Showing papers on "Benzaldehyde published in 1981"

Asymmetric cyanohydrin synthesis catalysed by a synthetic cyclic dipeptide

Abstract: Asymmetric addition of hydrogen cyanide to benzaldehyde catalysed by cyclo(L-phenylalanyl-L-histidine) gave the highest optical yield ever obtained.

Low Temperature Grignard Reactions with Pure Mg Slurries. Trapping of Cyclopropylmethyl and Benzocyclobutenylmethyl Grignard Reagents with CO2

Abstract: Cyclopropylmethyl bromide reacts readily at -75° with a Mg/THF slurry formed by evaporation of Mg in a rotating-solution reactor to yield after carbonation cyclopropyl acetic acid and 4-pentenoic acid in a ratio of 11:1. Addition of benzaldehyde to the Grignard solution again predominantly yields the addition product containing the cyclopropylmethyl unit. Using the same low temperature Grignard method, benzocyclobutenyl acetic acid is isolated upon carbonation of the Grignard reagent derived from the corresponding bromide, whereas under normal conditions o-vinylphenylacetic acid, the product corresponding to ring cleaved Grignard is obtained.

Kinetics and mechanism of reactions between aromatic olefins and hydroxyl radicals

Abstract: The rates of the reactions of hydroxyl radicals (OH) with styrene, α-methylstyrene, and β-methylstyrene have been measured by irradiating mixtures of these aromatic olefins and NO in an environmental chamber at 298 K. Experimental conditions were used whereby the competition of ozone with OH in oxidizing the hydrocarbons could be considered negligible. The rate constant values, obtained by a relative method using isooctane as reference hydrocarbon, are: styrene (5.3 ± 0.5) × 10−11 cm3/molec·s, α-methylstyrene (5.3 ± 0.6) × 10−11 cm3/molec·s, and β-methylstyrene (6.0 ± 0.6) × 10−11 cm3/molec·s. A simplified kinetic treatment of the experimental data shows that styrene and β-methylstyrene are stoichiometrically converted to benzaldehyde, suggesting that OH attack occurs only on the aliphatic moiety of the aromatic olefins. Benzaldehyde was observed to undergo consecutive oxidation by OH, and its maximum formation yield was about 60%. A reaction mechanism is proposed where the primary rate-determining OH attack leads to the formation of 1-hydroxy-2-phenyl-2-ethenyl radicals, from which benzaldehyde is formed through fast intermediate reactions.

Sodium borohydride reduction of adducts of primary amines with aldehydes and p-thiocresol. The alkylation of heterocyclic and aromatic amino-compounds

Abstract: p-Nitroaniline, 2-aminopyridine (1a), 4-aminopyridine (2a), 2-amino-4-methylpyrimidine (8a), 2-aminothiazole (10a), and 2-aminobenzimidazole (12a) react with aqueous formaldehyde and p-thiocresol in ethanol or methanol solution to give N-(p-tolythiomethyl) derivatives [corresponding to the general formula (4; R2= H)], usually in high yields. When the latter compounds are heated, under reflux, with an excess of sodium borohydride in ethanol or 1,2-dimethoxyethane solution, the corresponding methylamino-compounds [general formula (5; R2= H)] are obtained. By a similar two-step procedure in which aqueous formaldehyde is replaced, as appropriate, by anhydrous acetaldehyde, propionaldehyde, or benzaldehyde, p-nitroaniline is converted into N-ethyl-p-nitroaniline, p-chloroaniline is converted into p-chloro-N-(n-propyl)aniline, (1a) is converted into the corresponding ethylamino- and benzylamino-compounds (1c) and (1d), respectively, and (10a) and (12a) are converted into their 2-N-(n-propyl) derivatives (10c) and (12c), respectively.

Evaluation of models for the mechanism of action of 4-hydroxyphenylpyruvate dioxygenase

Abstract: 4-Hydroxyphenylpyruvic acid was oxygenated with various complexes of oxygen with Fe2+, superoxide ion, hydroperoxide anion, triplet and singlet oxygen. Oxidation occurred giving varying amounts of the 4-hydroxy derivatives of benzaldehyde, benzoic acid, phenol, phenylacetic acid and 4-carboxymethylquinone, but no homogentisic acid. 4-Hydroxyphenylperacetic acid was prepared and shown not to undergo self-oxidation. Its ferrous salt decomposed to 4-hydroxybenzyl alcohol. It is concluded that thea-keto carboxylic function is the site of oxygenation in the enzyme process and that a trioxalanone rather than a peracid intermediate may be implicated.

Hydroxyl derivatives of benzaldehyde for coloring keratin fibres in the absence of oxidizing agent

Abstract: The invention discloses the use of hydroxyl derivatives of benzaldehyde for coloring keratin fibres without an oxidizing agent. These derivatives are of the type which correspond to the formula: ##STR1## in which R denotes a linear or branched lower alkyl group which is optionally substituted by one or two OH groups, n is equal to 1, 2 or 3, m is equal to 0, 1 or 2 and the sum n+m is equal to 2 or 3.

Ammoniumsalze von α‐Ketocarbonsäuren eine Klasse neur Photoinitiatoren

Abstract: Ammoniumsalze von α-Ketocarbonsauren, z.B. Phenylglyoxylsaure oder Benzylidenbrenztraubensaure, spalten bei Belichtung in organischen Losungsmitteln unter Decarboxylierung in Aldehyde, z. B. Benzaldehyd oder Zimtaldehyd, und in das entsprechende ”freie“ Amin. Polyurethanlacke, die z.B. Ammoniumsalze der Phenylglyoxylsaure enthalten, harten nach Belichtung wesentlich schneller aus als unbelichtete Lacke. Ammoniumsalts of α-ketocarboxylic acids like phenylglyoxylic acid or benzylidenepyruvic acid are splitted under the influence of light into carbondioxide and aldehydes like benzaldehyde or cinnamic aldehyde and into the corresponding amine. This reaction is used for light-induced catalytic hardening of laquers based on polyurethanes.

Electro-organic reactions. Part 17. The competition between cleavage and ylid formation in the cathodic reduction of benzyl-, allyl-, cinnamyl-, and polyenyl-phosphonium salts

Abstract: In aprotic solvents benzyl-, allyl-, cinnamyl-, and polyenyl-phosphonium salts undergo overall one-electron reduction with the formation of up to 50% of the corresponding ylid. In cyclic voltammetric experiments peaks for the reduction of ylids have been clearly identified and the mechanism of formation is found to involve initial two-electron cleavage to a benzylic or allylic carbanion which abstracts proton from a second molecule of phosphonium salt. Benzyltriphenylphosphonium nitrate, in NN-dimethylformamide, is converted into the ylid by the dianion generated cathodically at –1.50 V versus saturated calomel electrode from dicyano(fluoren-9-ylidene)methane and in situ reaction with benzaldehyde gives stilbene in 74% yield. Competitive electrolyses in acidic solution of p-methoxycarbonylbenzyltriphenylphosphonium and triethylammonium salts, and p-methoxycarbonylbenzyl naphthalene-1-carboxylate give for these two-electron cleavages a qualitative order of leaving group ability of Et3N > Ph3P RCO2–.

The total synthesis of some deuterium labelled pentaketide derivatives of orsellinic acid

Abstract: The total syntheses of 4,6-dihydroxy-3,5-dimethyl-2-(1-methyl-2-oxopropyl)benzaldehyde and 6,8-dihydroxy-3,4,5,7-tetramethyl-3,4-dihydroisocoumarin, which allow the insertion of specific deuterium labels, are described.

A single crystal EPR study of the 3ππ* benzaldehyde in benzoic acid host

Abstract: We have made a single crystal EPR study of the 3ππ* benzaldehyde (BA) in benzoic acid (BAC) host. It was shown that there are two different sites for BA in BAC host. The orientations of BA in these sites were determined from the analysis of the hyperfine structure (hfs). The detailed analysis of the hfs shows the following spin distributions. Site 1: ρ2=0.09, ρ4=0.33, ρ6=0.12, and ρ7≲0.03; and Site 2: ρ2 =0.09, ρ4=0.33, ρ6=0.09, and ρ7=0.06. Here positions 2 and 6 are ortho and 4 is para to the formyl group. Carbon 7 is the formyl carbon. A very small value of ρ7 is a striking difference to a very large ρ7 in the BA anion. We have made a UHF calculation of the spin densities. The results of the UHF calculation are in good agreements with the experimental results. It is shown that the spin distribution in the π* orbital in the 3ππ* benzaldehyde is very different from that in the 3nπ* state obtained from an INDO calculation.

Reaction of Organic Tin(II) Compound with Carbonyl Compound

Abstract: The reactions of organic tin(II) compounds bearing Sn–OC bonds with carbonyl compounds, C6H5COR (R=C6H5CO, C6H5, and H) and p-benzoquinone, have been investigated. The tin(II) compound reacted with benzil and p-benzoquinone to yield the corresponding oxidative addition products. However, the oxidative addition reaction did not occur in benzophenone and benzaldehyde.

Process for conversion of toluene to benzaldehyde

Abstract: Benzaldehyde is prepared by the oxidation of toluene in the presence of a catalyst composed of the oxides of copper, iron, uranium, lead, tellurium, molybdenum, and phosphorous which can also include some other promoter elements.

Application of the combination of sodium bisulfite as a protective reagent and solid supports in the selective reduction of 4-acetylbenzaldehyde with diborane

Abstract: 4-Acetylbenzaldehyde (2) has been selectively reduced by using a combination of protective group and solid supports. The formyl group of 2 was protected by addition of sodium bisulfite. The adduct, supported on silica gel, was then selectively reduced to 4-(1-hydroxyethyl)benzaldehyde with diborane.

Catalysis of metal(II) acetate-2,2'-bipyridine complexes in the aldol condensations.

Abstract: The rate of the condensation of benzaldehyde with excess acetophenone catalyzed by Co(II) acetate-2,2′-bipyridine complex was obtained by GLC analysis. The rate increased in proportion as the amount of the complex catalyst. 2,2′-Bipyridine ligand in the Co(II) complex enhanced the catalytic activity remarkably, though the ligand itself had no activity. When the molar ratio of Co(II): bpy was 1 : 1 or 1 : 2, the highest activity was observed. The activation energy of the complex (1 : 1) catalyzed reaction was calculated as 13.7 kcal/mol. The catalysis of the complex behaved like a base catalyst. Briefly, the relation of the complex catalyzed aldol condensations with the enzymatic reaction of Class II aldolase is also described.

Catalytic effects of transition metal ions on photoinitiated oxidation of benzaldehyde by molecular oxygen

Abstract: Photoinitiated oxidation of benzaldehyde by molecular oxygen is catalyzed by transition metal ions. The classical free radical chain mechanism does not furnish explanation of this fact.

Purification of bis(alkylbenzylidene)sorbitol

Abstract: PURPOSE: To purify the titled compound useful as an additive for resins industrially advantageously, by heat-treating a crude reaction product of sorbitol and a benzaldehyde in a specific pH in the presence of an organic solvent so that unreacted substances and by-product are eliminated. CONSTITUTION: Sorbitol is dehydrated and condensed with benzaldehyde or an alkylbenzaldehyde in the presence of an acid catalyst to give a reaction product, which is heat-treated in a pH of ≥7 in the presence of a lower aliphatic ketone (e.g., acetone, methyl ethyl ketone, etc.), so that a compound shown by the formulaI(R is H or 1W3C alkyl; n is 1W3) is separated and purified. An alkali for making the pH ≥7 is NaOH, Na 2 CO 3 , KOH, etc. A by-product shown by the formula II is eliminated effectively by the purification, and unreacted sorbitol, benzaldehyde, etc. are also removed. The compound shown by the formulaI, having high purity as an additive for polyolefin resins useful as parts for foods or medical device, is obtained. COPYRIGHT: (C)1982,JPO&Japio

Process for synthesizing estrone or estrone derivatives

Abstract: What are disclosed are a multi-step synthesis for the preparation of 9(11)-dehydroestrone 3-methyl ether from 2-methyl,4-methoxy benzaldehyde; 1-(4-methoxy-2-methyl-(phenyl)-3-(1-methyl-2-oxo-5-t-vinyl-cyclopent-r-yl)-propane-1-one, an intermediate in said synthesis; and a method for the preparation of 3-vinylcyclopentanone from 2-vinylcyclopropane-1,1-dicarboxylic acid.

Autorecycling system for reduction of carbonyl compounds to alcohols by 1,5-dihydro-5-deazaflavins

Abstract: An effective recycling system for the reduction of carbonyl compounds to alcohols was constructed for the first time using 5-deazaflavins and formic acid, in such a way that each mol of the compound catalyses the reduction, by formic acid, of up to 25 mol of benzaldehyde.

Substituted biphenyl-2-carboxaldehydes and a process for preparing them

Abstract: Substituted biphenyl-2-carboxaldehydes are prepared in good yield by reacting palladium complexes of substituted benzaldehyde aniline Schiff bases with substituted phenylmagnesium bromides in the presence of at least six, preferably eight, molar equivalents of triphenylphosphine. Those compounds are intermediates for synthetic, in vivo cholesterol synthesis inhibitors.

The formation of the anion from 1-Thiacyclohept-2-ene 1-Oxide and its reaction with substituted benzaldehydes

Abstract: On treatment with bases 1-thiacyclohept-2-ene 1-oxide affords the 2-metallated derivative which rapidly polymerizes, except in the presence of tetramethylethylenediamine when the pale yellow anion is relatively stable in tetrahydrofuran solution at - 78o. The anion reacts rapidly with methyl iodide and with benzaldehyde and gives 2-methyl-1-thiacyclohept-2-ene 1-oxide and 2-(1-hydroxy- 1-phenylmethy1)-1-thiacyclohept-2-ene 1-oxide respectively in high yields. Substituted benzaldehydes react similarly to benzaldehyde and whilst the ratio of diastereomeric products formed is affected by the nature of the substituent, no clear correlation emerges. The reactions are subject to kinetic control and it is proposed that an unfavourable lone-pair, π-cloud electronic interaction is responsible for the diastereoselection.

Corrosion inhibitor comprising the ethynylation reaction product of a dialkylamine, a substituted benzaldehyde and acetylene

Abstract: A corrosion inhibitor for aqueous solutions of mineral acids consisting essentially of the reaction product obtained by the catalytic ethynylation of a dialkylamine, a substituted benzaldehyde and acetylene, said reaction product being a complex material which contains predominately a 3-dialkylamino-3-(substituted phenyl) prop-l-yne.