Aldehyde aliphatic

Ethanol [64-17-5] M 46.1, b 78.3 , d 0.79360, d 0.78506, n 1.36139, pK 15.93. Usual impurities of fermentation alcohol are fusel oils (mainly higher alcohols, especially pentanols), aldehydes, esters, ketones and water. With synthetic alcohol, likely impurities are water, aldehydes, aliphatic esters, acetone and diethyl ether. Traces of benzene are present in ethanol that has been dehydrated by azeotropic distillation with benzene. Anhydrous ethanol is very hygroscopic. Water (down to 0.05%) can be detected by formation of a voluminous ppte when aluminium ethoxide in benzene is added to a test portion. Rectified... 

Cinnamic Acid.—The reaction, which takes place when an aldehyde (aliphatic or aromatic) acts on the sodium salt of an aliphatic acid in presence of the anhychide, is known as Perkin s reaction, and has a ery wide application. Accoid-ing to the result of Fittig s researches on the properties of the unsaturated acids described below, the reaction occurs in two steps. The aldeh) de forms first an additive compound with the acid, the aldehyde caibon attaching itself to the n-carbon ii.e.i nevt the carbovyl) of the acid. A saturated hydiOKy-acid is formed, which is stable, if the a-carbon is attached to only one atom of hydrogen, as in the case of isobutync acid,... 

The Pictet-Spengler reaction has mainly been investigated as a potential source of polycyclic heterocycles for combinatorial apphcations or in natural product synthesis [149]. Tryptophan or differently substituted tryptamines are the preferred substrates in a cyclocondensation that involves also aldehydes or activated ketones in the presence of an acid catalyst. Several versions of microwave-assisted Pictet-Spengler reactions have been reported in the hter-ature. Microwave irradiation allowed the use of mild Lewis acid catalysts such as Sc(OTf)3 in the reaction of tryptophan methyl esters 234 with different substituted aldehydes (aliphatic or aromatic) [150]. Under these conditions the reaction was carried out in a one-pot process without initial formation of the imine (Scheme 86). 

Aldehydes and the corresponding 2-aminopyridine, pyrazine, or pyrimidine are admixed in presence of a catalytic amount of clay (50 mg) to generate iminium intermediate. Isocyanides are subsequently added to the same container and the reactants are further exposed to MW to afford the corresponding imidazo[l,2-a]pyridines, imi-dazo[l,2-a]pyrazines and imidazo[l,2-a]pyrimidines (Scheme 6.48). The process is general for all the three components, e. g. aldehydes (aliphatic, aromatic and vinylic), isocyanides (aliphatic, aromatic and cyclic) and amines (2-aminopyridine, 2-amino-pyrazine and 2-aminopyrimidine). A library of imidazo[l,2-a]pyridines, imidazo[l,2-ajpyrazines and imidazo[l,2-a]pyrimidines can be readily obtained by varying the three components [151]. 

Ex situ formation of (33) followed by addition to a mixture of CHCI3 and aldehyde (aliphatic or aromatic) in DMF at low temperature leads to deprotonation of CHCI3 but not of the aldehyde, and formation of the trichlorocarbinol takes place without formation of side products by aldol condensation, Scheme 21 [99]. The reaction could also be carried out (75-86% yield for butanal) using polymeric amides as a PB and with similar conditions [74]. 

C02Et Br KOf-Bu/THF/-20°C aliphatic and aromatic aldehydes aliphatic, cycloaliphatic and aromatic ketone, a,p-unsaturated aldehydes and ketones 52-90... 

Also in this case the acyl radical can be oxidized by the ferric salt, but in the presence of protonated heteroaromatic bases the aromatic attack successfully competes with the oxidation. The process has great versatility and can be carried out with a large variety of aldehydes (aliphatic, a,jS-unsaturated, aromatic, and heteroaromatic). 

Peaches and nectarines are members of the same species (Prunus persica). There is controversy over whether nectarine is a separate and distinct fruit or merely a variety of peach [68]. Nectarines lack skin fuzz or pubescence. Approximately 100 volatile compounds have been identified in peaches and nectarines, including alcohols, aldehydes, alkanes, esters, ketones, lactones and terpenes [14, 15, 17, 64, 65, 68-71]. Among them, lactones, particularly y-decalactone and d-decalactone, have been reported as character-impact compounds in peaches and nectarines where they process a strong peach-like aroma [66]. Lactones act in association with Ce aldehydes, aliphatic alcohols and terpenes (Table 7.2,... 

In contrast to aromatic aldehydes, aliphatic aldehydes invariably afforded complex mixtures of products when submitted to the above conditions. Based on their molecular weights, a few products could tentatively be identified as dialkylated, as well as dehydrodialkylated, compounds, such as 24. These perhaps were derived from tautomerization of the initially formed imine 19 to the thermodynamically more stable enamine 20 followed by reaction with a second aldehyde molecule and subsequent reduction (Scheme 3). 

Ene reaction of aldehydes. Aliphatic and aromatic aldehydes are not reactive enophiles however, in the presence of dimethylaluminum chloride, which serves as u mild Lewis acid catalyst and proton scavenger, ene reactions occur in reasonable to high yield. Use of C2HSA1C1 results in complex mixtures of products. This ene reaction is a useful route to homoallylic alcohols.2... 

Reaction with dimethylphenylsilane is catalyzed at room temperature under 250 psi of carbon monoxide. Other silanes tested, triethyl- and triphenylsi-lane, are not effective reagents in this system. A variety of aldehydes are good substrates for the reaction, including benzaldehyde, substituted benzaldehydes, and heterocyclic aldehydes. Aliphatic aldehydes also yield a-siloxy aldehyde products, but the reaction must be run at higher CO pressure (1000 psi) to avoid hydrosilylation. The reaction does not tolerate substrates bearing strong electron-withdrawing substituents, such as p-nitrobenzaldehyde. 

Similar polyacetals were prepared by BASF scientists from CO-aldehydic aliphatic carboxylic acids (189,190) and by the addition of poly(hydroxycarboxylic acid)s such as tartaric acid to divinyl ethers (191) as biodegradable detergent polymers. 

Lysine, 4-amino Aldehydes (aliphatic, aromatic, Reductive alkylation... 

The fermentation inhibitors include furan aldehydes, aliphatic acids, and phenolic compounds. The furan aldehydes, furfural, and hydroxymethyl furfural (HMF), are formed from pentoses and hexoses, respectively (4,5). Several studies indicate that furfural inhibits Saccharomyces cerevisiae, at least when present in high concentrations (6-10). HMF has a similar effect (11,12). 

Nickel-catalyzed transformations of SCBs have been studied by Oshima and co-workers <20060L483>. Nickel-catalyzed ring opening of SCBs with aldehydes affords the corresponding alkoxyallylsilanes (Scheme 55). This transformation represents a hydrosilane-free reductive silylation of aldehydes. A wide range of aldehydes (aliphatic, aromatic, electron-rich, and electron-deficient) can be converted to akoxyallylsilanes. 

The Hantzsch synthesis of dihydropyridines represents a classical example of MCR, generating an array of diversely substituted heterocycles in a one-pot reaction procedure. Given that the reaction requires elevated temperatures and extended reaction times to proceed, acceleration of the process by microwave irradiation could be envisioned. Indeed, dielectric heating of aldehyde (aliphatic or aromatic) and 5 equivalents of /i-keloesler in aqueous 25% NH4OH (used both as reagent and solvent) at 140-150 °C for merely 10-15 min furnished 4-aryl-l,4-dihydropyridines in 51-92% yield after purification on a silica gel column [100]. The Hantzsch synthesis under reflux conditions ( 100 °C) featured a remarkably longer time (12 hours) and lower yields (15- 72%). To demonstrate the suitability of the procedure for the needs of combinatorial chemistry, a 24-membered library of 1,4-dihydropyridines (DHP) was prepared (Scheme 36). 

Hexanol (aliphatic alcohol) ( )-2-Hexen-l-al (= tarc.y-2-Hexen-1 -al Leaf aldehyde) (aliphatic aldehyde)... 

Wittig-Horner reaction. The reagent reacts with a wide range of aldehydes, aliphatic, aromatic, and a,P-unsaturated, in the presence of a base to form (E)-a-methyl-a, -unsaturated esters stereoselectively. The reaction can be carried out either with potassium t-butoxide in DMF or with K,COj in QH /HjO and Aliquat 336 as phase-transfer agent. 

Pinanyl-9-BBN (Alpine borane 4) is a chiral borane that is readily oxidized by aldehydes. Aliphatic deuterioaldehydes undergo chiral reduction to give alcohols widi 84-98% The chiral alkene is regenerated in the process, only the hydrogen at the 2-position having been utilized, and can be reused. Equation (52) serves as an illustration of the stereochemistry of the process. 

A variety of aldehydes—aliphatic, aromatic, and heterocyclic—have been condensed with hydantoin. Sodium acetate in a mixture of acetic acid and acetic anhydride as well as pyridine containing traces of piperidine serves as condensing agent. Reduction of the double bond is accomplished with phosphorus and hydriodic acid, ammonium sulfide, or stannous chloride, In a more recent modification, the hydantoins are synthesized from aldehyde or ketone cyanohydrins and ammonium... 

Perfect chemoselectivity (100% of dithioacetals) was also achieved with kaolinitic clays as catalysts for protection of various aldehydes (aliphatic, aromatic, heteroaromatic, a,(I-unsaturated) with 1,2-ethanedithiol <1996TL4605>. 

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