drug and is being investigated as a potential longevity therapeutic. Macrolides are a diverse group with many members of very different properties: * Macrolides with 14-, 15-, or 16-membered rings and two attached sugar molecules are antibiotics that bind to bacterial ribosomes, the key representative being erythromycin. The term "macrolide antibiotics" tend to refer to just this class. * Some macrolides with very large (20+ membered) rings are immunosuppresants, the prototypical one being rapamycin. * Some 23-membered ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carboxylic Ester
In chemistry, an ester is a chemical compound, compound derived from an acid (either organic or inorganic) in which the hydrogen atom (H) of at least one acidic hydroxyl group () of that acid is replaced by an organyl group (R). These compounds contain a Functional group#Groups containing oxygen , distinctive functional group. Analogues derived from oxygen replaced by other chalcogens belong to the ester category as well. According to some authors, organyl derivatives of acidic hydrogen of other acids are esters as well (e.g. amides), but not according to the IUPAC. Glycerides are fatty acid esters of glycerol; they are important in biology, being one of the main classes of lipids and comprising the bulk of animal fats and vegetable oils. Lactones are cyclic carboxylic esters; naturally occurring lactones are mainly 5- and 6-membered ring lactones. Lactones contribute to the aroma of fruits, butter, cheese, vegetables like celery and other foods. Esters can be formed from oxoa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Esterification
In chemistry, an ester is a compound derived from an acid (either organic or inorganic) in which the hydrogen atom (H) of at least one acidic hydroxyl group () of that acid is replaced by an organyl group (R). These compounds contain a distinctive functional group. Analogues derived from oxygen replaced by other chalcogens belong to the ester category as well. According to some authors, organyl derivatives of acidic hydrogen of other acids are esters as well (e.g. amides), but not according to the IUPAC. Glycerides are fatty acid esters of glycerol; they are important in biology, being one of the main classes of lipids and comprising the bulk of animal fats and vegetable oils. Lactones are cyclic carboxylic esters; naturally occurring lactones are mainly 5- and 6-membered ring lactones. Lactones contribute to the aroma of fruits, butter, cheese, vegetables like celery and other foods. Esters can be formed from oxoacids (e.g. esters of acetic acid, carbonic acid, sulfu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cardenolide
A cardenolide is a type of steroid. Many plants contain derivatives, collectively known as cardenolides, including many in the form of cardenolide glycosides (cardenolides that contain structural groups derived from sugars). Cardenolide glycosides are often toxic; specifically, they are cardiac arrest, heart-arresting. Cardenolides are toxic to animals through inhibition of the enzyme Na+/K+-ATPase, Na+/K+-ATPase, which is responsible for maintaining the sodium and Potassium in biology, potassium ion gradients across the cell membranes. Etymology The term derives from ''card-'' "heart" (from Greek language, Greek καρδία ''kardiā'') and the suffix , referring to the lactone ring with double bond at C17. Cardenolides are a class of steroids (or aglycones if viewed as cardiac glycoside constituents), and cardenolides are a subtype of this class (see Wikipedia:MeSH D04#MeSH D04.808.155 --- cardenolides, MeSH D codes list). Structure Cardenolides are C(23)-steroids with methyl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Macrocyclic
Macrocycles are often described as molecules and ions containing a ring of twelve or more atoms. Classical examples include the crown ethers, calixarenes, porphyrins, and cyclodextrins. Macrocycles describe a large, mature area of chemistry. Synthesis The formation of macrocycles by ring-closure is called macrocyclization. The central challenge to macrocyclization is that ring-closing reactions do not favor the formation of large rings. Instead, medium sized rings or polymers tend to form. Early macrocyclizations were achieved ketonic decarboxylations for the preparation of terpenoid macrocycles. So, while Ružička was able to produce various macrocycles, the yields were low. This kinetic problem can be addressed by using high-dilution reactions, whereby intramolecular processes are favored relative to polymerizations. Reactions amenable to high dilution include Dieckmann condensation and related based-induced reactions of esters with remote halides. Some macrocyclizat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bufadienolide
Bufadienolide is a chemical compound with steroid structure. Its derivatives are collectively known as bufadienolides, including many in the form of bufadienolide glycosides (bufadienolides that contain structural groups derived from sugars). These are a type of cardiac glycoside, the other being the cardenolide glycosides. Both bufadienolides and their glycosides are toxic; specifically, they can cause an atrioventricular block, bradycardia (slow heartbeat), ventricular tachycardia (a type of rapid heartbeat), and possibly lethal cardiac arrest. Etymology The term derives from the toad genus '' Bufo'' that contains bufadienolide glycosides, the suffix ''-adien-'' that refers to the two double bonds in the lactone ring, and the ending ''-olide'' that denotes the lactone structure. Consequently, related structures with only one double bond are called ''bufenolides'', and the saturated equivalent is ''bufanolide''. Classification According to MeSH, bufadienolides and bufan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
GBL Chemical Structure
GBL may refer to: Sports *Golden Baseball League, a defunct North American league * Greater Boston League, a defunct high school athletic conference in Massachusetts, United States * Greater Brisbane League, a baseball league in Queensland, Australia *Greek Basket League, in Greece Companies * GAMCO Investors, an American financial services company * GB Airways, a defunct British airline * Georgian Bay Line, a defunct American steamship operator *Groupe Bruxelles Lambert Groupe Bruxelles Lambert (GBL) is a Belgian holding company invested in multiple industries. It invests in both listed and private companies. Directed by Ian Gallienne, GBL had a net asset value of €22.5 billion and a market capitalisation of � ..., a Belgian holding company Other uses * Gainsborough Lea Road railway station, in England * Game Based Learning * Game Boy Light, a Japan-exclusive Nintendo handheld * Gamit language * ''gamma''-Butyrolactone * Garden-based learning * Glenn A. Black Laboratory of Ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lactic Acid
Lactic acid is an organic acid. It has the molecular formula C3H6O3. It is white in the solid state and it is miscible with water. When in the dissolved state, it forms a colorless solution. Production includes both artificial synthesis as well as natural sources. Lactic acid is an alpha-hydroxy acid (AHA) due to the presence of a hydroxyl group adjacent to the carboxyl group. It is used as a synthetic intermediate in many organic synthesis industries and in various biochemical industries. The conjugate base of lactic acid is called lactate (or the lactate anion). The name of the derived acyl group is lactoyl. In solution, it can ionize by a loss of a proton to produce the lactate ion . Compared to acetic acid, its p''K'' is 1 unit less, meaning lactic acid is ten times more acidic than acetic acid. This higher acidity is the consequence of the intramolecular hydrogen bonding between the α-hydroxyl and the carboxylate group. Lactic acid is chiral, consisting of two en ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lactide
Lactide is the lactone cyclic ester derived by multiple esterification between two (usually) or more molecules from lactic acid (2-hydroxypropionic acid) or other hydroxy carboxylic acid. They are designated as dilactides, trilactides, etc., according to the number of hydroxy acid residues. All lactides are colorless or white solids. The dilactide derived from lactic acid has the formula . This lactide has attracted interest because it is derived from abundant renewable resources and is the precursor to a biodegradable plastic. Stereoisomers The dilactide derived from lactic acid can exist in three different stereoisomeric forms. This complexity arises because lactic acid is chiral. These enantiomers do not racemize readily. All three stereoisomers undergo epimerisation in the presence of organic and inorganic bases in solution. Polymerization Lactide can be polymerized to polylactic acid (polylactide). Depending on the catalyst Catalysis () is the increase ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
