- Walter Reppe Revival – Identification and Genesis of Copper Acetylides Cu2C2 as Active Species in Ethynylation Reactions
-
More than six decades after proposing copper acetylide, Cu2C2, as catalytically active species in ethynylation reactions by Walter Reppe, the explosive species have been experimentally identified and investigated during catalysis in detail now. Taking into account specific safety precautions, unequivocal qualitative characterization was achieved by Raman spectroscopy and X-ray powder diffraction of supported copper catalysts Cu/Bi/SiO2 during and after activation and catalysis in comparison to bulk Cu2C2 materials. Quantification of Cu2C2 succeeded by thermal analysis and Raman spectroscopy. Its formation in aqueous suspension is studied starting from copper(II) oxide catalysts including dissolution, reduction and precipitation steps. Copper acetylide formation can be correlated with catalytic performance in the ethynylation of formaldehyde to 1,4-butynediol.
- Bruhm, Tobias,Abram, Andrea,H?usler, Johannes,Thomys, Oliver,K?hler, Klaus
-
-
Read Online
- Tetrabutylammonium tribromide (TBATB) - MeOH: An efficient chemoselective reagent for the cleavage of tert-butyldimethylsilyl (TBDMS) ethers
-
(equation presented) R = H, alkyl or aryl P = TBDMS, TBDPS, THP, DMT TBDMS THP and DMT ethers are efficiently deprotected with tetrabutylammonium tribromide in methanol. The apparent order of stability of different protecting group is phenolic TBDMS > 1° OTBDPS > 2° OTBDMS > 2° OTHP > 1° OTHP > 1° OTBDMS > 1° ODMT. TBDMS ether has been cleaved selectively in the presence of isopropylidine, Bn, Ac, Bz, THP, and TBDPS groups. This method is high yielding, fast, clean, safe, cost-effective, and therefore most suitable for practical organic synthesis.
- Gopinath, Rangam,Patel, Bhisma K.
-
-
Read Online
- Syntheses of 7-Substituted Anthra[2,3- b]thiophene Derivatives and Naphtho[2,3- b:6,7- b']dithiophene
-
7-R-Anthra[2,3-b]thiophene derivatives (1, R = H, Me, i-Pr, or MeO) are prepared in three steps (in average overall yield >50%) starting from (E)-4-RC6H4CH2(HOCH2)C=CI(CH2OH). The latter are commercial or readily prepared from 2-butyne-1,4-diol and ArCH2Cl (both costing 1 cent/mmol) at 10 g scales. These allow for the selective formation of (otherwise unattainable) higher solubility 7-derivatives. Similar methods allow for the preparation of naphtho[2,3-b:6,7-b']dithiophene 2 using equally low-cost starting materials.
- Al-Jumaili, Mustafa A.,Woodward, Simon
-
-
Read Online
- Mechanism and scope of the base-induced dehalogenation of (E)-diiodoalkenes
-
A wide range of nucleophiles have induced the elimination of iodine from (E)-diiodoalkenes to form alkynes under surprisingly mild conditions. The iodide anion is particularly efficient, and can drive the reaction to completion in less than 1 hour at room temperature in a polar aprotic solvent. Detailed investigations have suggested the reaction has a bimolecular polar mechanism. The deiodination reaction can be driven to completion with 1 equiv. of nucleophile and is partially catalytic with substoichiometric amounts of deiodinating reagent. Kinetic analysis of the stoichiometric iodide-induced reaction indicated an overall pseudo-first-order behavior. The reaction exhibited strong solvent effects, with much slower reactions observed in protic solvents than in polar aprotic solvents. The substrate dimethyl (2E)-2,3-diiodo-butene-2-dioate demonstrated orthogonal reactivity for either elimination or hydrolysis, depending on the solvent and nucleophile used. This reaction is a major pathway for all the diiodoalkenes examined, and represents a challenge and an opportunity for using these substrates in organic synthesis.
- Resch, Daniel,Lee, Chang Heon,Tan, Siew Yoong,Luo, Liang,Goroff, Nancy S.
-
-
Read Online
- Room-temperature carbonization of poly(diiododiacetylene) by reaction with Lewis bases
-
Poly(diiododiacetylene) (PIDA) is a conjugated polymer containing an all-carbon backbone and only iodine atom substituents. Adding a Lewis base to the blue PIDA suspension at room temperature leads first to rapid disappearance of the absorption peaks attributed to PIDA, followed more slowly by release of free iodine. The resulting solid material gives a Raman scattering spectrum consistent with graphitic carbon, and it has a much higher conductivity than PIDA itself. Further investigation has led to the discovery of a previously unreported transformation, the reaction of a Lewis base such as pyrrolidine with a trans-diiodoalkene to form the corresponding alkyne. The generality of this iodine elimination further suggests that reaction of PIDA with Lewis bases dehalogenates the polymer, presenting a new method to prepare carbon nanomaterials at room temperature under very mild conditions.
- Luo, Liang,Resch, Daniel,Wilhelm, Christopher,Young, Christopher N.,Halada, Gary P.,Gambino, Richard J.,Grey, Clare P.,Goroff, Nancy S.
-
-
Read Online
- Method for synthesizing propargyl alcohol
-
The method comprises the following steps: taking potassium hydroxide or potassium alcoholate as a catalyst, and reacting with acetylene below 0.15 mpa pressure in an aromatic hydrocarbon or aliphatic hydrocarbon organic solvent to form propinyl alcohol. The reaction end point material is a 'liquid - liquid' two-phase system and is separated by sedimentation. The product is recovered by hydrolysis separation, extraction purification and rectification separation, and the yield of propargol in the product can reach 71% - 73%.
- -
-
Paragraph 0040-0066
(2021/11/21)
-
- Method for preparing 1,4-butynediol
-
The invention discloses a method for preparing 1,4-butynediol. The method comprises the steps that firstly, a copper catalyst is activated to obtain a copper acetylide/bismuth catalyst, acetylene and formaldehyde are subjected to a reaction under the effect of the copper acetylide/bismuth catalyst to obtain a 1,4-butynediol and copper acetylide/bismuth catalyst mixed solution, and in a reaction kettle, the mixed solution is filtered through a metal film filter to obtain a 1,4-butynediol clear solution which is fed outside the reaction kettle to be subjected to follow-up technological treatment to obtain a finished product. In the reaction process, copper acetylide/bismuth catalyst turbid liquid is extracted periodically, then, an equimolar copper acetylide/bismuth catalyst or a copper catalyst is supplemented, a clear solution obtained after the extracted copper acetylide/bismuth catalyst turbid liquid is filtered is subjected to the follow-up technological treatment to obtain a finished product finally, and copper acetylide/bismuth catalyst cakes are subjected to a regeneration procedure to be recycled; the 1,4-butynediol clear solution is adopted for performing back flushing on the metal film filter periodically. Due to periodic extraction and supplementing of the catalyst, production losses caused by frequent stopping are avoided, and the product yield and output are improved.
- -
-
Paragraph 0009
(2017/03/14)
-
- Iodopropynyl a, 1,4-butyne diol and hexamine three cogeneration method for continuous production of
-
The invention discloses a trigeneration continuous production method for propiolic alcohol, 1,4-butinodiol and urotropine, and belongs to the technical field of chemical engineering. According to the method, a formaldehyde aqueous solution (10%-37% wt) and acetylene are taken as raw materials for synthesizing propiolic alcohol and co-producing 1,4-butinodiol and urotropine, the reaction temperature is 80-120 DEG C, the pressure is 1.0-2.5 MPa, and propiolic alcohol with the purity of 99.5% or more, a 1,4-butinodiol aqueous solution and a urotropine aqueous solution are obtained. The conversion rate of formaldehyde in the whole technology is 100%, and the method has the advantages of safety and environment friendliness.
- -
-
Paragraph 0041-0052
(2017/06/19)
-
- METHODS OF PRODUCING DICARBONYL COMPOUNDS
-
Dicarboxylic acids, such as adipic acid, and diesters, such as adipates, may be produced by hydrogenating alkynes that may be produced from raw materials salvaged from waste stream processes. The carbons of the dicarboxylic acids are provided by alkynes generated from biomass waste and carbon dioxide recovered from waste streams such as exhaust gases.
- -
-
Paragraph 0036
(2015/05/06)
-
- PROCESS FOR THE HYDROGENATION OF 1,4-BUTYNEDIOL TO TETRAHYDROFURAN IN THE GAS PHASE
-
The present invention relates to a process for the catalytic hydrogenation of 1,4-butynediol to tetrahydrofuran at at least the decomposition temperature of 1,4-butynediol, wherein 1,4-butynediol is vaporized in a hydrogen-comprising gas stream and is hydrogenated in gaseous form over at least one catalyst, comprising at least one of the elements from groups 7 to 11 of the Periodic Table of the Elements.
- -
-
Page/Page column 9
(2012/07/28)
-
- PROCESS FOR HYDROGENATING 1,4-BUTYNEDIOL TO GIVE MIXTURES COMPRISING TETRAHYDROFURAN, 1,4-BUTANEDIOL AND γ-BUTYROLACTONE IN THE GAS PHASE
-
Process for preparing tetrahydrofuran, 1,4-butanediol and/or gamma-butyrolactone by hydrogenation of 1,4-butynediol, wherein 1,4-butynediol is vaporized in a hydrogen-comprising gas stream and hydrogenated in gaseous form over at least one catalyst which comprises at least one of the elements of groups 7 to 11 of the Periodic Table of the Elements.
- -
-
Page/Page column 9
(2012/07/28)
-
- Method For The Separation Of Polymeric By-Products From 1,4-Butynediol
-
The present invention relates to a process for purifying 1,4-butynediol, which comprises processing 1,4-butynediol in a dynamic mixing apparatus in an inert gas atmosphere at from 25 to 150° C. at a shear rate in the radial gap between rotor and stator of the mixing apparatus of more than 100 000 sec?1, awaiting phase separation at temperatures of from 25 to 150° C. and separating off the bottom phase, and a process for the hydrogenation of 1,4-butynediol to 1,4-butenediol and 1,4-butanediol using the purified 1,4-butynediol.
- -
-
Page/Page column 3
(2008/12/07)
-
- Method for the Separation of Polymeric By-Products from 1,4-Butynediol
-
The present invention relates to a process for purifying 1,4-butynediol, which comprises compressing 1,4-butynediol to from 50 to 1500 bar, depressurizing it, waiting for phase separation to occur after depressurization and separating off the bottom phase, and a process for the hydrogenation of 1,4-butynediol to 1,4-butenediol and 1,4-butanediol using the purified 1,4-butynediol.
- -
-
Page/Page column 3
(2008/12/08)
-
- Deprotection of a silyl group with mesoporous silica
-
The triethylsilyl (TES) group of silyl ethers of several types is selectively and easily removed in the presence of a t-butyldimethylsilyl (TBDMS) group with a mesoporous silica MCM-41/MeOH heterogeneous system. Comparison of the efficiency was carried out among several solvents, and among such promoters as common zeolites and ion-exchange resins. Furthermore, FSM-16, another mesoporous silica, was examined for the possibility of recycling by re-calcination at 400°C after the reaction.
- Itoh, Akichika,Kodama, Tomohiro,Masaki, Yukio
-
p. 861 - 864
(2008/02/11)
-
- METHOD FOR THE PRODUCTION OF PROPARGYL ALCOHOL
-
The invention relates to a method for producing propargyl alcohol by reacting an aqueous formaldehyde solution containing acetylene on a catalyst comprising copper acetylide at an operating pressure of 1 to 15 bar and a temperature of 70 to 120 °C without forming a continuous gas phase. According to the inventive method, the aqueous formaldehyde solution contains an organic solvent for acetylene while the catalyst is located in a fluid bed.
- -
-
Page/Page column 7; 8
(2008/06/13)
-
- Efficient tetrahydropyranylation of alcohols and detetrahydropyranylation reactions in the presence of catalytic amount of trichloroisocyanuric acid (TCCA) as a safe, cheap industrial chemical
-
Preparation and cleavage of THP ethers of different hydroxy functional groups are easily and efficiently performed in the presence of trichloroisocyanuric acid (TCCA) in the absence of solvent with high yields.
- Firouzabadi, Habib,Iranpoor, Nasser,Hazarkhani, Hassan
-
p. 3623 - 3630
(2007/10/03)
-
- A catalytic amount of nickel(II) chloride hexahydrate and 1,2-ethanedithiol is a good combination for the cleavage of tetrahydropyranyl (THP) and tert-butyldimethylsilyl (TBS) ethers
-
Various THP and TBS ethers can be unmasked easily to the corresponding hydroxyl compounds in good yields by using a combination of a catalytic amount of nickel(II) chloride hexahydrate and 1,2-ethanedithiol at room temperature. In addition, alkyl TBS ethers can be hydrolyzed chemoselectively in the presence of aryl TBS ethers. Moreover, alkyl TBS ethers can be cleaved easily in the presence of alkyl or aryl THP ethers using the same conditions.
- Khan, Abu T.,Islam, Samimul,Choudhury, Lokman H.,Ghosh, Subrata
-
p. 9617 - 9621
(2007/10/03)
-
- A simple and useful synthetic protocol for selective deprotection of tert-butyldimethylsilyl (TBS) ethers
-
A wide variety of tert-butyldimethylsilyl ethers 1 can be easily cleaved to the corresponding parent hydroxyl compound 2 in the presence of 5 mol % of acetonyltriphenylphosphonium bromide (ATPB) at room temperature. In addition, tert-butyldiphenylsilyl ethers can also be cleaved by using 20 mol % of the same catalyst. Alkyl tert-butyldimethylsilyl ethers can be deprotected to the hydroxyl compounds chemoselectively in the presence of aryl tert- butyldimethylsilyl ethers. Some of the major advantages are mild reaction conditions, no aqueous workup, high efficiency and chemoselectivity and compatibility with other protecting groups; no brominations occur in the aromatic ring under these experimental conditions. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.
- Khan, Abu T.,Ghosh, Subrata,Choudhury, Lokman H.
-
p. 2198 - 2204
(2007/10/03)
-
- A highly efficient and useful synthetic protocol for the cleavage of tert-butyldimethylsilyl (TBS) ethers using a catalytic amount of acetyl chloride in dry methanol
-
A wide variety of tert-butyldimethylsilyl (TBS) ethers as well as tert-butyldiphenylsilyl (TBDPS) ethers 1 can be easily deprotected to the corresponding parent hydroxyl compounds 2 by employing catalytic amounts of acetyl chloride in dry MeOH at 0°C to room temperature in good yields. Some of the major advantages are mild conditions, high efficiency, high selectivity, high yields, easy operation, and also compatibility with other protecting groups. Furthermore, no acetylation nor chlorination takes place under the experimental conditions.
- Khan, Abu T.,Mondal, Ejabul
-
p. 694 - 698
(2007/10/03)
-
- Preparation, structure, and unique thermal [2 + 2], [4 + 2], and [3 + 2] cycloaddition reactions of 4-vinylideneoxazolidin-2-one
-
The terminal allene Cα=Cβ bonds of 4-vinylidene-2-oxazolidinone (2) readily undergo [2 + 2] cycloaddition with a wide variety of terminal alkynes, alkenes, and 1,3-dienes irrespective of their electronic nature under strictly thermal activation conditions (70-100°C) and provide 3-substituted (Z)-methylenecyclobutenes 6, 3-substituted methylenecyclobutanes 7 and 8, and 3-vinylmethylenecyclobutanes 9, respectively, in good to excellent yields. Alkenes react with 2 with complete retention of configuration. The [2 + 2] cycloaddition is concluded to proceed via a concerted [(π2s + π2s)allene + π2s] Hueckel transition state on the basis of experimental evidences and quantum mechanical methods. Some highly polarized enones and nitrile oxide, on the other hand, react with 2 selectively at the internal C4=Cα double bonds and give spiro compounds 10 and 11, respectively. The bent allene bonds (173-176°) and the unique reactivity associated with 2 are attributed to a low-lying LUMO (Cα=Cβ) that is substantiated by a through-space σ*(N-SO2)-π*(Cα= Cβ) orbital interaction.
- Horino, Yoshikazu,Kimura, Masanari,Tanaka, Shuji,Okajima, Toshiya,Tamaru, Yoshinao
-
p. 2419 - 2438
(2007/10/03)
-
- Preparation of alkynediols
-
The process for preparing alkynediols of the formula (I) R1R2C(OH)—C≡C—C(OH)R1R2??(I) where R1, R2are each independently H, or a C1-20-hydrocarbon radical which may be substituted by one or more C1-6-alkyls and/or be interrupted by nonadjacent heteroatoms and/or contain C—C double or triple bonds, by reacting compounds of the formula (II) R1—C(═O)—R2??(II) with acetylene in a polar aprotic solvent is carried out in the presence of basic alkali metal salts as catalysts.
- -
-
Page column 2, 3
(2010/11/29)
-
- Tetrabutylammonium tribromide (TBATB)-promoted tetrahydropyranylation/depyranylation of alcohols
-
Alcohols are tetrahydropyranylated rapidly in high yields in the presence of a catalytic amount of TBATB in dichloromethane at room temperature. Depyranylation to their parent alcohol is achieved in quantitative yields by merely changing the solvent to methanol.
- Naik, Sarala,Gopinath, Rangam,Patel, Bhisma K
-
p. 7679 - 7681
(2007/10/03)
-
- Selective deprotection of triethylsilyl group in the presence of t-butyldimethylsilyl group with MCM-41/MeOH heterogeneous system
-
Triethylsilyl (TES) group of silyl ethers of several types is selectively and easily removed in the presence of t-butyldimethylsilyl group (TBS) with a mesoporous silica MCM-41/MeOH heterogeneous system. Comparison of the efficiency was carried out among several solvents, and among such promoters as common zeolites and ion-exchange resins. Thieme Stuttgart.
- Itoh, Akichika,Kodama, Tomohiro,Masaki, Yukio
-
p. 357 - 359
(2007/10/03)
-
- Reductive dehalogenation of aliphatic vic-dihalides with metallic samarium in a methanolic medium
-
In the title reaction, eight vic-dibromides and three vinylene dibromides gave the corresponding debromination products (alkenes and alkynes) at room temperature under neutral condition and an argon atmosphere. 2,3-Dibromosuccinic acid derivatives gave overreduction products or an unusual coupling dimer.
- Yanada, Reiko,Negoro, Nobuyuki,Yanada, Kazuo,Fujita, Tetsuro
-
p. 9313 - 9316
(2007/10/03)
-
- Unique Template Effects of Distannoxane Catalysts in Transesterification of Diol esters
-
1,n-Diol diacetates (n = 2,3,4) are selectively converted into the corresponding monoacetates by distannoxane-catalyzed transesterification.Such unique selectivity is not encountered with 1,n-diol diacetates where n>/=5.A great difference in reactivity is also seen in the transesterification between methyl butyrate and 1,n-diol monoacetates: the ethylene glycol derivative sluggishly undergoes transesterification whereas higher homologs react smoothly.The unique template effects of the catalysts are discussed in terms of cooperation of two different tin atoms which are located in the proximity.
- Otera, Junzo,Dan-oh, Nobuhisa,Nozaki, Hitosi
-
p. 3065 - 3074
(2007/10/02)
-
- Biodegradable optically active polymers and intermediate oligomers thereof, and process for producing them
-
An optically active oligomer obtained by polycondensation of an (R)-3-hydroxyalkanoic acid alkyl ester and a diol, a diamine and/or an amino alcohol may be copolymerized with monomer selected from diisocyanic acid esters, dicarboxylic acid derivatives, and dichlorosilanes to give an optically active polymer. The functional thermoplastic polymers so produced (polyesters, polyetherpolyesters, polyester-polyurethanes and polyester-polyether-polyurethanes) are biodegradable and hydrolyzable, and lend themselves to industrial production.
- -
-
-
- Mechanism for the Hydrolytic Degradation of Barban to 3-Chloroaniline
-
4-Chloro-2-butynyl N-(3-chlorophenyl)carbamate (Barban) is a herbicide whose alkaline hydrolysis leads quantitatively to 3-chloroaniline, after releasing the chlorine atom from the ester group.The dechlorination step proceeds via a nucleophilic substitution reaction of the type SN2-SN2', corresponding to an attack by hydroxide ion at the carbon atoms that are α and γ to the chlorine atom.The 4-hydroxy-2-butynyl and 2-oxo-3-butenyl N-(3-chlorophenyl)carbamates thus formed are hydrolysed to the N-(3-chlorophenyl)carbamic acid which, on decarboxylation, gives 3-chloroaniline.
- Bergon, M.,Kouda-Bonafos, M.,Calmon, J. P.
-
p. 1915 - 1920
(2007/10/02)
-
- Preparation of tetrahydrofuran
-
Tetrahydrofuran is prepared from a crude alkaline aqueous solution of butane-1,4-diol, as obtained by reaction of acetylene with aqueous formaldehyde and catylytic hydrogenation of the resulting but-2-yne-1,4-diol solution by a process in which the alkaline solution is first neutralized with sulfuric acid and water is then eliminated in the liquid phase at from 200° to 260° C., under superatmospheric pressure and in the presence of phosphoric acid.
- -
-
-
