A simple method for the synthesis of substituted benzylic ketones: homologation of aldehydes via the in situ generation of aryldiazomethanes from aromatic aldehydes

A general method for the homologation of aldehydes to benzylic ketones has been developed. Aryldiazomethanes were generated in situ in the presence of an aldehyde by simply heating the tosylhydrazones of aromatic aldehydes in the presence of a stoichiometric amount of base in polar protic solvents. The resulting polar protic solvent promoted homologation afforded benzylic ketones in moderate to excellent yields with a variety of aldehydes. Isolation of the tosylhydrazones was not necessary; they could be prepared in ethanol and carried through the sequence without isolation. This methodology allows easy access to a wide variety of substituted aryldiazomethanes that would be difficult, or even impossible, to prepare via conventional methods and circumvents the toxicity and stability problems associated with the isolation and/or handling solutions of aryldiazomethanes.     

A simple and versatile method for the synthesis of acetals from aldehydes and ketones using bismuth triflate

Acetals are obtained in good yields by treatment of aldehydes and ketones with trialkyl orthoformate and the corresponding alcohol in the presence of 0.1 mol % Bi(OTf)3.4H2O. A simple procedure for the formation of acetals of diaryl ketones has also been developed. The conversion of carbonyl compounds to the corresponding 1,3-dioxolane using ethylene glycol is also catalyzed by Bi(OTf)3.4H2O (1 mol %). Two methods, both of which avoid the use of benzene, have been developed.     

A general method for the spectrophotometric determination of aromatic aldehydes

Analytical and Bioanalytical Chemistry - Aromatic aldehydes and some of their binary mixtures can be determined spectrophotometrically with diphenylamine in the presence of hydrochloric acid....     

A simple, user-friendly process for the homologation of aldehydes using tosylhydrazone salts

Aldehydes can be homologated to ketones in moderate to good yields using aryldiazomethanes generated in situ from tosylhydrazones. Chiral aldehydes can be employed with almost complete retention of configuration. The tosylhydrazones can also be generated in situ from the corresponding aldehyde leading to a one-pot process for coupling two different carbonyl compounds to give ketones.     

A general method for the spectrophotometric determination of aromatic aldehydes

Summary Aromatic aldehydes and some of their binary mixtures can be determined spectrophotometrically with diphenylamine in the presence of hydrochloric acid. Errors are in the range of 6–10%. Various other organic compounds do not interfere.

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Allgemeines Verfahren zur spektralphotometrischen Bestimmung aromatischer Aldehyde

Zusammenfassung Aromatische Aldehyde und einige ihrer binären Gemische können mit Diphenylamin in salzsaurer Lösung spektralphotometrisch bestimmt werden. Fehler sind im Bereich von 6–10%. Eine große Zahl anderer organischer Verbindungen stört nicht.

     

一种高效、洁净的还原醛的新方法

报道了在超临界CO2中，实现氢转移反应的新方法，这一方法以水为氢授体， 锌粉为电子授体，高选择性地还原对甲基苯甲醛为相应的醇，并初步研究了反应温 度、反应体系中CO2的压力、反应时间对还原反应的转化率的影响。     

A simple one-pot preparation of diazoacetoacetate derivatives from aldehydes

Diazoacetoacetate derivatives can be simply and efficiently prepared from aldehydes in a one-pot process involving initial DBU-promoted "aldol" condensation with ethyl diazoacetate followed by in situ oxidation with IBX. Aryl, alkyl, and unsaturated aldehydes are all viable substrates.     

A simple and efficient L-prolinamide-catalyzed alpha-selenenylation reaction of aldehydes

An efficient and simple l-prolinamide-catalyzed alpha-selenenylation reaction of aldehydes with N-(phenylseleno)phthalimide has been developed for the efficient preparation of alpha-phenylselenoaldehydes. Such compounds are versatile building blocks for the synthesis of alpha,beta-unsaturated aldehydes, allylic alcohols, and amines. [reaction: see text]     

A simple and convenient procedure for the synthesis of 1-aminophosphonates from aromatic aldehydes

A simple, efficient, possible industrial process has been developed for the synthesis of 1-aminophosphonic acids from simple starting materials. As described below, treatment of aromatic aldehydes with ammonia and reaction with diethyl phosphite gives diethyl N-(arylmethylene)-1-aminoaryl methylphosphonates, which can be easily hydrolyzed to diethyl 1-aminoarylmethylphosphonates. This method is easy, rapid, and good yielding for the synthesis of 1-aminoalkylphosphonates from simple starting materials.     

A simple and efficient method for solvent-free iodination of hydroxylated aromatic aldehydes and ketones using iodine and iodic acid by grinding method

<正>Green,mild and efficient iodination of hydroxylated aromatic aldehydes and ketones using iodine and iodic acid in the solidstate by grinding under solvent-free conditions at room temperature.This method provides several advantages such as environmentally friendly,short reaction times,high yields,non-hazardous and simple work-up procedure.     

A convenient method for the synthesis of α-Ketoesters from aldehydes

An efficient two step, two carbon homologation of aldehydes to α-ketoesters is described.     

A simple method for the purification of fluorine

A simple method for the purification of fluorine gas is described. With the exception of nitrogen and argon, all impurities usually present in commercial fluorine can be readily removed by 1) conversion of O₂ to non-volatile O⁺₂ salts, and 2) a 70 to 63°K trap-to-trap distillation.     

A simple method for a determination

The a term is a primary parameter that is used to indicate the deviation of the epithermal neutron distribution in the k ₀-standardization method of neutron activation analysis, k ₀-NAA. The calculation of a using a mathematical procedure is a challenge for some researchers. The calculation of a by the "bare-triple monitor" method is possible using the dedicated commercial software KAYZERO^®/SOLCOI^®. However, when this software is not available in the laboratory it is possible to carry out the calculation of a applying a simple iterative linear regression using any spreadsheets. This approach is described in this paper. The experimental data used in the example were obtained by the irradiation of a set of suitable monitors in the NAA #1 irradiation channel of the HANARO research reactor (KAERI, Korea). The results obtained by this iterative linear regression method agree well with the results calculated by the validated mathematical method.     

A simple spectrophotometric method for the microdetermination of methionine

Summary A simple spectrophotometric method for the determination of methionine is described. The method is based on the inhibitory activity of methionine on the reaction of lactic acid withp-hydroxydiphenyl. The method was developed with mixtures containing known amounts of lactic acid in concentrated sulphuric acid to which increasing amounts of methionine were added. The intensity of colour obtained decreased in proportion to the amount of methionine added (in the range 5–45g). The method is recommended for analysis of samples which contain methionine in the presence of different amino-acids.

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Zusammenfassung Ein einfaches spektrophotometrisches Verfahren zur Bestimmung von Methionin wurde beschrieben. Es beruht auf der hemmenden Wirkung des Methionins auf die Reaktion von Milchsäure mitp-Hydroxydiphenyl. Die Methode wurde mit Gemischen bekannter Milchsäuremengen in konz. Schwefelsäure ausgearbeitet, denen steigende Mengen Methionin zugesetzt wurden. Die Farbintensität nimmt proportional der Menge zugesetzten Methionins (5–45g) ab. Das Verfahren wurde zur Analyse von Proben empfohlen, die Methionin in Gegenwart verschiedener anderer Aminosäuren enthalten.

     

A simple method for the alkaline hydrolysis of esters

A very mild and rapid procedure for the efficient alkaline hydrolysis of esters in non-aqueous conditions has been developed, by the use of dichloromethane/methanol (9:1) as solvent. This method conveniently provides both carboxylic acids and alcohols from the corresponding esters and sodium hydroxide in a few minutes at room temperature. A plausible reaction mechanism is proposed.     

A simple method for the direct arylation of indoles

The scope and limitations are described for a powerful new method to access indoles bearing a quaternary center at C-3 using easily accessible bisaryl λ³-iodanes and a cheap organic base.     

A simple method for the preparation of pure hafnium

The separation of zirconium and hafnium by fractional precipitation as pyrophosphate¹ has been extended for the preparation of pure hafnium. The favourable uptake of hafnium, in spite of the decreasing tendency of partition factor when hafnium concentration is high, is maintained for all concentration of hafnium (relative to zirconium). Particularly significant is the fact that at very high concentrations of hafnium (at≈84%) the uptake of zirconium sharply falls. So pure hafnium can be prepared from natural zirconium by a simple process of eight or nine stages of fractional precipitations as pyrophosphate. This process yields reactor grade zirconium on the one side and pure hafnium on the other side.     

A simple spectrophotometric method for the determination of minoxidil

A simple and sensitive method for the determination of minoxidil using 3-methyl-2-benzothiazolinone hydrazone (MBTH) and Fe(III) as the coloring agent is described. The method is sensitive to permit the determination of 0.5–4.5 μg ml⁻¹ of minoxidil at 500 nm. The accuracy and precision of the method were checked by high-performance liquid chromatography.