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Gutmann, a chemist renowned for his work on non-aqueous solvents, described an acceptor-number scale for solvent Lewis acidity [4] with two reference points relating to the 31 P NMR chemical shift of Et 3 PO in the weakly Lewis acidic solvent hexane (δ = 41.0 ppm, AN 0) and in the strongly Lewis acidic solvent SbCl 5 (δ = 86.1 ppm, AN 100).
Substrates are broadly limited to methyl ketones and secondary alcohols oxidizable to methyl ketones, such as isopropanol.The only primary alcohol and aldehyde to undergo this reaction are ethanol and acetaldehyde, respectively. 1,3-Diketones such as acetylacetone also undergo this reaction. β-ketoacids such as acetoacetic acid will also give the test upon heating.
Branched alkanes are more thermodynamically stable than their linear (or less branched) isomers. For example, the highly branched 2,2,3,3-tetramethylbutane is about 1.9 kcal/mol more stable than its linear isomer, n-octane. [4]
The Seyferth–Gilbert homologation is a chemical reaction of an aryl ketone 1 (or aldehyde) with dimethyl (diazomethyl)phosphonate 2 and potassium tert-butoxide to give substituted alkynes 3. [ 1 ] [ 2 ] Dimethyl (diazomethyl)phosphonate 2 is often called the Seyferth–Gilbert reagent .
This first part of the process is a so-called A 3 coupling reaction (A 3 stands for aldehyde-alkyne-amine). In the second part, the α-amino alkyne then undergoes a formal retro-imino-ene reaction, an internal redox process, to deliver the desired allene and an imine as the oxidized byproduct of the secondary amine. [ 11 ]
Two approaches are taken. Traditionally the alkene is treated with sulfuric acid to give alkyl sulphate esters. In the case of ethanol production, this step can be written: H 2 SO 4 + C 2 H 4 → C 2 H 5-O-SO 3 H. Subsequently, this sulphate ester is hydrolyzed to regenerate sulphuric acid and release ethanol: C 2 H 5-O-SO 3 H + H 2 O → H 2 ...
Due to the activated nature of the cyclic carbon–carbon triple bond, many alkyne addition-type reactions such as the Diels–Alder, 1,3-dipolar cycloadditions and halogenation may be performed using very mild conditions and in the absence of the catalysts frequently required to accelerate the transformation in a non-cyclic system. In addition ...
In organic chemistry, hexene is a hydrocarbon with the chemical formula C 6 H 12.The prefix "hex" is derived from the fact that there are 6 carbon atoms in the molecule, while the "-ene" suffix denotes that there is an alkene present—two carbon atoms are connected via a double bond.