Reaction Of Cyclohexanone Research Articles

Trans-4-Hydroxy-l-proline Hydrazide-Trifluoroacetic Acid as Highly Stereoselective Organocatalyst for the Asymmetric Direct Aldol Reaction of Cyclohexanone

Protonated A,-benzyl-N '-L-prolyl-trans-4-hydroxy-L-proline hydrazide has been found to be superior to the L-proline hydrazide counterpart as the catalyst for the asymmetric aldol reaction of cyclohexanone and aromatic aldehydes, resulting in excellent diastereoselectivities (up to > 99:1 dr) and enantioselectivities (up to > 99% ee).

DBU catalyzed cyanoacylation of ketones with acyl cyanides

The reaction of cyclohexanone with benzoyl cyanide catalyzed by amines provides the corresponding O-benzoyl cyanohydrin adducts in moderate to good yields under mild conditions. Among the catalysts, DBU was found to be the most effective promoter allowing the reaction to proceed smoothly at room temperature and to give the corresponding O-acyl cyanohydrin adducts in higher yields for a variety of substituted cyclohexanones, cyclopentanone, acetone or pentan-3-one and various acyl cyanides.

A Highly Efficient Organocatalyst for Direct Aldol Reactions of Ketones with Aldedydes

L-proline amides derived from various chiral beta-amino alcohols that bear substituents with various electron natures at their stereogenic centers are prepared and evaluated for catalyzing the direct Aldol reaction of 4-nitrobenzaldehyde with acetone. Catalysts with strong electron-withdrawing groups are found to exhibit higher catalytic activity and enantioselectivity than their analogues with electron-donating groups. The presence of 2 mol % catalyst 4g significantly catalyzes the direct Aldol reactions of a wide range of aldehydes with acetone and butanone, to give the beta-hydroxy ketones with very high enantioselectivities ranging from 96% to >99% ee. High diastereoselectivity of 95/5 was observed for the anti Aldol product from the reaction of cyclohexanone, and excellent enantioselectivity of 93% ee was provided for anti Aldol product from the reaction of cyclopentanone.

Hydrogen transfer reaction of cyclohexanone with 2-propanol catalysed by CeO2-ZnO materials: Promoting effect of ceria

Ce-Zn-O mixed oxides were prepared by amorphous citrate process and decomposition of the corresponding acetate precursors. The resulting materials were characterised by TGA, XRD, UV-Vis-DRS, EPR, SEM and surface area measure- ments. XRD and DRS results indicated fine dispersion of the ceria component in the ZnO matrix. EPR results clearly indicate the presence of oxygen vacancy and defect centres in the composite oxide. Addition of CeO2 to ZnO produced mixed oxides of high surface area compared to the pure ZnO. Hydrogen transfer reaction was carried out on these catalytic materials to investigate the effect of rare earth oxide on the activity of ZnO. Addition of ceria into zinc oxide was found to increase the catalytic activity for hydrogen transfer reaction . The catalytic activity also depended on the method of preparation. Citrate process results in uniformly dispersed mixed oxide with higher catalytic activity.

Influence of the preparation method on the structural and surface properties of various magnesium oxides and their catalytic activity in the Meerwein–Ponndorf–Verley reaction

The Meerwein–Ponndorf–Verley (MPV) reaction of cyclohexanone with isopropyl alcohol, which yields cyclohexanol, was studied by using basic catalysts consisting of magnesium oxide. The oxides were prepared using various synthetic procedures including calcination of commercially available magnesium hydroxide and carbonate, calcination of magnesium hydroxides obtained from magnesium nitrate and sulphate, the sol–gel technique and precipitation by decomposition of urea. The solids thus obtained were characterized structurally by X-ray diffraction spectroscopy and their surface properties determined using gas adsorption measurements (of nitrogen for textural properties and carbon dioxide for basic properties). Based on the results, the most active catalyst was the solid prepared by rehydration and subsequent calcination of a magnesium oxide that was previously obtained from commercially available magnesium hydroxide.

Chiral auxiliaries as docking/protecting groups: biohydroxylation of selected ketones with Beauveria bassiana ATCC 7159

The concept of chiral docking/protecting groups for biohydroxylation was extended from cyclopentanone to other ketones. Reaction of cyclohexanone, ( R)-3-methylcyclohexanone, cycloheptanone, 5-methyl-2-hexanone and 4-methyl-2-pentanone with ( R)-2-amino-1-propanol and subsequent in situ benzoylation afforded the corresponding N-benzoylated oxazolidine derivatives. All substrates were hydroxylated with the fungus Beauveria bassiana ATCC 7159, one of which was diastereoselectively hydroxylated with a d.e. of 99%. In this manner, access to the corresponding hydroxylated ketones was provided.

Catalytic radical addition of ketones to alkenes by a metal–dioxygen redox system

Radical addition of ketones to alkenes catalyzed by Mn(OAc)2 combined with Co(OAc)2 using dioxygen as oxidant was developed; for instance, the reaction of cyclohexanone with oct-1-ene in the presence of very small amounts of Mn(OAc)2 and Co(OAc)2 under air (1 atm) gave 2-octylcyclohexanone in good selectivity; from styrene, a six-membered cyclic peroxide was isolated in good yield.

Reactions of 1-aryl-2,5-dimethylpyrroles with ketones

1-Aryl-2,5-dimethylpyrroles react with acyclic ketones with acid catalysis to give geminal di-2-pyrrolyl derivatives independently of the ratio of the reagents. The reaction of cyclohexanone and cycloheptanone occurs analogously with 2∶1 ratio of pyrrole to ketone. With an excess of cyclohexanone a cycloheptanone 1-aryl-2,5-dimethyl-3,4-dicyclohexenylpyrroles and substituted 4,5,6,7,8,9-hexahydro-2H-azulene[1,2-c]pyrrol-4-spirocycloheptane are produced respectively.

The adsorption and reaction of cyclohexanone on the Pt(111) surface

The interaction of cyclohexanone with the Pt(111) surface has been investigated by HREELS and TDS. At 160 K, the chemisorption of cyclohexanone induces a “red-shift” of the CO stretch band and a decrease in work function. Heating the sample from 220 to 370 K leads to complete disappearance of the dominant CH2 rocking band at 720 cm−1 and the CO stretching band at 1650 cm−1, indicating the dehydrogenation of the entire adlayer to form intermediate species. Strong bands of the dehydrogenated species appear at 860 and 3000 cm−1 which is different from phenoxy on Pt(111). Above ∼ 380K, the dehydrogenated species is decomposed to form hydrocarbon fragments and CO which directly desorbs into the vacuum.

A study of the organic by-products in the cyclohexanone ammoximation

The heterogeneous catalyzed ammoximation of cyclohexanone on titanium silicalite catalyst has been studied. Cyclohexanone oxime is formed by reaction of cyclohexanone with ammonia and hydrogen peroxide. The organic by-products formed in the reaction have been studied and the following products were identified: nitrocyclohexane, cyclohexenylcyclohexanone, cyclohexenone oxime and cyclohexanone azine. The effect of some reaction parameters on by-products formation have been investigated. Experiments have been performed to verify if these by-products are due to side or consecutive reactions and derive from non-catalyzed or catalyzed reactions.

Ammoximation reaction with titanium doped amorphous silica

The catalytic behavior and the role of the acidic sites and of the activated forms of molecular oxygen in the ammoximation reaction of cyclohexanone to cyclohexanone oxime were investigated on pure and titanium doped amorphous silicas. The samples were prepared by the sol-gel method under acidic and basic conditions. The introduction of low amounts of titanium on silicas, prepared under basic conditions, strongly increased the oxime yield and conversion. The sample containing 0.25% titanium resulted in a very active and selective catalyst. A further increase of the titanium content decreased the catalytic activity and also the catalyst deactivation, because of a decrease of the tars formation rate. The comparison of the catalytic data and the results of FT-IR and EPR analysis confirmed the bifunctional nature of the amorphous silica catalyst. On the first step of the reaction pathway, the imine formation, the paramount parameter is an intrinsic property of pure silica, related to its textural and structural features. The adsorption experiments showed that the silica prepared under basic conditions, the only active in ammoximation, was able to form surface imine on acidic sites. The nature and the role of the oxidizing sites seem more complex. EPR results showed the presence of radical species on titanium modified silica and also, in small amount, on silica itself; however, the oxime formation did not seem to be a property related only to the presence of activated oxygen species anchored to titanium sites. It has been proposed that the formation of oxime is due to a combined effect of the presence of tars and of the activated oxygen species due to the titanium, which are able to oxidize the imine to oxime.

Interpretation of the nature of oxidation sites of silica active in ammoximation reaction of cyclohexanone by surface potential measurements

The catalytic behaviour in the ammoximation reaction of cyclohexanone to cyclohexanone oxime and the presence of activated forms of molecular oxygen on different commercial silicas (Akzo F-7, Degussa A200, Cabosil) was investigated. The presence of O 2 − species in the same range of temperature at which the silicas are active in ammoximation reaction was detected. The investigated silicas presented different selectivities in cyclohexanone oxime but all of them gave a high amount of tars as by products in presence of molecular oxygen. It has been proposed that the O 2 − adsorbed on the surface of silica are only involved in the beginning a radical reaction responsible of the formation of tars and that the high activity in oxime formation presented by Akzo F-7 is mainly related to its mesoporosity and the presence of tars.

Synthesis and X-ray structural investigation of 6-chloro-10-phenyl-1,2,3,4-tetrahydroacridine

An X-ray structural study of 6-chloro-10-phenyl-1,2,3,4-tetrahydroacridine prepared by the reaction of cyclohexanone with 2-amino-5-chlorobenzofenone was carried out. At 20°Ca=24.215(6),b=8.967(2),c=15.006(3) A, β=115.57(2)°,V= 2939(1) A3,dcalc=1.310 g cm−3,Z=4, space groupC2/c, 1324 reflections, λMoKα,R=0.038. The cyclohexene ring has a half-chair conformation. The phenyl substituent is rotated 71.2° with respect to the plane of the quinoline fragment.

Stereoselectivities of nucleophilic additions to cyclohexanones substituted by polar groups. Experimental investigation of reductions of trans-decalones and theoretical studies of cyclohexanone reductions. The influence of remote electrostatic effects

A series of nine 4-substituted trans-decalones have been synthesized and submitted to hydride reduction by NaBH 4 . Equatorial electron-withdrawing substituents have very little effect on the stereoselectivity, while axial substituents have a large effect. Ab initio molecular orbital calculations on the reaction of cyclohexanone with lithium hybride gave a 1.8-kcal/mol preference for the axial transition state at the RHF/6-31G* level. Substituent effects were studied by calculations with substituents at the C 4 position in the transition structure

ChemInform Abstract: A New and Efficient Approach to Macrocyclic Keto Lactones.

AbstractTi‐catalyzed reaction of cyclohexanone (I) with the acetoxymethyl vinyl ketone (II) in the presence of methanol (III) and H2O2 yields methyl 10‐acetoxy‐9‐oxodecanoate (IV) which is subjected to hydrolysis, giving the hydroxy acid (V).

Synthesis of Dibasic Acids via Ketone Peroxides from Cycloalkanones

Preparation of dimethyl dodecanedioate in two steps was studied. The first step is the formation of methoxycyclohexyl peroxide by reaction of cyclohexanone with hydrogen peroxide and methanol in the presence of acid catalyst.The second is the dimerization of the resulting methoxycyclohexyl peroxide through the action of iron (II) sulfate to obtain the dimethyl dodecanedioate. In the first step, sulfonic acid in 0.01010.015 mol per mol of cyclohexanone is used as the catalyst. In the second step, the resulting methoxycyclohexyl peroxide can be used for the dimerization without purification. Various iron (II) salts, such as iron (II) sulfate, iron (II) ammoniumsulfate and ferrous chloride, are effective as the reducing reagents. The reaction can be conducted at a temperature below 10°C. Water should be used in excess in the redox reaction, if it is desired to obtain branched dibasic acid dimethyl esters. Cyclopentanone, cycloheptanone and 2-methylcyclohexanone gave the corresponding dibasic acid dimethyl esters, respectively.

ChemInform Abstract: Synthesis of Azo Benzo(b)thiophene Derivatives and Their Application as Disperse Dyes.

Abstract 2-Amino-4,5,6,7-tetrahydrobenzo[ b ]thiophene-3-carbonitrile and ethyl-2-amino-4,5,6,7-tetrahydrobenzo[ b ]thiophene-3-carboxylate were synthesised by reaction of cyclohexanone and sulphur with malononitrile and ethyl cyanoacetate respectively. These 2-aminothiophene derivatives were diazotised and coupled with a variety of coupling components to give azo dyes. The spectral properties of these dyes are reported. The dyes had generally good colouration and fastness properties on polyester.

Synthesis of azo benzo[b]thiophene derivatives and their application as disperse dyes

2-Amino-4,5,6,7-tetrahydrobenzo[ b]thiophene-3-carbonitrile and ethyl-2-amino-4,5,6,7-tetrahydrobenzo[ b]thiophene-3-carboxylate were synthesised by reaction of cyclohexanone and sulphur with malononitrile and ethyl cyanoacetate respectively. These 2-aminothiophene derivatives were diazotised and coupled with a variety of coupling components to give azo dyes. The spectral properties of these dyes are reported. The dyes had generally good colouration and fastness properties on polyester.

Mechanism of the Carboxylation of Cyclohexanone with Carbon Dioxide Catalyzed by 1,8-Diazabicyclo[5.4.0]undec-7-ene

Abstract The dependence of the rate of carboxylation upon the concentration of the reactant was investigated in dimethyl sulfoxide. The reaction rate depended upon the concentration of cyclohexanone and 1,8-diazabicyclo[5.4.0]undec-7-ene(DBU) in the first order, respectively. The reaction also followed first-order kinetics regarding the CO2 pressure in the range 50–400 Torr. From these reaction characteristics, it is suggested that carboxylation proceeds via a reaction between CO2 dissolved in dimethyl sulfoxide and the anion of cyclohexanone, rather than between the CO2 adduct with DBU and cyclohexanone. The results of carboxylation by the CO2 adduct with DBU and by CO2 dissolved in dimethyl sulfoxide also support the above conclusion. The formation of the cyclohexanone anion by a reaction of cyclohexanone with DBU was verified by the UV spectrum of a solution of concentrated DBU and cyclohexanone.

ChemInform Abstract: An Example of C‐Methylthiolation of an Enolate Anion by Dimethylsulfoxide.

AbstractThe reaction of cyclohexanone (I) with the system DMSO/KOH yields the known 2‐methylidenecyclohexanol (II) and the novel 2‐methylthiocyclohexanone (III), probably via the enolate of (I).