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Tris(2,2,2-trifluoroethyl) Borate
Tris(2,2,2-trifluoroethyl) borate, also commonly referred to as the Sheppard amidation reagent, is a chemical compound with the formula . This borate ester reagent is used in organic synthesis. Preparation Tris(2,2,2-trifluoroethyl) borate can be prepared by reaction of trifluoroethanol with boron trichloride, borane dimethylsulfide, boron tribromide, or boric anhydride. The latter is more convenient for larger scale preparations due to its low cost and ease of handling. : The product is purified by distillation. Applications The reagent is mostly used in condensation reactions. It has been shown to promote the direct formation of amides from carboxylic acids and amines as well as the formation of imines from amines or amides with carbonyl compounds. It has also been used for the coupling of unprotected amino acid Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although over 500 amino acids exist in nat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Borate Ester
In organic chemistry, borate esters are organoboron compounds which are conveniently prepared by the stoichiometric condensation reaction of boric acid with alcohols. There are two main classes of borate esters: orthoborates, and metaborates, . Metaborates contain 6-membered boroxine rings. :B(OH)3 + 3 ROH -> B(OR)3 + 3 H2O :3 B(OH)3 + 3 ROH -> B3O3(OR)3 + 6 H2O A dehydrating agent, such as concentrated sulfuric acid is typically added. Borate esters are volatile and can be purified by distillation. This procedure is used for analysis of trace amounts of borate and for analysis of boron in steel. Like all boron compounds, alkyl borates burn with a characteristic green flame. This property is used to determine the presence of boron in qualitative analysis. Borate esters form spontaneously when treated with diols such as sugars and the reaction with mannitol forms the basis of a titrimetric analytical method for boric acid. Metaborate esters show considerable Lewis acidity ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carbonyl
In organic chemistry, a carbonyl group is a functional group with the formula , composed of a carbon atom double bond, double-bonded to an oxygen atom, and it is divalent at the C atom. It is common to several classes of organic compounds (such as aldehydes, ketones and carboxylic acid), as part of many larger functional groups. A compound containing a carbonyl group is often referred to as a carbonyl compound. The term carbonyl can also refer to carbon monoxide as a ligand in an inorganic or organometallic complex (a metal carbonyl, e.g. nickel carbonyl). The remainder of this article concerns itself with the organic chemistry definition of carbonyl, such that carbon and oxygen share a double bond. Carbonyl compounds In organic chemistry, a carbonyl group characterizes the following types of compounds: Other organic carbonyls are urea and the carbamates, the derivatives of acyl chlorides, chloroformates and phosgene, carbonate esters, thioesters, lactones, lactams, Hydro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Borate Esters
In organic chemistry, borate esters are organoboron compounds which are conveniently prepared by the stoichiometric condensation reaction of boric acid with alcohols. There are two main classes of borate esters: orthoborates, and metaborates, . Metaborates contain 6-membered boroxine rings. :B(OH)3 + 3 ROH -> B(OR)3 + 3 H2O :3 B(OH)3 + 3 ROH -> B3O3(OR)3 + 6 H2O A dehydrating agent, such as concentrated sulfuric acid is typically added. Borate esters are volatile and can be purified by distillation. This procedure is used for analysis of trace amounts of borate and for analysis of boron in steel. Like all boron compounds, alkyl borates burn with a characteristic green flame. This property is used to determine the presence of boron in qualitative analysis. Borate esters form spontaneously when treated with diols such as sugars and the reaction with mannitol forms the basis of a titrimetric analytical method for boric acid. Metaborate esters show considerable Lewis acidity ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lewis Acid
A Lewis acid (named for the American physical chemist Gilbert N. Lewis) is a chemical species that contains an empty orbital which is capable of accepting an electron pair from a Lewis base to form a Lewis adduct. A Lewis base, then, is any species that has a filled orbital containing an electron pair which is not involved in bonding but may form a dative bond with a Lewis acid to form a Lewis adduct. For example, NH3 is a Lewis base, because it can donate its lone pair of electrons. Trimethylborane CH3)3Bis a Lewis acid as it is capable of accepting a lone pair. In a Lewis adduct, the Lewis acid and base share an electron pair furnished by the Lewis base, forming a dative bond. In the context of a specific chemical reaction between NH3 and Me3B, a lone pair from NH3 will form a dative bond with the empty orbital of Me3B to form an adduct NH3•BMe3. The terminology refers to the contributions of Gilbert N. Lewis. From p. 142: "We are inclined to think of substances as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dimethylformamide
Dimethylformamide, DMF is an organic compound with the chemical formula . Its structure is . Commonly abbreviated as DMF (although this initialism is sometimes used for 2,5-dimethylfuran, dimethylfuran, or dimethyl fumarate), this colourless liquid is Miscibility, miscible with Water (molecule), water and the majority of organic liquids. DMF is a common solvent for chemical reactions. Dimethylformamide is odorless, but chemical purity, technical-grade or degraded samples often have a fishy smell due to impurity of dimethylamine. Dimethylamine degradation impurities can be removed by Sparging (chemistry), sparging samples with an inert gas such as argon or by sonication, sonicating the samples under reduced pressure. As its name indicates, it is structurally related to formamide, having two methyl groups in the place of the two hydrogens. DMF is a polar molecule, polar (hydrophilic) aprotic solvent with a high boiling point. It facilitates reactions that follow polar mechanisms, such ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transamidation
Transamidation is a chemical reaction in which an amide reacts with an amine to generate a new amide: :RC(O)NR'2 + HNR"2 → RC(O)NR"2 + HNR'2 The reaction is typically very slow, but it can be accelerated with Lewis acid and organometallic catalysts. Primary amides (RC(O)NH2) are more amenable to this reaction. Ureas In contrast to the reluctance of amides as substrates, urea is more susceptible to this exchange process. Transamidation is practiced, sometimes even on an industrial scale, to prepare a variety of N-substituted ureas: :(H2N)2CO + R2NH → (R2N)(H2N)CO + NH3 :(R2N)(H2N)CO + R2NH → (R2N)2CO + NH3 Methylurea, precursor to theobromine, is produced from methylamine and urea. Phenylurea is produced similarly but from anilinium chloride:{{cite journal , title=Arylureas II. Urea Method p-Ethoxyphenylurea , journal=Org. Synth. , year=1951 , volume=31 , page=11 , doi=10.15227/orgsyn.031.0011 :(H2N)2CO + 6H5NH3l → (C6H5(H)N)(H2N)CO + NH4C ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Formylation
Formylation refers to any chemical processes in which a compound is functionalized with a formyl group (-CH=O). In organic chemistry, the term is most commonly used with regards to aromatic compounds (for example the conversion of benzene to benzaldehyde in the Gattermann–Koch reaction). In biochemistry the reaction is catalysed by enzymes such as formyltransferases. Formylation generally involves the use of formylation agents, reagents that give rise to the CHO group. Among the many formylation reagents, particularly important are formic acid and carbon monoxide. A formylation reaction in organic chemistry refers to organic reactions in which an organic compound is functionalized with a formyl group (-CH=O). The reaction is a route to aldehydes (''C''-CH=O), formamides (''N''-CH=O), and formate#Formate esters, formate esters (''O''-CH=O). Formylation agents A reagent that delivers the formyl group is called a formylating agent. * Formic acid * Dimethylformamide and phosphorus ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amino Acid
Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although over 500 amino acids exist in nature, by far the most important are the 22 α-amino acids incorporated into proteins. Only these 22 appear in the genetic code of life. Amino acids can be classified according to the locations of the core structural functional groups ( alpha- , beta- , gamma- amino acids, etc.); other categories relate to polarity, ionization, and side-chain group type ( aliphatic, acyclic, aromatic, polar, etc.). In the form of proteins, amino-acid '' residues'' form the second-largest component (water being the largest) of human muscles and other tissues. Beyond their role as residues in proteins, amino acids participate in a number of processes such as neurotransmitter transport and biosynthesis. It is thought that they played a key role in enabling life on Earth and its emergence. Amino acids are formally named by the IUPAC- IUBMB Joint Commi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coupling Reaction
In organic chemistry, a coupling reaction is a type of reaction in which two reactant molecules are bonded together. Such reactions often require the aid of a metal catalyst. In one important reaction type, a main group organometallic compound of the type R-M (where R = organic group, M = main group centre metal atom) reacts with an organic halide of the type R'-X with formation of a new carbon–carbon bond in the product R-R'. The most common type of coupling reaction is the cross coupling reaction. Richard F. Heck, Ei-ichi Negishi, and Akira Suzuki were awarded the 2010 Nobel Prize in Chemistry for developing palladium-catalyzed cross coupling reactions. Broadly speaking, two types of coupling reactions are recognized: *Homocouplings joining two identical partners. The product is symmetrical *Heterocouplings joining two different partners. These reactions are also called cross-coupling reaction In organic chemistry, a cross-coupling reaction is a reaction where tw ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Imine
In organic chemistry, an imine ( or ) is a functional group or organic compound containing a carbon–nitrogen double bond (). The nitrogen atom can be attached to a hydrogen or an organic group (R). The carbon atom has two additional single bonds. Imines are common in synthetic and naturally occurring compounds and they participate in many reactions. Distinction is sometimes made between aldimines and ketimines, derived from aldehydes and ketones, respectively. Structure In imines the five core atoms (C2C=NX, ketimine; and C(H)C=NX, aldimine; X = H or C) are coplanar. Planarity results from the sp2-hybridization of the mutually double-bonded carbon and the nitrogen atoms. The C=N distance is 1.29–1.31 Å for nonconjugated imines and 1.35 Å for conjugated imines. By contrast, C−N distances in amines and nitriles are 1.47 and 1.16 Å respectively. Rotation about the C=N bond is slow. Using NMR spectroscopy, both E–Z notation, ''E'' and ''Z'' isomers of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
