- A novel application of terminal alkynes as the homogeneous catalysts for acetalization and esterification
-
The theoretical study focused on the possible use of low-molecular-weight mono-as well as multifunctional terminal alkynes as catalysts for two reactions, which are known to be typically acid catalyzed - acetalization and esterification, is presented in this study. Multifunctional terminal alkynes [(diethynylbenzenes, triethynylbenzene, and tetrakis(4-ethynylphenyl)methane]were significantly more active than the monofunctional ones (cyclopropylacetylene, phenylacetylene, 3-cyclohexylprop-1-yne, 1-ethynyl-2-fluorobenzene, 1-ethynyl-4-fluorobenzene, 4-ethynyltoluene, 4-tert-butylphenylacetylene, and 2-ethynyl-α,α,α-trifluorotoluene), this fact can be partly explained by the higher amount of ethynyl groups per alkyne molecule. We confirmed that terminal ethynyl groups in low-molecular-weight alkynes can successfully act as acid catalytic centers for acetalization as well as for esterification.
- Sekerová, Lada,Vysko?ilová, Eli?ka,?erveny, Libor,Sedlá?ek, Jan
-
-
Read Online
- Hyper-Cross-Linked Polyacetylene-Type Microporous Networks Decorated with Terminal Ethynyl Groups as Heterogeneous Acid Catalysts for Acetalization and Esterification Reactions
-
Heterogeneous catalysts based on materials with permanent porosity are of great interest owing to their high specific surface area, easy separation, recovery, and recycling ability. Additionally, porous polymer catalysts (PPCs) allow us to tune catalytic activity by introducing various functional centres. This study reports the preparation of PPCs with a permanent micro/mesoporous texture and a specific surface area SBET of up to 1000 m2 g?1 active in acid-catalyzed reactions, namely aldehyde and ketone acetalization and carboxylic acid esterification. These PPC-type conjugated hyper-cross-linked polyarylacetylene networks were prepared by chain-growth homopolymerization of 1,4-diethynylbenzene, 1,3,5-triethynylbenzene and tetrakis(4-ethynylphenyl)methane. However, only some ethynyl groups of the monomers (from 58 to 80 %) were polymerized into the polyacetylene network segments while the other ethynyl groups remained unreacted. Depending on the number of ethynyl groups per monomer molecule and the covalent structure of the monomer, PPCs were decorated with unreacted ethynyl groups from 3.2 to 6.7 mmol g?1. The hydrogen atoms of the unreacted ethynyl groups served as acid catalytic centres of the aforementioned organic reactions. To the best of our knowledge, this is first study describing the high activity of hydrogen atoms of ethynyl groups in acid-catalyzed reactions.
- Sekerová, Lada,Lhotka, Miloslav,Vysko?ilová, Eli?ka,Faukner, Tomá?,Slováková, Eva,Brus, Ji?í,?erveny, Libor,Sedlá?ek, Jan
-
-
Read Online
- Low pressure hydroformylation in the presence of alcohol promoters
-
Active carbon supported cobalt catalyst was studied for the hydroformylation of 1-hexene in the presence of alcohol solvents at low pressure. The influence of various solvents on the hydroformylation and the CO conversion vs time on stream were investigated in detail. It was found that the heterogeneous catalyst shows excellent activity only in the alcohol solvents.
- Li, Baitao,Li, Xiaohong,Asami, Kenji,Fujimoto, Kaoru
-
-
Read Online
- AN EFFICIENT SbCl3-METAL SYSTEM FOR ALLYLATION, REDUCTION AND ACETALIZATION OF ALDEHYDES
-
SbCl3-Fe or SbCl3-Al could induce allylation of aldehydes with allylic halides at room temperature to give high yields of the corresponding homoallylic alcohols with high regio- and chemoselectivity.SbCl3-Al or SbCl3-Zn in DMF-H2O was found to be an efficient reduction system for conversion of aldehydes to alcohols at room temperature in excellent yields.While alcohol was used as solvent instead of DMF-H2O, the acetalization product was obtained in almost quantitative yield.Catalytic amount of SbCl3 was effective for this purpose.This acetalization method could also be applied to ketone.
- Wang, Wei-Bo,Shi, Li-Lan,Huang, Yao-Zeng
-
-
Read Online
- A simple one-pot procedure for the conversion of aldehydes to methyl esters
-
Several methyl esters were obtained by an efficient and simple one-pot procedure from the corresponding aldehydes in high yields. This procedure involves dimethyl acetal formation from aldehydes and subsequent oxidation.
- Rhee, Hakjune,Kim, Jin Yeon
-
-
Read Online
- 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.
- Leonard, Nicholas M.,Oswald, Matthew C.,Freiberg, Derek A.,Nattier, Bryce A.,Smith, Russell C.,Mohan, Ram S.
-
-
Read Online
- A convenient and highly efficient method for the protection of aldehydes using very low loading hydrous ruthenium(III) trichloride as catalyst
-
A convenient method for the chemoselective protections of both aliphatic and aromatic aldehydes has been developed. Ruthenium(III) trichloride (0.1 mol %) has found to be an highly efficient catalyst in the acetalizations of aldehydes with various simple alcohols such as methanol, ethanol, or diols such as 1,2-ethylanediol and 1,3-propanediol under mild reaction conditions.
- Qi, Jian-Ying,Ji, Jian-Xin,Yueng, Chi-Hung,Kwong, Hoi-Lun,Chan, Albert S.C.
-
-
Read Online
- Use of delaminated zeolites (ITQ-2) and mesoporous molecular sieves in the production of fine chemicals: Preparation of dimethylacetals and tetrahydropyranylation of alcohols and phenols
-
The combination of zeolitic acidities, easy reactant accessibility, and fast desorption-diffusion of products are determinant issues for designing successful catalysts for acid-catalyzed reactions in the field of fine chemicals production. Protection of aldehydes by formation of the corresponding dimethyl acetals and of alcohols and phenols by formation of the corresponding tetrahydropyranyl ethers were performed using ITQ-2 zeolite as acid catalyst. Its catalytic activity for these reactions was compared with those obtained with MCM-22, Beta zeolites, and the mesoporous aluminosilicate MCM-41, all with similar Si/Al ratios. When the reactions involved bulky reactants, ITQ-2 showed, in all cases, the highest activity as a consequence of the combination of its delaminated structure and the presence of strong acid sites. The zeolitic nature of the acid sites present in the delaminated ITQ-2 zeolite made the acid sites more stable than those present in the short range amorphous MCM-41 molecular sieve, providing the former catalyst better activity and thermal regenerability. ITQ-2 and MCM-41 are active and selective catalysts for acetalization reactions involving reactants as large as diphenylacetaldehyde and cholesterol.
- Corma,Rodriguez,Climent,Iborra,Fornes
-
-
Read Online
- Metal organic frameworks as solid acid catalysts for acetalization of aldehydes with methanol
-
Room temperature acetalization of aldehydes with methanol has been carried out using metal organic frameworks (MOFs) as solid heterogeneous catalysts. Of the MOFs tested, a copper-containing MOF [Cu3(BTC)2] (BTC=1,3,5-benzenetricarboxylate) showed better catalytic activity than an iron-containing MOF [Fe(BTC)] and an aluminium containing MOF [Al 2(BDC)3] (BDC=1,4-benzenedicarboxylate). The protocol was validated for a series of aromatic and aliphatic aldehydes and used to protect various aldehydes into commercially important acetals in good yields without the need of water removal. In addition, the reusability and heterogeneity of this catalytic system was demonstrated. The structural stability of MOF was further studied by characterization with powder X-ray diffraction, Brunauer-Emmett- Teller surface area measurements and Fourier-transformed infrared spectroscopic analysis of a deactivated catalyst used to convert a large amount of benzaldehyde. The performance of copper MOF as acetalization catalyst compares favourably with those of other conventional homogeneous and heterogeneous catalysts such as zinc chloride, zeolite and clay. Copyright
- Dhakshinamoorthy, Amarajothi,Alvaro, Mercedes,Garcia, Hermenegildo
-
-
Read Online
- Chemoselective protection of aldehydes in the presence of ketones using rupvp complex as a heterogeneous catalyst
-
Ruthenium(III)-polyvinyl pyridine (RuPVP) complex was prepared by refluxing a methanolic solution of polyvinyl pyridine and trihydrated ruthenium trichloride. RuPVP catalyst was characterized by Fourier transform-infrared and diffential scanning calorimetry-thermogravimetry (TG). The catalyst was used for chemoselective protection of aldehydes in the presence of a ketonic carbonyl group.
- Kshirsagar, Siddheshwar W.,Patil, Nitin R.,Samant, Shriniwas D.
-
-
Read Online
- Photochemical Hydroformylation of Olefins in the Cobalt-Phosphine Catalyst System
-
Cobalt-catalyzed hydroformylation of olefins was found to proceed even at ambient temperature under UV irradiation in the presence of phosphine.Extremely high selectivity toward straight-chain aldehyde (99percent in case of 1-hexene) was obtained by lower
- Mori, Sadayuki,Tatsumi, Shunji,Yasuda, Masaki,Kudo, Kiyoshi,Sugita, Nobuyuki
-
-
Read Online
- Practical acetalization and transacetalization of carbonyl compounds catalyzed by recyclable PVP-I
-
A novel PVP-I catalyzed acetalizations/transacetalizations of carbonyl compounds has been developed processing with a mild and easy handling fashion. Different types of Acyclic and cyclic acetals were prepared from carbonyl compounds or their acetals successfully. Further applications of newly developed catalytic combination were testified. This protocol featured with simplicity of operation, mild reaction condition, short reaction time, recyclable of catalyst and broad substrates scope with excellent yields.
- Cao, Fu-Rong,Lu, Guangying,Ren, Jiangmeng,Wang, Di,Zeng, Bu-Bing
-
-
- Two-way homologation of aliphatic aldehydes: Both one-carbon shortening and lengthening via the same intermediate
-
Aliphatic aldehydes can be homologated to both one-carbon shorter and one-carbon longer homologous carbonyl compounds through the 2–4 steps of reactions via the same intermediates, β,γ-unsaturated α-nitrosulfones, prepared from the proline-catalyzed sequential reactions of several aliphatic aldehydes with phenylsulfonylnitromethane. While the oxidative cleavage of the key intermediates gave one-carbon less homologous carbonyl compounds, the reduction of the same key intermediates followed by an oxidation produced one-carbon more homologous carbonyl compounds.
- Yoo, Jae Won,Seo, Youngran,Park, Jong Beom,Kim, Young Gyu
-
-
- Phosphine-ligated Ir(III)-complex as a bi-functional catalyst for one-pot tandem hydroformylation-acetalization
-
The complexation of IrCl3?3H2O with the electron-deficient phosphines (L1-L6) respectively afforded a bi-functional catalyst possessing the dual functions of transition metal complex (IrIII-P) and IrIII-Lewis acid for tandem hydroformylation-acetalization of olefins. The best result was obtained over L5-based IrCl3?3H2O catalytic system which corresponded to 97% conversion of 1-hexene along with 92% selectivity to the target acetals free of any additive. The crystal structure of the novel IrIII-complex of IrIII-L4 indicated that the electron-deficient nature of the involved phosphine warranted Ir-center in +3 valence state without reduction, which served as the Lewis acid catalyst for the subsequent acetalization of the aldehydes as well. Moreover, as an ionic phosphine, L6-based IrCl3?3H2O system immobilized in RTIL of [Bmim]PF6 could be recycled for 6 runs without the obvious activity loss or metal leaching.
- Liu, Huan,Liu, Lei,Guo, Wen-Di,Lu, Yong,Zhao, Xiao-Li,Liu, Ye
-
p. 215 - 221
(2019/04/17)
-
- Formation of Acetals and Ketals from Carbonyl Compounds: A New and Highly Efficient Method Inspired by Cationic Palladium
-
The development of a new, highly efficient, and simple method for masking carbonyl groups as acetals and ketals is described. This methodology relies on the nature of the palladium catalyst to direct the acetalization/ketalization reaction. This new protocol is mild and proceed with a very low catalyst loading at ambient temperatures. The method has been extended to a wide variety of different carbonyl compounds with various steric encumbrances to form the corresponding acetals and ketals in excellent yields.
- Green, Shawn D.,Kindoll, Tyler,Lazaro-Martinez, Brenda,Mensah, Enoch A.,West, Jesse
-
p. 1810 - 1814
(2019/09/09)
-
- Nickel-Catalyzed Chemoselective Acetalization of Aldehydes With Alcohols under Neutral Conditions
-
A molecularly defined NiII-complex catalyzing the chemoselective acetalization of aldehydes with alcohols under neutral conditions is reported. The reaction is general, efficient and showed a wide substrate scope (including aliphatic aldehydes) as well as excellent functional group tolerance. Reusability of the present nickel catalyst is also demonstrated.
- Subaramanian, Murugan,Landge, Vinod G.,Mondal, Akash,Gupta, Virendrakumar,Balaraman, Ekambaram
-
supporting information
p. 4557 - 4562
(2019/08/30)
-
- House bulb light-induced photochemical acetalization of carbonyl compounds catalyzed by Eosin Y
-
We have systematically studied the reactions of acetalization and found that high reaction efficiency can be achieved using cheap and readily available organic Eosin Y as catalyst. The reaction proceeds smoothly under house bulbs and shows excellent functional group tolerance. The substrates of the reaction system are compatible with aromatic aldehydes, aliphatic aldehydes, aromatic ketones, and cyclic ketones with high yields.
- Zhou, Quan,Jia, Tao,Li, Xiao-Xuan,Zhou, Lin,Li, Chang-Jiang,Feng, Yi-Si
-
supporting information
p. 1068 - 1075
(2018/05/23)
-
- Selective hydroformylation-acetalization of various olefins using simple and efficient Rh-phosphinite complex catalyst
-
A simple and efficient Rh-phosphinite complex catalyst was studied for the selective hydroformylation of various olefins. The influence of various reaction parameters including the effect of temperature, pressure, catalyst loading, time, and solvents was studied. The protocol was also applied for the synthesis of various acetals via tandem hydroformylation-acetalization of olefins in alcohols as solvents. High activity and selectivity for acetal formation was achieved in the absence of co-catalysts with admirable substrate to catalyst mole ratio (TON 2500). The developed protocol works for a wide range of olefins to synthesize corresponding aldehydes and acetals under optimized reaction conditions.
- Khan, Shoeb R.,Bhanage, Bhalchandra M.
-
p. 5998 - 6001
(2013/10/22)
-
- A recyclable fluorous hydrazine-1,2-bis(carbothioate) with NCS as efficient catalysts for acetalization of aldehydes
-
A fluorous hydrazine-carbothioate organocatalyst was prepared. Together with NCS, the catalyst showed a good activity in acetalization of aldehydes and alcohols. It could be recovered from the reaction mixture by fluorous solid-phase extraction (F-SPE) with excellent purity for direct reuse.
- Zhu, Yi-Wei,Yi, Wen-Bin,Cai, Chun
-
supporting information
p. 890 - 892
(2013/07/05)
-
- Efficient and chemoselective acetalization and thioacetalization of carbonyls and subsequent deprotection using InF3 as a reusable catalyst
-
An efficient and chemoselective method for preparation of acetals and dithioacetals of aldehydes and their deprotection under catalysis of InF 3 is described.
- Madabhushi, Sridhar,Mallu, Kishore Kumar Reddy,Chinthala, Narsaiah,Beeram, China Ramanaiah,Vangipuram, Venkata Sairam
-
experimental part
p. 697 - 701
(2012/02/15)
-
- Mesoporous sulfated zirconia mediated acetalization reactions
-
A novel, convenient, one step synthetic procedure for the synthesis of mesoporous sulfated zirconia (m-SZ) using zirconium carbonate complex and its use as solid acid catalyst for the acetalization of different carbonyl compound is reported. The high specific BET surface area (234 m2 g -1) of m-SZ is achieved after the removal of the surfactant (cetyltrymethylammonium bromide, CTAB) through calcination at 550 °C for 6 h. Microscopic analysis indicated the presence of spherical particles with worm like pores. DRIFT (diffuse reflectance FTIR) of pyridine adsorbed m-SZ and NH3-TPD (temperature programmed desorption) analysis suggested the presence of appreciable amount of Bro?nsted acid sites. The synthesized m-SZ showed high catalytic activity towards protection of carbonyl compounds through acetal/ketal formation. For the open ketal (from cyclohexanone and methanol) 97% conversion with 100% selectivity was obtained in 1 h at room temperature under solvent free condition. The catalyst can be easily recycled after separation from the reaction system without considerable loss in catalytic activity.
- Sinhamahapatra, Apurba,Sutradhar, Narottom,Ghosh, Malay,Bajaj, Hari C.,Panda, Asit B.
-
experimental part
p. 87 - 93
(2012/04/10)
-
- Acetalization of heptanal over Al-SBA-1 molecular sieve
-
Al-SBA-1 (Si/Al = 40, 80 and 120) and Al,Mg-SBA-1 (Si/(Al + Mg) = 40 and 80) molecular sieves were synthesized and characterized. Acetalization of n-heptanal with methanol was studied under autogenous pressure between 80 and 150 °C. Since protonation of n
- Venkatachalam,Palanichamy,Murugesan
-
experimental part
p. 299 - 303
(2011/07/31)
-
- Iron(III) tosylate in the preparation of dimethyl and diethyl acetals from ketones and β-keto enol ethers from cyclic β-diketones
-
An efficient method for conversion of ketones to their corresponding dimethyl and diethyl acetals and of cyclic β-diketones into β-keto enol ethers using Fe(OTs)3 as a catalyst is described. Copyright Taylor & Francis Group, LLC.
- Mansilla, Horacio,Afonso, Maria M.
-
p. 2607 - 2618
(2008/12/22)
-
- Regioselective alkene carbon-carbon bond cleavage to aldehydes and chemoselective alcohol oxidation of allylic alcohols with hydrogen peroxide catalyzed by [cis-Ru(II)(dmp)2(H2O)2] 2+ (dmp = 2,9-dimethylphenanthroline)
-
(Chemical Equation Presented) [cis-Ru(II)(dmp)2(H 2O)2]2+ (dmp = 2,9-dimethylphenanthroline) was found to be a selective oxidation catalyst using hydrogen peroxide as oxidant. Thus, primary alkenes were very efficiently oxidized via direct carbon-carbon bond cleavage to the corresponding aldehydes as an alternative to ozonolysis. Secondary alkenes were much less reactive, leading to regioselective oxidation of substrates such as 4-vinylcyclohexene and 7-methyl-1,6-octadiene at the terminal position. Primary allylic alcohols were chemoselectively oxidized to the corresponding allylic aldehydes, e.g., geraniol to citral.
- Kogan, Vladimir,Quintal, Miriam M.,Neumann, Ronny
-
p. 5039 - 5042
(2007/10/03)
-
- Cobalt(II)-catalyzed chemoselective synthesis of acetals from aldehydes
-
The acetalization of aldehydes has been studied with methanol, ethanol, and 2-propanol using CoCl2 in high yields under reflux conditions. The reaction is simple, efficient, chemoselective and does not involve any other additive.
- Velusamy, Subbarayan,Punniyamurthy
-
p. 4917 - 4920
(2007/10/03)
-
- Studies in selectivity aspects in the synthesis of aliphatic α-bromoaldehydes
-
A highly selective process scheme was developed to synthesize α-bromoaldehydes by regulating the important process parameters from a reaction-engineering point of view. Thus, α-bromobutyraldehyde and α-bromoheptaldehyde were synthesized in very high selec
- Mukhopadhyay, Sudip
-
p. 480 - 484
(2013/09/08)
-
- Reactions of N-methyl-2-phenylindole with malondialdehyde and 4- hydroxyalkenals. Mechanistic aspects of the colorimetric assay of lipid peroxidation
-
Under specific acidic conditions, both malondialdehyde (1, MDA) and 4- hydroxynonenal (2, 4-HNE) react with N-methyl-2-phenylindole (3) to give the same chromophoric cyanine 4 with maximal absorbance at 586 nm. Under such conditions, the reaction of 3 with 4-HNE (2) as well as with alkanals yields a second chromophoric cyanine 10 with maximal absorbance at 505 nm. The influence of different acids, iron(III), and oxygen on the reaction of 3 with such aldehydes was studied in detail. Under anaerobic conditions, the acid- induced reaction of 4-HNE with 3 afforded three rapidly interconverting intermediates, 5-7. Their subsequent fragmentation to 4 and hexanal in the presence of iron(III) and oxygen is consistent with the tandem β- fragmentation of an indolyl radical cation. 1-Indolylalkenes were identified as essential intermediates in the acid-induced reaction of 3 with alkanals. A very mild iron(III)catalyzed fragmentation of these intermediates afforded the corresponding 3-formylindole 11 as the direct precursor of the 505 nm chromophore 10. Such reactions were markedly influenced by the nature of the acid. Contrary to the rapid chromogenic reaction of 4-HNE which was observed in the presence of methanesulfonic acid, the HCl-induced reaction of 4-HNE with 3 did not afford the 586 nm chromophore. Furthermore, hexanal did not yield the 505 nm chromophore 10 upon reaction with 3 in the presence of HCl, again in contrast with the rapid chromogenic reaction which was observed in the presence of methanesulfonic acid. Comparison of the reaction mixtures under the two assay conditions confirmed that the same intermediates were formed. We conclude that the nature of the acid plays a crucial role in the oxidative fragmentation of intermediates into chromophores, allowing the selective assay of MDA in the presence of 4-HNE, using HCl acidic conditions.
- Erdelmeier, Irene,Gerard-Monnier, Dominique,Yadan, Jean-Claude,Chaudiere, Jean
-
p. 1184 - 1194
(2007/10/03)
-
- Use of mesoporous MCM-41 aluminosilicates as catalysts in the preparation of fine chemicals: A new route for the preparation of jasminaldehyde with high selectivity
-
α-n-Amylcinnamaldehyde (Jasminaldehyde) has been prepared with high selectivity and using low ratios of benzaldehyde/heptanal by means of mesoporous molecular sieve catalysts and a process which involves the acetalization of heptanal with methanol, followed, in the same pot, by a slow hydrolysis of dimethylacetal and the aldolic condensation of the two aldehydes as the final step. A large pore zeolite (Beta) as well as mesoporous silica-aluminas with regular pore sizes such as MCM-41 and SAM have been used as catalysts. The results indicate that mesoporous silica-aluminas with a very narrow range of pore diameter such as MCM-41 are the most adequate catalysts to produce in one pot the three consecutive reactions, avoiding in a very large extent the self-condensation of heptanal and undesired consecutive reactions. This new route allows us to achieve Jasminaldehyde with high selectivity and with a relative high global reaction rates. The influence of the concentration of acid sites on MCM-41, reaction temperature, and molar ratio of the reactants have been also studied.
- Climent,Corma,Guil-Lopez,Iborra,Primo
-
-
- Use of mesoporous MCM-41 aluminosilicates as catalysts in the production of fine chemicals: Preparation of dimethylacetals
-
Dimethylacetals have been prepared by reacting aldehydes with trimethyl orthoformate. Large pore zeolites (HY and beta) as well as mesoporous silica-aluminas with regular pore sizes, such as MCM-41 and SAM, and commercial amorphous silica-alumina with a broader distribution of pore sizes have been used as catalysts. The results indicate that in addition to bridging hydroxyl groups, silanols can also be active for carrying out this reaction. Zeolites are more active than the mesoporous materials, but their activity decays faster. By carrying out the reaction with aldehydes of different molecular sizes it is shown that the MCM-41 mesoporous materials are promising catalysts for their use in the production of fine chemicals which involve bulky reactants or products. Finally, mesoporous catalysts with a very narrow pore size distribution show a better catalytic behavior than others with a broader pore size distribution.
- Climent,Corma,Iborra,Navarro,Primo
-
p. 783 - 789
(2007/10/03)
-
- Investigation of the Dimethyl Acetal Formation during the Ozonization of Alkenes in Methanol
-
Dimethyl acetal formation during the ozonization of olefins in methanol followed by reduction with dimethyl sulfide has been occasionally reported in the literature.This acetalization can be completely suppressed, when the ozonization is carefully monitored by g.l.c. or t.l.c. analysis and stopped immediately after the consumption of the olefin.It was proved that the acetal formation observed earlier is the result of an acid catalysed reaction accelerated by dimethyl sulfide and dimethyl sulfoxide present in the reaction mixture.The acidic catalyst is formic acid formed from methanol by oxidation with excessive ozone.
- Theil, Fritz,Schick, Hans
-
p. 699 - 704
(2007/10/02)
-
- Electro-organic Chemistry. Part 93. Electro-organic Transformation of Aldehydes and Ketones to α-Hydroxylated Acetals Utilizing Mediators and Some Synthetic Uses of the Products
-
Electro-oxidation of aldehydes (R1R2CHCHO) and ketones (R1R2CHCOR3) in methanol containing iodide ion (I-) and KOH gave the corresponding α-hydroxylated acetals in good yields.The first step of this oxidation is explained in terms of the attack of an anodically generated active iodine species 'I+' on enols of R1R2CHCHO and R1R2CHCOR3. α-Hydroxy acetals were useful starting materials as exemplified by reaction with aniline or methyl carbamates in the presence of Lewis acids to afford β-keto amine derivatives.The anodic oxidation of α-hydroxy acetals was also carried out.
- Shono, Tatsuya,Matsumura, Yoshihiro,Inoue, Kenji,Iwasaki, Fumiaki
-
-
- Efficient Electrocatalytical Acetalization of Aliphatic Aldehydes
-
Aliphatic aldehydes are conveniently acetalized by methanol or 1,2-ethanediol at a platinum or carbon anode.The process is electrocatalytic in character.
- Gora, J.,Smigielski, K.,Kula, J.
-
p. 586 - 588
(2007/10/02)
-
- SYNTHESIS OF DIMETHYL ACETALS, DIETHYL ACETALS, AND CYCLIC ACETALS CATALYZED BY AMINOPROPYLATED SILICA GEL HYDROCHLORIDE (APSG*HCl)
-
The aminopropylated Silica-Gel hydrochloride (APSG*HCl) proved to be an efficient catalyst for the rapid conversion of carbonyl compounds in the corresponding acetals with high yields and in mild and selective conditions.In addition to the obvious advantages offered by heterogeneous catalysis, the present method results very useful when the presence of a weakly-acidic function chemically bonded on the catalyst surface (alkyl ammonium salt) is necessary (compounds which contains functions unstable in acidic media).
- Gasparrini, F.,Giovannoli, M.,Misiti, D.,Palmieri, G.
-
p. 1491 - 1500
(2007/10/02)
-
- THIOUREA, A CONVENIENT REAGENT FOR THE REDUCTIVE CLEAVAGE OF OLEFIN OZONOLYSIS PRODUCTS
-
A convenient procedure for the preparation of aldehydes, in good to excellent yields, from suitable olefins by ozonolysis in methanol, followed by exposure of the resulting products to thiourea, is described.
- Gupta, Deepa,Soman, Raghavan,Dev, Sukh
-
p. 3013 - 3018
(2007/10/02)
-
- Ozonolysis of Symmetrically 1,2-Disubstituted Ethylenes in HCl/Methanol Solutions: Acid Catalyzed Reactions of Primary Cleavage Products
-
The ozonolysis of olefins in 1 M anhydrous solutions of hydrogen chloride in methanol at /= 0 deg C was investigated.Upon warm-up of the ozonolysis products, the peroxidic primary fragmentation products were converted into non peroxidic end-products by HCl-catalyzed reactions.Cyclopentene (1a) and cyclohexene (1b), e.g., afforded mixtures of the corresponding α,ω-dialdehydebis(dimethyl acetals) (8), dimethyl α,ω-dicarboxylates (9), and methyl ω-aldehyde dimethyl acetal carboxylates (10).Norbornene (1c) gave a mixture of the correspondingly substituted 1,3-cyclopentane compounds (8c - 10c), phenanthrene (22) gave a mixture of methyl 2'-formyl-2-biphenylcarboxylate (24a), 2,2'-biphenyldicarbaldehyde (24b), and dimethyl 2,2'-biphenyldicarboxylate (24c).A reaction scheme was advanced for the rationalization of the types and the distribution of the products.It was partly substantiated by model reactions.
- Griesbaum, Karl,Neumeister, Joachim
-
p. 2697 - 2706
(2007/10/02)
-
- Reaction of Ozonides with Methanol in the Presence of Chlorosulphonic Acid: Selective Cleavage of the C-O Bond of the Peroxide Bridge
-
The reaction of 1,2,4-trioxolans (ozonides) (1) with methanol in the presence of chlorosulphonic acid gives good yields of products formed via the corresponding α-methoxy hydroperoxides.The order of reactivity of the ozonides, as estimated by periodic measurement of the n.m.r. spectra of a mixture of the ozonide and chlorosulphonic acid in CD3OD, is as follows: (1a), (1b) > (1c), (1d), (1e), (1f), (1g) > (1h).
- Miura, Masahiro,Nojima, Masatomo,Kusabayashi, Shigekazu
-
p. 2909 - 2913
(2007/10/02)
-