Terms in this set (195)
A sulfone is a chemical compound containing a sulfonyl functional group attached to two carbon atoms.
A sulfoxide is a chemical compound containing a sulfinyl functional group attached to two carbon atoms.
Sulfonic acid usually refers to a member of the class of organosulfur compuonds with the general formula RS(=O)2−OH, where R is usually an alkyl or aryl.
Sulfinic acids are oxoacids of sulfur with the structure RSO(OH).
In chemistry, a disulfide usually refers to the structural unit composed of a linked pair of sulfur atoms. Disulfide usually refer to a chemical compound that contains a disulfide bond, such as diphenyl disulfide, C6H5S-SC6H5.
A sulfide is an anion of sulfur in its lowest oxidation number of −2, S2−.
Sulfide is also a slightly archaic term for thioether.
In organic chemistry, "sulfide" usually refers to the linkage C−S−C, although the term thioether is less ambiguous. For example, the thioether dimethyl sulfide is CH3−S−CH3.
Occasionally, the term sulfide refers to molecules containing the −SH functional group. For example, methyl sulfide can mean CH3−SH. The preferred descriptor for such SH-containing compounds is thiol or mercaptan, i.e. methanethiol, or methyl mercaptan.
In organic chemistry, a thiol is a organosulfur compound that contains a carbon-bonded sulfhydryl (R−SH) group (where R represents an alkane, alkene, or other carbon-containing moiety).
Thiocyanate (also known as rhodanide) is the anion [SCN]¯. It is the conjugate base of thiocyanic acid. Organic compounds containing the functional group SCN are also called thiocyanates.
Isothiocyanate is the functional group -N=C=S, formed by substituting sulfur for oxygen in the isocyanate group.
Thioketones (also known as thiones or thiocarbonyls) are organic compounds related to conventional ketones. Instead of the formula R2C=O, thioketones have the formula R2C=S. Unhindered thioketones are typically unstable; such compounds tend to form polymers or rings.
A thial or thioaldehyde is a functional group in organic chemistry which is similar to an aldehyde, RC(=O)H, in which a sulfur (S) atom replaces the oxygen (O) atom of the aldehyde (R represents an alkyl or aryl group). Thioaldehydes are even more reactive than the thioketones. Unhindered thioaldehydes are generally unstable — for example, thioformaldehyde, H2C=S, condenses to the cyclic trimer 1,3,5-trithiane. With sufficient steric bulk, however, stable thioaldehydes can be isolated.
In organic chemistry, an imide is a functional group consisting of two carbonyl groups bound to nitrogen. These compounds are structurally related to acid anhydrides.
Azo compounds are compounds bearing the functional group R−N=N−R', in which R and R' can be either aryl or alkyl.
In organic compounds cyanate is the functional group −O−C≡N.
Isocyanate is the functional group of atoms −N=C=O, not to be confused with the cyanate functional group which is arranged as −O−C≡N or with isocyanide, R−N≡C.
A nitrile is any organic compound that has a −C≡N functional group. The −C≡N group is called a nitrile group. The prefix cyano- is used in chemical nomenclature to indicate the presence of a -CN group in a molecule.
An isocyanide (also called isonitrile or carbylamine) is an organic compound with the functional group -N≡C. It is the isomer of the related cyanide (-C≡N).
A cyanide is a chemical compound that contains the cyano group (C≡N). Most commonly, cyanides refers to salts of the anion CN¯.
quaternary ammonium cation
Quaternary ammonium cations, also known as quats, are positively charged polyatomic ions of the structure NR4+, R being an alkyl group or an aryl group. Unlike the ammonium ion (NH4+) and the primary, secondary, or tertiary ammonium cations, the quaternary ammonium cations are permanently charged, independent of the pH of their solution. Quaternary ammonium salts or quaternary ammonium compounds (called quaternary amines in oilfield parlance) are salts of quaternary ammonium cations with an anion.
An imine (pronounced /ɨˈmiːn/ or /ˈɪmɪn/) is a functional group or chemical compound containing a carbon-nitrogen double bond, with the nitrogen attached to a hydrogen atom (H) or an organic group. The carbon has two additional single bonds.
In organic chemistry, nitrites are esters of nitrous acid and contain the nitrosooxy functional group. They possess the general formula RONO, where R is an aryl or alkyl group.
Nitro compounds are organic compounds that contain one or more nitro functional groups (-NO2). They are often highly explosive, especially when the compound contains more than one nitro group and is impure.
Nitroso refers to a functional group in organic chemistry which has the general formula RNO. Nitroso compounds are a class of organic compounds containing the nitroso functional group, R−N=O.
Phosphine (IUPAC name: phosphane) is the compound with the chemical formula PH3. Phosphines are also a group of organophosphorus compounds with the formula R3P (R = organic derivative).
In organic chemistry, a phosphate, or organophosphate, is an ester of phosphoric acid.
phosphoric acid functional group
Phosphonates or phosphonic acids are organic compounds containing C−PO(OR)2 or C−PO(OH)2 groups (where R=alkyl, aryl).
Phosphonites are organophosphorus compounds with the formula P(OR)2R. They are derivivatives of phosphonous acid.
A phosphite ester or organophosphite is a type of chemical compound with the general structure P(OR)3. Phosphite esters can be considered as esters of phosphorous acid, H3PO3.
Phosphinates are organophosphorus compounds with the formula O=P(OR)R2.
Phosphine oxides are organophosphorus compounds with the formula OPR3, where R = alkyl or aryl. They are considered to be the most stable organophosphorus compounds, triphenylphosphine oxide and trimethylphosphine oxide decomposing only above 450 °C.
Mesitylene or 1,3,5-trimethylbenzene is an aromatic hydrocarbon with three methyl substituents attached to the benzene ring.
Mesityl group (Mes) is a functional group derived from the compound mesitylene.
Annulenes are completely conjugated monocyclic hydrocarbons.
Maleic acid (C4H4O4, MW=116.07) is an organic compound that is a dicarboxylic acid, a molecule with two carboxyl groups. Maleic acid is the cis isomer of butenedioic acid, whereas fumaric acid is the trans isomer.
Fumaric acid or trans-butenedioic acid is the chemical compound with the formula HO2CCH=CHCO2H (C4H4O4, MW=116.07). This white crystalline compound is one of two isomeric unsaturated dicarboxylic acids, the other being maleic acid, wherein the carboxylic acid groups are cis [= (Z)]. It has a fruit-like taste. The salts and esters of fumaric acid are known as fumarates.
In chemistry, topicity is the stereochemical relationship of substituents relative to the structure to which they are attached. Depending on the relationship, such groups can be heterotopic, homotopic, enantiotopic, or diastereotopic.
Homotopic groups in a chemical compound are equivalent groups. Two groups A and B are homotopic if the molecule remains the same (including stereochemically) when the groups are interchanged with the remaining parts of the molecule fixed. Homotopic atoms are always identical, in any environment.
The stereochemical term enantiotopic refers to the relationship between two groups in a molecule which, if one or the other were replaced, would generate a chiral compound. The two possible compounds resulting from that replacement would be enantiomers.
The stereochemical term diastereotopic refers to the relationship between two groups in a molecule which, if replaced, would generate compounds that are diastereomers. Diastereotopic groups are often, but not always, identical groups attached to the same atom in a molecule containing at least one chiral center.
Diastereotopic groups also arise in achiral molecules. The term diastereotopic is also applied to identical groups attached to the same end of an alkene moiety which, if replaced, would generate geometric isomers.
pro-R and pro-S
If two identical substituents of a prochiral center are attached to an sp3-hybridized atom, the descriptors pro-R and pro-S are used to distinguish between the two. Promoting the pro-R substituent to higher priority than the identical alternative would result in an R chirality center at the original sp3-hybridized atom, and vice versa.
In stereochemistry, prochiral molecules are those that can be converted from achiral to chiral in a single step.
re and si faces
A trigonal planar sp2-hybridized atom can be converted to a chiral center when a substituent is added to the re face or si face of the molecule. These faces are labelled re if the substituents at the trigonal atom are disposed in decreasing priority order in a clockwise order, and si if the priorities decrease in counter-clockwise order; but the designation of the resulting chiral centre as R or S depends on the priority of the incoming group.
Camphor (C10H16O, MW=152.23) is a waxy, white or transparent solid with a strong, aromatic odor.
Norcamphor is a camphor derivative with the three methyl groups replaced by hydrogen.
Camphorsulfonic acid (C10H16O4S, MW=232.3), sometimes abbreviated CSA or 10-CSA, is a organosulfur compound. Like typical sulfonic acids, it is a relatively strong acid that exists as a colourless solid that is soluble in organic solvents.
preparation of camphorsulfonic acid
This compound is commercially available. It can be prepared by sulfonation camphor with sulfuric acid and acetic anhydride.
Pyrrolidine, also known as tetrahydropyrrole, azolidine, or azacyclopentane, is an organic compound with the molecular formula C4H9N (MW=71.11). It is a cyclic amine with a five-membered heterocycle containing four carbon atoms and one nitrogen atom. It is a clear liquid with an unpleasant ammonia-like odor.
In organic chemistry, pyrrolidine is used to activate ketones toward nucleophilic addition by formation of the imine.
2-Oxazolidone or 2-oxazolidinone is a heterocyclic organic compound containing both nitrogen and oxygen in a 5-membered ring.
The Wolff rearrangement is a rearrangement reaction converting a α-diazo-ketone into a ketene.
mechanism of Wolff rearrangement
Nitrogen extrusion and the 1,2-shift can occur either in a concerted manner or stepwise via a carbene intermediate.
3-Methylenecyclopropene is a hydrocarbon with chemical formula C4H4 and CAS number 4095-06-1. It dimerizes or polymerizes readily, but is more stable than cyclobutadiene.
Methylene is a chemical species in which a carbon atom is bonded to two hydrogen atoms. Three different possibilities present themselves:
1. the >CH2 (methanediyl) substituent group: e.g., dichloromethane (CH2Cl2, also known as methylene chloride).
2. the =CH2 (methylidene) substituent group: e.g., methylenecyclopropene.
3. the :CH2 molecule: A carbene known as methylene.
Methylene groups in a chain or ring contribute to its size and lipophilicity. Methylene was also the old original name for methanol.
Piperidine Azinane after the Hantzsch-Widman nomenclature) is an organic compound with the molecular formula (CH2)5NH.
4-Piperidinone (other names: Piperidin-4-one, 4-Piperidone, Azinanone, Azinan-4-one) is a derivative of piperidine with the molecular formula C5H9NO (MW=99.13) and CAS number 41661-47-6.
Diacetyl (IUPAC systematic name: butanedione or 2,3-butanedione) is a natural byproduct of fermentation. It is a vicinal diketone (two C=O groups, side-by-side) with the molecular formula C4H6O2 (MW=86.0892) and CAS number 431-03-8.
Hexane-2,5-dione, C6H10O2 (MW=114.1438, CAS number: 110-13-4), is a diketone and a toxic metabolite of hexane.
Lysine (abbreviated as Lys or K) (2,6-diaminohexanoic acid) is an α-amino acid with the chemical formula HO2CCH(NH2)[(CH2)4NH2] (MW=146.19). It is an essential amino acid, which means that the human body cannot synthesize it. Its codons are AAA and AAG.
Acetylacetone (IUPAC name: Pentane-2,4-dione) is an organic compound with molecular formula C5H8O2 (MW=100.13) and CAS number 123-54-6. This diketone is formally named 2,4-pentanedione. It is a precursor to acetylacetonate (acac), a common bidentate ligand. It is also a building block for the synthesis of heterocyclic compounds.
reaction of diazomethane
Diazomethane is an extremely versatile reagent for the preparation of both carbon-carbon and carbon-heteroatom bonds. It is one of the most common methylating reagents for the preparation of methyl esters from the corresponding carboxylic acids. Additionally, diazomethane has found extensive application in the alkylation of phenols, enols, and heteroatoms such as nitrogen and sulfur. Diazomethane has also been used in: cycloalkanone ring expansion, preparation of α-diazo ketones, and pyrazoline formation (1,3-dipolar cycloaddition), and Pd-catalyzed cyclopropanation (a carbene source).
Diazomethane is the chemical compound CH2N2. It is one of the most common diazo compounds. In the pure form at room temperature, it is a famously explosive yellow gas, but it is almost universally used as a solution in diethyl ether. The compound is a popular methylating agent in the laboratory, but it is too hazardous to be employed on a technical scale without special precautions.
Trimethylsilyldiazomethane [IUPAC name: (Diazomethyl)trimethylsilane], (CH3)3SiCHN2, is a diazo compound widely used as a less-explosive replacement for diazomethane.
Triphenylmethane, or triphenyl methane, is the hydrocarbon with the formula (C6H5)3CH. This colorless solid is soluble in nonpolar organic solvents and not in water. Triphenylmethane has the basic skeleton of many synthetic dyes called triarylmethane dyes, many of them are pH indicators, and some display fluorescence.
A trityl group in organic chemistry is a triphenylmethyl group Ph3C−.
The pKa of the hydrogen on the central carbon is around 31. Triphenylmethane is significantly more acidic than most other hydrocarbons because the planar trityl anion is stabilized by extensive delocalization over three phenyl rings.
4-Dimethylaminopyridine (DMAP) is a derivative of pyridine with the chemical formula (CH3)2NC5H4N. This colourless solid is a useful nucleophilic catalyst for a variety of reactions such as esterifications with anhydrides, the Baylis-Hillman reaction, hydrosilylations, tritylation, the Steglich rearrangement, Staudinger synthesis of β-lactams and many more. Chiral DMAP analogues are used in kinetic resolution experiments of mainly secondary alcohols and Evans auxiliary type amides.
Norbornane (also known as bicyclo[2.2.1]heptane) is an organic compound and a saturated hydrocarbon with chemical formula C7H12.
Solvolysis is a special type of nucleophilic substitution or elimination reaction where the nucleophile is a solvent molecule.
For certain nucleophiles, there are specific terms for the type of solvolysis reaction. For water, the term is hydrolysis; for alcohols, it is alcoholysis; for ammonia, it is ammonolysis; for glycols, glycolysis; for amines, aminolysis.
A sulfonium ion, also known as sulphonium ion or sulfanium ion, is a positively charged ion (a "cation") featuring three organic substituents attached to sulfur. They have the formula [SR3]+. Together with their negatively charged counterpart, the anion, the compounds are called sulfonium salts.
Sulfanilic acid (4-aminobenzene sulfonic acid) is a colourless crystalline solid produced from sulfonation of aniline.
It readily forms diazo compounds and is used to make dyes and sulpha drugs.
Sulphanilic acid exists as a zwitterion, and has an unusually high melting point. It is used as a standard in combustion analysis.
tert-Butylhydroquinone (TBHQ, tertiary butylhydroquinone) is an aromatic organic compound which is a type of phenol. It is a derivative of hydroquinone, substituted with tert-butyl group.
TBHQ is a highly effective antioxidant. In foods, it is used as a preservative for unsaturated vegetable oils and many edible animal fats. It does not cause discoloration even in the presence of iron, and does not change flavor or odor of the material to which it is added.
α-Methylstyrene (AMS) is a chemical intermediate used in the manufacture of plasticizers, resins and polymers. It is a co-product formed in a variation of the cumene process.
Cumene hydroperoxide is an intermediate in the cumene process. Its formula is C6H5C(CH3)2OOH.
Acetophenone is the organic compound with the formula C6H5C(O)CH3. It is the simplest aromatic ketone. This colourless, viscous liquid is a precursor to useful resins and fragrances.
Cumene is the common name for isopropylbenzene, an organic compound that is an aromatic hydrocarbon. It is a constituent of crude oil and refined fuels. It is a flammable colorless liquid that has a boiling point of 152 °C. Nearly all the cumene that is produced as a pure compound on an industrial scale is converted to cumene hydroperoxide, which is an intermediate in the synthesis of other industrially important chemicals such as phenol and acetone.
The Cumene process (Cumene-phenol process, Hock process) is an industrial process for developing phenol and acetone from benzene and propylene. The term stems from cumene (isopropyl benzene), the intermediate material during the process. It was invented by Heinrich Hock in 1944.
This process converts two relatively cheap starting materials, benzene and propylene, into two more valuable ones, phenol and acetone. Other reactants required are oxygen from air and small amounts of a radical initiator. Most of the worldwide production of phenol and acetone is now based on this method.
Methylcyclopentane is an organic compound with the chemical formula CH3C5H9. It is one of the important benzene precursors that can react in refinery processes to form benzene.
Triphenylmethyl chloride or trityl chloride is a white solid with the chemical formula C19H15Cl. It is an alkyl halide, sometimes used to introduce the trityl protecting group.
Triphenylmethyl chloride is commercially available. It may be prepared by the reaction of triphenylmethanol with acetyl chloride, or by the Friedel-Crafts alkylation of benzene with carbon tetrachloride to give the trityl chloride-aluminium chloride adduct, which is then hydrolyzed.
Triphenylmethylsodium may can be prepared from trityl chloride and sodium. Reaction with silver hexafluorophosphate gives triphenylmethyl hexafluorophosphate.
The triphenylmethyl radical is a persistent radical and the first-ever radical described in organic chemistry. It can be prepared by homolysis of triphenylmethyl chloride 1 by a metal like silver or zinc in benzene or diethyl ether. The radical 2 forms a chemical equilibrium with the quinoid type dimer 3. In benzene the concentration of the radical is 2%.
N-Oxoammonium salts in organic chemistry are a class of organic compounds sharing a functional group with the general structure R1R2N+=O X¯ where X¯ is the counterion. The N-oxoammonium salt from TEMPO is used for oxidation of alcohols to carbonyl groups.
Potassium peroxymonosulfate (also known as MPS, potassium monopersulfate, and the trade names Caroat and Oxone, CAS number: 10361-76-9) is widely used as an oxidizing agent. It is the potassium salt of peroxymonosulfuric acid.
The potassium salt is marketed by two companies: Evonik (formerly Degussa) under the tradename Caroat and DuPont under the tradename Oxone, tradenames which are now part of standard chemistry vocabulary. It is a component of a triple salt with the formula 2KHSO5•KHSO4•K2SO4 (CAS number: 37222-66-5).
reactions of oxone
Oxone is a versatile oxidant. It oxidizes aldehydes to carboxylic acids; in the presence of alcoholic solvents, the esters may be obtained. Internal alkenes may be cleaved to two carboxylic acids, while terminal alkenes may be epoxidized. Thioethers give sulfones, tertiary amines give amine oxides, and phosphines give phosphine oxides.
It will also oxidize a thioether to a sulfone with 2 equivalents. With one equivalent the reaction converting sulfide to sulfoxide is much faster than that of sulfoxide to sulfone, so the reaction can conveniently be stopped at that stage if so desired.
IBX acid or 2-Iodoxybenzoic acid is an organic compound used in organic synthesis as an oxidizing agent. This Periodinane is especially suited to oxidize alcohols to aldehydes.
reaction mechanism of IBX
The reaction mechanism for an oxidation of an alcohol to an aldehyde according the so-called hypervalent twisting mechanism involves a ligand exchange reaction replacing the hydroxyl group by the alcohol followed by a twist and an elimination reaction.
oxidative cleavage by IBX
The use of IBX in combination with DMSO was demonstrated in oxidative cleavage of vicinal diols to ketones.
α-hydroxylation by IBX
IBX is able to hydroxylate ketone compounds with in α-position under mild conditions. This method could be extended to β-keto esters.
A hydroxy ketone in organic chemistry is a functional group consisting of a ketone flanked by a hydroxyl group. In the two main classes the hydroxyl group can be placed in the alpha position (an alpha-hydroxy ketone RCR'(OH)(CO)R) or in the beta position (a beta-hydroxy ketone, RCR'(OH)CR2(CO)R).
Anthranilic acid is the organic compound with the formula C6H4(NH2)COOH. This amino acid is white solid when pure, although commercial samples may appear yellow.
Anthranilic acid can be used in organic synthesis to generate the benzyne intermediate.
preparation of IBX
The IBX acid is prepared from 2-iodobenzoic acid, potassium bromate and sulfuric acid.
Frigerio and co-workers have also demonstrated, in 1999 that potassium bromate may be replaced by commercially available Oxone.
The acrylate ion (CH2=CHCOO−) is the ion of acrylic acid. Acrylates are the salts and esters of acrylic acid. They are also known as propenoates (since acrylic acid is also known as 2-propenoic acid).
Sodium hypochlorite is a chemical compound with the formula NaClO. Sodium hypochlorite solution, commonly known as bleach, is frequently used as a disinfectant or a bleaching agent.
Hypochlorous acid is a weak acid with the chemical formula HClO. In the swimming pool industry, hypochlorous acid is referred to as HOCl. It forms when chlorine dissolves in water. It cannot be isolated in pure form due to rapid equilibration with its precursor (see below). HClO is an oxidizer, and in its sodium form Sodium hypochlorite, NaClO, or its calcium form Calcium hypochlorite, is used as a bleach, a deodorant, and a disinfectant.
The Pfitzner-Moffatt oxidation, sometimes referred to as simply the Moffatt oxidation, is a chemical reaction which describes the oxidation of primary and secondary alcohols by dimethyl sulfoxide (DMSO) activated with a carbodiimide, such as dicyclohexylcarbodiimide (DCC). The resulting alkoxysulfonium ylide rearranges to generate aldehydes and ketones, respectively.
meta-Chloroperoxybenzoic acid (m-CPBA) is a peroxycarboxylic acid used widely as an oxidant in organic synthesis. mCPBA is often preferred to other peroxy acids because of its relative ease of handling.
The main areas of use are the conversion of ketones to esters (Baeyer-Villiger oxidation), epoxidation of alkenes (Prilezhaev reaction), oxidation of sulfides to sulfoxides and sulfones, and oxidation of amines to produce amine oxides.
Trichloroacetic acid (also known as trichloroethanoic acid, TCCA) is an analogue of acetic acid in which the three hydrogen atoms of the methyl group have all been replaced by chlorine atoms.
Trichloroacetic acid is widely used in biochemistry for the precipitation of macromolecules such as proteins, DNA and RNA.
α,β-Unsaturated Carbonyl from Saturated Alcohol and Carbonyl by IBX
Nicolaou and co-workers developed a method for the oxidation of alcohols, aldehydes, and ketones that provides α,β-unsaturated carbonyl compounds using IBX at elevated temperatures.
Oxidation of Phenols to o-Quinones by IBX
A regioselective oxidation of phenols to o-quinones using IBX was reported by Pettus and co-workers. D'Ischia and co-workers have now expanded the scope of this method to estrogens and several other phenolic compounds using a low temperature reductive procedure under homogeneous phase conditions.
Oxalyl chloride or ethanedioyl dichloride is a chemical compound with the formula (COCl)2. This colourless, sharp-smelling liquid, the diacid chloride of oxalic acid, is a useful reagent in organic synthesis. It can be prepared by treating oxalic acid with phosphorus pentachloride.
Dimethyl sulfoxide (DMSO) is the organosulfur compound with the formula (CH3)2SO. This colorless liquid is an important polar aprotic solvent that dissolves both polar and nonpolar compounds and is miscible in a wide range of organic solvents as well as water. It penetrates the skin very readily, giving it the unusual property of being secreted onto the surface of the tongue after contact with the skin and causing a garlic-like taste in the mouth.
The Swern oxidation, named after Daniel Swern, is a chemical reaction whereby a primary or secondary alcohol is oxidized to an aldehyde or ketone using oxalyl chloride, dimethyl sulfoxide (DMSO) and an organic base, such as triethylamine. The reaction is known for its mild character and wide tolerance of functional groups.
mechanism of Swern oxidation
preparation of trifluoroacetic anhydride
Trifluoroacetic anhydride may be prepared from trifluoroacetic acid by dehydrating with excess α-halogenated acid chlorides. For example, with dichloroacetyl chloride:
2 CF3COOH + Cl2CHCOCl → (CF3CO)2O + Cl2CHCOOH + HCl
Dicyclohexylurea is an organic compound, specifically, a urea. It is the byproduct of the reaction of dicyclohexylcarbodiimide with amines or alcohols.
preparation of dicyclohexylurea
Dicyclohexylurea may be prepared by the reaction of cyclohexylamine and S,S-dimethyl dithiocarbonate.
ortho, meta, and para substitution
* In ortho-substitution, two substituents occupy positions next to each other, which may be numbered 1 and 2. In the diagram, these positions are marked R and ortho.
* In meta-substitution the substituents occupy positions 1 and 3 (corresponding to R and meta in the diagram).
* In para-substitution, the substituents occupy the opposite ends (positions 1 and 4, corresponding to R and para in the diagram).
Ipso-substitution describes two substituents sharing the same ring position in an intermediate compound in an electrophilic aromatic substitution.
Meso-substitution refers to the substituents occupying a benzylic position. It is observed in compounds such as calixarenes and acridines.
Peri-substitution occurs in naphthalenes for substituents at the 1 and 8 positions.
Diazonium compounds or diazonium salts are a group of organic compounds sharing a common functional group R−N2+ X- where R can be any organic residue such alkyl or aryl and X is an inorganic or organic anion such as a halogen.
Triazene, also known as triazanylene, is an unsaturated inorganic compound having the chemical formula N3H3. It has one double bond, and is the second simplest member of the azene class of hydronitrogen compounds, and is not found in nature.
Triazene is also the name given to the functional group consisting of an amine directly bonding to an azo group, i.e. with the linkage R1R2N−N=NR3 where R1, R2 and R3 are substituents. The functional group is also called a diazoamino group (but only one of the two substituents R1 and R3 may be hydrogen) because it is related to a diazo group.
Nitryl is the nitrogen dioxide (NO2) moiety when it occurs in a larger compound. Examples include nitryl fluoride (NO2F) and nitryl chloride (NO2Cl).
Like nitrogen dioxide, the nitryl moiety contains a nitrogen with two bonds to the two oxygen atoms, and a third bond shared equally between the nitrogen and the two oxygen atoms.
Nitrogen dioxide is the chemical compound with the formula NO2. One of several nitrogen oxides, NO2 is an intermediate in the industrial synthesis of nitric acid, millions of tons of which are produced each year. This reddish-brown toxic gas has a characteristic sharp, biting odor and is a prominent air pollutant. Nitrogen dioxide is a paramagnetic bent molecule with C2v point group symmetry.
The nitronium ion, or sometimes the nitryl ion, NO2+, is a generally unstable cation created by the removal of an electron from the paramagnetic nitrogen dioxide molecule, or the protonation of nitric acid.
generation of nitronium ion
The ion is generated in situ for this purpose by mixing sulfuric acid and nitric acid according to the equilibrium:
2 H2SO4 + HNO3 → 2 HSO4− + NO2+ + H3O+
Acetyl nitrate is a chemical compound with the formula of CH3COONO2 (CAS: 591-09-3).
Another useful medium for nitration is a solution prepared by dissolving nitric acid in acetic anhydride, which generates acetyl nitrate. This reagent tends to give high ortho:para ratios for some nitrations.
Copper(II) nitrate is the chemical compound with the formula Cu(NO3)2. Commonly referred to simply as copper nitrate, the anhydrous form is a blue, crystalline solid. Hydrated forms of copper nitrate, also blue, are commonly used in school laboratories to demonstrate chemical voltaic cell reactions.
Hydrated copper nitrate absorbed onto clay affords a reagent called "Claycop". The resulting blue-colored clay is used as a slurry, for example for the oxidation of thiols to disulfides. Claycop is also used to convert dithioacetals to carbonyls. A related reagent based on Montmorillonite has proven useful for the nitration of aromatic compounds.
Hydrated copper nitrate absorbed onto clay affords a reagent called "Claycop"
aromatic nitration by nitronium salts
Salts containing the nitronium ion can be prepared and are reactive nitrating agents. Nitronium tetrafluoroborate has been used most frequently:
Phenylacetic acid (abr. PAA and synonyms are: α-toluic acid, benzeneacetic acid, alpha tolylic acid, 2-phenylacetic acid) is an organic compound containing a phenyl functional group and a carboxylic acid functional group.
preparation of phenylacetic acid
This compound may be prepared by the hydrolysis of benzyl cyanide:
Anthracene is a solid polycyclic aromatic hydrocarbon consisting of three fused benzene rings. It is a component of coal-tar
Choline is a water-soluble essential nutrient. It is usually grouped within the B-complex vitamins. Choline generally refers to the various quaternary ammonium salts containing the N,N,N-trimethylethanolammonium cation.
The chemical compound acetylcholine (often abbreviated ACh) is a neurotransmitter in both the peripheral nervous system (PNS) and central nervous system (CNS) in many organisms including humans. Acetylcholine is one of many neurotransmitters in the autonomic nervous system (ANS) and the only neurotransmitter used in the motor division of the somatic nervous system. (Sensory neurons use glutamate and various peptides at their synapses.) Acetylcholine is also the principal neurotransmitter in all autonomic ganglia.
Chlorpyrifos (IUPAC name: O,O-diethyl O-3,5,6-trichloropyridin-2-yl phosphorothioate) is a crystalline organophosphate insecticide that inhibits acetylcholinesterase and is used to control insect pests.
NBS and NCS and halogenating agents
N -Bromosuccinimide (NBS) and N -chlorosuccinimide (NCS) are alternative halogenating agents. Activated aromatics, such as 1,2,4-trimethoxybenzene, are brominated by NBS at room temperature. Both NCS and NBS can halogenate moderately active aromatics in nonpolar solvents by using HCl16 or HClO4 as a catalyst.
pyridinium bromide perbromide
It is is a needle crystal solid with red-brown, and soluble in dichloromethane and glacial acetic acid. It would is decomposed in a moist air.
Uses: It is a convenient and easy to handle brominating agent.
Tetrabutylammonium tribromide is a reagent used in organic chemistry as a source of bromine. Its melting point ranges from 103-104 degrees Celsius.
A hypohalite is an oxyanion containing a halogen in oxidation state +1.
Halogenation catalyzed by Mercuric Acetate or Trifluoroacetate
Halogenations are strongly catalyzed by mercuric acetate or trifluoroacetate. These conditions generate acyl hypohalites, which are the active halogenating agents. The trifluoroacetyl hypohalites are very reactive reagents. Even nitrobenzene, for example, is readily brominated by trifluoroacetyl hypobromite.
In medicinal chemistry, bioisosteres are substituents or groups with similar physical or chemical properties which produce broadly similar biological properties to a chemical compound. In drug design, the purpose of exchanging one bioisostere for another is to enhance the desired biological or physical properties of a compound without making significant changes in chemical structure. The main use of this term and it techniques are related to pharmaceutical sciences. Bioisosterism is used to attenuate toxicity or modify the activity of the lead compound, and may alter the metabolism of the lead.
Chloranil is a quinone with the molecular formula C6Cl4O2. It is used as a reagent for the dehydrogenation of hydroaromatic compounds. It can be used as one-electron oxidation reagent to remove one electron from a substrate.
Azobisisobutyronitrile is a compound often used as a foamer in plastics and rubber and as a radical initiator. It is commonly known as AIBN.
decomposition of AIBN
Benzoyl peroxide is an organic compound in the peroxide family. It consists of two benzoyl groups bridged by a peroxide link. Its structural formula is [C6H5C(O)]2O2.
benzoyl peroxide as radical initiator
A ketyl group in organic chemistry is an anion radical with the general structure C-O. in which an oxygen radical is bonded directly to carbon. This radical is very unstable and appears in chemical reactions as a reactive intermediate. Another mesomeric structure has the radical position on carbon and the negative charge on oxygen.
Ketyls can be formed as radical anions by one-electron reduction of carbonyls with alkali metals.
ketyl used in distilling solvent
Ketyl radicals can be found in the use of sodium/benzophenone as a desiccant in distilling solvents. Sodium reduces benzophenone to the soluble ketyl radical, which reacts quickly with the water and oxygen dissolved in the solvent. The deep blue coloration qualitatively indicates dry, oxygen-free conditions.
Manganese(III) acetate is an inorganic compound that is used as a reagent in organic synthesis. Like the related chromium and iron compounds, it is an oxo-centred coordination complex. It is usually prepared from potassium permanganate and manganeous acetate in acetic acid.
Mn(OAc)3 in lactonization
manganese(III) acetate is most widely used to add H−CH2CO2H across double bonds and is useful in lactonization reactions.
Mn(OAc)3: Oxidative Cyclizations of Unsaturated Systems with Active Methylene Compounds
2,3-Dichloro-5,6-dicyano-1,4-benzoquinone (or DDQ) is the chemical reagent with formula C8Cl2N2O2. This oxidant is useful for the dehydrogenation of alcohols, phenols and steroid ketones in organic chemistry. DDQ decomposes in water, but will stay stable in aqueous mineral acid.
DDQ can react with water and give off hydrogen cyanide (HCN), which is highly toxic. Storage should be in dry area. Low temperature and weak acid environment can increase the stability of DDQ.
mechanism of dehydrogenation by DDQ
The simplified mechanism of dehydrogenation with DDQ involves the transfer of a hydride from the hydrocarbon molecule to the quinone oxygen, followed by the transfer of a proton to the phenolate ion. Thus, DDQ is reduced to hydroquinone.
The calicheamicins are a class of enediyne antibiotics derived from the bacterium Micromonospora echinospora, with calicheamicin γ1 being the most notable. It was isolated originally from a rock collected by a Scripps Research Institute chemist while hiking in Waco, Texas. It is extremely toxic to all cells and its analogues have been used as targeted therapy against cancer. Calicheamicin γ1 and the related enediyne esperamicin are the two most potent antitumor agents known.
The Bergman cyclization or Bergman reaction or Bergman cycloaromatization is an organic reaction and more specifically a rearrangement reaction taking place when an enediyne is heated in presence of a suitable hydrogen donor. It is named for the American chemist Robert George Bergman (b. 1942). The reaction product is a derivative of benzene.
An enyne is a functional group in organic chemistry consisting of a conjugated alkyne and alkene group.
mechansm of Bergman cyclization
Bergman cyclization of enyne moiety incorporated into a 10-membered hydrocarbon ring
When the enyne moiety is incorporated into a 10-membered hydrocarbon ring (e.g. cyclodeca-3-ene-1,5-diyne) the reaction, taking advantage of increased ring strain in the reactant, is possible at the much lower temperature of 37°C.
generation of carbene from diazoalkane
Most commonly, carbenes are generated from diazoalkanes, via photolytic, thermal, or transition metal-catalyzed routes. Catalysts typically feature rhodium and copper. The Bamford-Stevens reaction gives carbenes in aprotic solvents and carbenium ions in protic solvents.
In chemistry, a nitrene (R-N:) is the nitrogen analogue of a carbene. The nitrogen atom has only 6 valence electrons and is therefore considered an electrophile. A nitrene is a reactive intermediate and is involved is many chemical reactions.
formation of nitrene
Because nitrenes are so reactive, they are not isolated. Instead, they are formed as reactive intermediates during a reaction. There are two common ways to generate nitrenes:
1. from azides by thermolysis or photolysis, with expulsion of nitrogen gas. This method is analogous to the formation of carbenes from diazo compounds;
2. from isocyanates, with expulsion of carbon monoxide. This method is analogous to the formation of carbenes formation from ketenes.
Ceric Ammonium Nitrate
Ceric ammonium nitrate (CAN) is the inorganic compound with the formula (NH4)2Ce(NO3)6. This orange-red, water-soluble salt is widely used as an oxidising agent in organic synthesis and as a standard oxidant in quantitative analysis.
The Barton Reaction involves the photolysis of a nitrite to form a δ-nitroso alcohol. It is named for the British chemist Sir Derek Harold Richard Barton.
mechanism of Barton reaction
The mechanism is believed to involve a homolytic RO−NO cleavage, followed by δ-hydrogen abstraction and free radical recombination.
The Hofmann-Löffler reaction or Hofmann-Löffler-Freytag Reaction is an organic reaction is which a haloamine is converted to a cyclic amine] such as a pyrrolidine with heat and an acid.
mechanism of Hofmann-Löffler reaction
The reaction type is a free radical reaction. In the key step a hydrogen atom migrates from a γ or δ carbon position to a nitrogen-centred radical in a rearrangement reaction. The distal radical is quenched by removing a chlorine atom from a second molecule of the chloroamine, regenerating the nitrogen radical and chain-carrying the reaction.
1,1'-Azobis(cyclohexanecarbonitrile) or ABCN is a radical initiator. The molecular formula is NCC6H10N=NC6H10CN. It is classified as highly flammable and an irritant.
Tributyltin hydride (Bu3SnH) is an organotin compound. It is a useful reagent in organic synthesis. Combined with azobisisobutyronitrile or by irradiation with light, tributyltin hydride cleaves to form the tributyltin radical (Bu3Sn•), which reacts with (an organic) substrate by substitution of a halogen atom for a hydrogen atom in a chain reaction.
The Prins reaction is an organic reaction consisting of an electrophilic addition of an aldehyde or ketone to an alkene or alkyne followed by capture of a nucleophile.
The outcome of the reaction depends on reaction conditions. With water and a protic acid such as sulfuric acid as the reaction medium and formaldehyde the reaction product is a 1,3-diol. When water is absent dehydration takes place to an allyl alcohol. With an excess of formaldehyde and a low reaction temperature the reaction product is a dioxane. When water is replaced by acetic acid the corresponding esters are formed.
mechanism of Prins reaction
The Barton-McCombie deoxygenation is an organic reaction in which an hydroxyl functional group in an organic compound is replaced by a hydride to give an alkyl group. R = alkyl and R' = H, Me, SMe (see also Chugaev elimination), OMe, Ph, OPh, Imidazolyl.
mechanism of Barton-McCombie deoxygenation
The alcohol is first converted to the thiocarbonyl derivative, and is then treated with tributyltin hydride (Bu3SnH) to do a radical substitution. Once the radical chain has been initiated, attack on the Bu3Sn• carrier by sulphur initiates a decomposition yielding the alkyl radical, for which Bu3SnH serves as hydrogen radical (H·) donor. The driving force for the reaction is the formation of the very stable S−Sn bonds.
Polymethylhydrosiloxane (PMHS) is a polymer with the general structure -(CH3(H)Si−O)-. It is used in organic chemistry as a mild and stable reducing agent easily transferring hydrides to metal centers.
Xanthate usually refers to a salt with the formula ROCS2‾M+ (R = alkyl; M+ = Na+, K+).
Xanthates also refer to esters of xanthic acid. These esters have the structure ROC(=S)SR'. They are versatile intermediates in organic synthesis.
formation of xanthate
Xanthate salts are produced by the reaction of an alcohol with sodium or potassium hydroxide and carbon disulfide:
* ROH + CS2 + KOH → ROCS2K + H2O
The reaction involves the attack of the alkoxide salt.
alkaylation of xanthate
Xanthate anions also undergo alkylation to give xanthate esters, which are generally stable:
ROCS2K + R'X → ROC(=S)SR' + KCl
The C−O bond in these compounds are suscetpible to cleavage by the Barton-McCombie deoxygenation, which provides a means for deoxygenation of alcohols.
Thiols are often referred to as mercaptans. The term mercaptan is derived from the Latin mercurium captans (capturing mercury) because the thiolate group bonds so strongly with mercury compounds.
In chemistry, a mesylate is any salt or ester of methanesulfonic acid (CH3SO3H). In salts, the mesylate is present as the CH3SO3‾ anion. When modifying the International Nonproprietary Name of a pharmaceutical substance containing the group or anion, the correct spelling is mesilate (as in imatinib mesilate, the mesylate salt of imatinib).
Mesylate esters are a group of organic compounds that share a common functional group with the general structure CH3SO2O−R , abbreviated MsO−R, where R is an organic substituent. Mesylate is considered an excellent leaving group in nucleophilic substitution reactions.
Mesyl is the term for the methanesulfonyl or CH3SO2- (Ms-) functional group. For example, methanesulfonyl chloride is often referred to as mesyl chloride.
preparation of mesylates
Mesylates may be prepared using an alcohol and methanesulfonyl chloride in the presence of a base, often amine bases such as triethylamine. Mesylates can also be prepared by combining an alcohol, methanesulfonic anhydride and base, although this method is generally used only if the nucleophilicity of chloride is a concern.
The Barton decarboxylation is a free radical reaction in which a carboxylic acid is first converted to a thiohydroxamate ester (commonly referred to as a Barton ester). The product is then heated in the presence of a radical initiator and a suitable hydrogen donor to complete the reductive decarboxylation of the initial carboxylic acid. Using this reaction it is possible to remove a carboxylic acid moiety from an alkyl group and replace it with other functional groups.
mechanism of Barton decarboxylation
The reaction is initiated by homolytic cleavage of a radical initiator, in this case 2,2'-azobisisobutyronitrile (AIBN), upon heating. A hydrogen is then abstracted from tributyltin hydride to leave a tri-n-butyltin radical that attacks the sulfur atom of the thiohydroxamate ester. The N−O bond of the thiohydroxamate ester is cloven to form a carboxyl radical which then undergoes decarboxylation and carbon dioxide (CO2) is lost. The remaining alkyl radical (R•) then abstracts a hydrogen atom from remaining tri-n-butyltin hydride to form the reduced alkane (RH).The tributyltin radical enters into another cycle of the reaction until all thiohydroxamate ester is consumed.
The reaction proceeds due to the formation of the stable S−Sn bond and aromatization of the thiohydroxamate ester. There is also an overall increase in entropy due to the formation of 3 products from 2 substrates which drives the reaction forward.
spontaneous N−O bond cleavage of the Barton ester
N−O bond cleavage of the Barton ester can also occur spontaneously upon heating or by irradiation with light to initiate the reaction.
radical recombination or substitution after spontaneous N−O bond cleavage of the Barton ester
If an excess of a suitable radical trapping agent is present in the reaction medium, substitution will occur; otherwise, radical recombination takes place to give the pyridyl sulfide:
In halolactonization, an alkene is attacked by a halogen via electrophilic addition with the cationic intermediate captured intramolecularly by an adjacent carboxylic acid (See also iodolactamization), for example in this iodolactonization:
generation of free radical from trialkylboron-oxygen
Triethylboron and 9-borabicyclo[3.3.1]nonane (9-BBN) are good radical sources for certain synthetic procedures. The reactions involve oxidation of the borane by oxygen.
R3B + O2 → R2B−O−O• + R•
These initiators can be used in conjunction with stannanes and halides, as well as other reagents that undergo facile chain reactions. The reaction can be initiated at temperatures as low as −78 °C.
silane as hydrogen atom donor
Si−H bond in silanes is relatively strong compared to the appropriate bond in tributyltin hydride. The discoveries gained from the 80's, that replacement of alkyl by silyl groups weakens the Si−H bond at the central silicon atom, were very important for the discovery of tris(trimethylsilyl)silane as reducing agent.1) (bond strengths: Bu3Sn−H 74 kcal/mol, Et3Si−H 90 kcal/mol, TMS3Si−H 79 kcal/mol).
The alcohol derivatives that have been successfully deoxygenated include thiocarbonates and xanthates. The trialkylboron-oxygen system for radical generation has been used with tris-(trimethylsilyl)silane or diphenylsilane as a hydrogen donor.
tris-(trimethylsilyl)silane as the hydrogen atom donor
Tris-(trimethylsilyl)silane as the hydrogen atom donor with AIBN as a radical initiator:
Alkenes with a hydroxyl group on both sides of the double bond are called enediols.
A reductone is a compound that has an enediol structure with an adjacent carbonyl-group.
Hexamethylphosphoramide, often abbreviated HMPA, is a phosphoramide (i.e. an amide of phosphoric acid) having the formula [(CH3)2N]3PO. This colorless liquid is a useful polar aprotic solvent and additive in organic synthesis.
Lithium bis(trimethylsilyl)amide (LiHMDS) is the organosilicon compound with the formula [(CH3)3Si]2NLi. This colourless solid is a strong non-nucleophilic base used for deprotonation reactions and as a ligand.
Lithium diisopropylamide is the chemical compound with the formula [(CH3)2CH]2NLi. Generally abbreviated LDA, it is a strong base used in organic chemistry for the deprotonation of weakly acidic compounds. The reagent has been widely accepted because it is soluble in non-polar organic solvents and it is non-pyrophoric. LDA is a non-nucleophilic base.
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