- Strontium chloride modified Nieuwland catalyst in the dimerization of acetylene to monovinylacetylene
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SrCl2 was used as a co-catalyst of CuCl in Nieuwland catalyst and CuCl as the main catalyst, NH4Cl as the solubilizer, water as the solvent and a certain amount of hydrochloric acid, thereby forming Sr-Cu bimetallic cooperative catalysis reaction systems for C2H2 dimerization. Under the optimum condition, the acetylene conversion is 13 % and monovinylacetylene selectivity can reach to 94 %.
- Lu, Jun-Long,Xie, Jian-Wei,Liu, Hai-Yue,Liu, Ping,Liu, Zhi-Yong,Dai, Bin
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Read Online
- Addition of Chloroprene Grignards to Aromatic Aldehydes: Synthesis of Homoallenyl Alcohols
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A general procedure for the one-pot synthesis of racemic homoallenyl alcohols from the corresponding aldehyde and chloroprene-derived Grignards is described. Employing bis[2-dimethylaminoethyl]ether (BDMAEE) as an additive at low temperatures shifts the selectivity of the chloroprene Grignard addition to aldehydes such that it is almost exclusive toward allene formation. In a set of follow-up experiments, simple and more elaborate methods for further derivatization have been demonstrated, allowing quick access to more complex structures.
- Geissler, Arne G. A.,Breit, Bernhard
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supporting information
p. 2621 - 2625
(2021/04/12)
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- Thermal ring opening of 1,1-dibromo and 1-bromo-2- chloromethylcyclopropanes: Observation of a formal debromochlorination
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When the title compounds are thermolyzed in the gas phase under vacuum or in hot quinoline, several products are formed. A predominant product in all cases is a chlorine-free buta-1,3-diene which has been formed by formal debromochlorination, a reaction n
- Sydnes, Leiv K.,Alnes, Karl F. S.,Pettersen, Anita,Brinker, Udo H.
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experimental part
p. 479 - 483
(2010/06/16)
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- Gas phase surface-catalyzed HCl addition to vinylacetylene: motion along a catalytic surface. Experiment and theory
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Gaseous mixtures of HCl and vinylacetylene were permitted to react in Pyrex IR cells (NaCl windows). Gaseous 4-chloro-1,2-butadiene and 2-chloro-1,3-butadiene (chloroprene) were the major products. Kinetic data (FTIR) generated a rate expression in concert with surface catalysis. Computational studies involving surface associated water provide a view that accounts for the experimentally determined orders and a bifurcated pathway producing both products. The results are in accord with wall-adsorbed reactant(s) as well as previously reported computational studies on the reactants.
- Mascavage, Linda M.,Zhang-Plasket, Fan,Sonnet, Philip E.,Dalton, David R.
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p. 9357 - 9367
(2008/12/23)
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- Synthesis of the potent anticancer agents ottelione A and ottelione B in both racemic and natural optically pure forms
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(Chemical Equation Presented) The powerful antitumor agents ottelione A and B were synthesized in racemic form by a method that relies on selective ring closing metathesis. Optically pure natural (+)-ottelione A was then made from D-ribose, via an α-keto cyclopropane. A key feature of the route is that the cyclopropyl group controls the stereochemistry in the attachment of the ArCH2 unit and is then converted by the action of SmI2 into a vinyl group, so that the substituents on the resulting five-membered ring have the required trans relationship. Epimerization of an intermediate gave access by the same method to the trans ring fused isomer (-)-ottelione B.
- Clive, Derrick L. J.,Liu, Dazhan
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p. 3078 - 3087
(2008/09/19)
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- In vitro metabolism of chloroprene: Species differences, epoxide stereochemistry and a de-chlorination pathway
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Chloroprene (1) was metabolized by liver microsomes from Sprague-Dawley rats, Fischer 344 rats, B6C3F1 mice, and humans to the monoepoxides, (1-chloro-ethenyl)oxirane (5a/5b), and 2-chloro-2-ethenyloxirane (4a/4b). The formation of 4a/4b was inferred from the identification of their degradation products. With male Sprague-Dawley and Fischer 344 rat liver microsomes, there was a ca. 3:2 preference for the formation of (R)-(1-chloroethenyl)oxirane (5a) compared to the (S)-enantiomer (5b). A smaller but distinct enantioselectivity in the formation of (S)-(1-chloro-ethenyl)oxirane occurred with liver microsomes from male mouse (R:S, 0.90:1) or male human (R:S, 0.86:1). 2-Chloro-2-ethenyloxirane was very unstable in the presence of the microsomal mixture and was rapidly converted to 1-hydroxybut-3-en-2-one (11) and 1-chlorobut-3-en-2-one (12). An additional rearrangement pathway of 2-chloro-2-ethenyloxirane gave rise to 2-chlorobut-3-en-1-al (14) and 2-chlorobut-2-en-1-al (15). Further reductive metabolism of these metabolites occurred to form 1-hydroxybutan-2-one (17) and 1-chlorobutan-2-one (18). In the absence of an epoxide hydrolase inhibitor, the microsomal incubations converted (1-chloroethenyl)oxirane to 3-chlorobut-3-ene-1,2-diol (21a/21b). When microsomal incubations were supplemented with glutathione, 1-hydroxybut-3-en-2-one was not detected because of its rapid conjugation with this thiol scavenger.
- Cottrell,Golding,Munter,Watson
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p. 1552 - 1562
(2007/10/03)
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- Process for preparing chloroprene
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Process for preparing chloroprene by dehydrochlorinating 3,4-dichloro-1-butene in the presence of lime and a polyol, such as a glycol selected from (poly)ethylene glycol and (poly)propylene glycol or sugars, with ethylene glycol being preferred.
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- Process for preparing 1,4-dihydroxy, 5,8-dihydronaphthalene and related compounds
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1,4-dihydroxy, 5,8-dihydronaphthalene and related compounds are provided from benzoquinone, and 1,3-butadiene which may be substituted with halogen, acyl, and alkyl, in a one step reaction in the presence of a ferric salt catalyst.
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- Phenylselenium Trichloride in Organic Synthesis. Reaction with Unsaturated Compounds. Preparation of Vinylic Chlorides via Selenoxide Elimination
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Phenylselenium trichloride, PhSeCl3, was reacted with a number olefinic compounds to produce (β-chloroalkyl)phenylselenium dichlorides.The addition was anti stereospecific and irreversible.The presence of an oxygen substituent (acyloxy or aryloxy group) in the allylic position of the olefin directed the attack of PhSeCl3 to occur regiospecifically anti-Markovnikov to give a (β-acyloxy/aryloxy-β'-chloroalkyl)phenylselenium dichloride.When the (β-chloroalkyl)phenylselenium dichlorides were treated in methylene chloride with aqueous sodium hydrogen carbonate, the selenium dichloride moiety was readily hydrolyzed to a selenoxide, which underwent the usual selenoxide elimination reaction to produce an allylic or a vinylic chloride.Symmetrical olefins containing no allylic hydrogens were converted to vinylic chlorides with retention of olefin geometry.Olefins containing a directing oxygen substituent in the allylic position afforded vinylic chlorides where the vinylic halogen atom was oriented 1,3 to the oxygen substituent (E/Z mixture).Other olefins afforded mixtures of allylic and vinylic halides in varying proportions.The reaction of phenyselenium tribromide, PhSeBr3, with some olefinic compounds was also investigated.This material showed the same stereo- and regiochemical behavior as PhSeCl3 in its addition reactions.However, the adducts were not useful for the preparation of vinylic or allylic bromides by using the hydrolytic selenoxide elimination reaction.
- Engman, Lars
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p. 4086 - 4094
(2007/10/02)
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- Thermolysis of vinyl chloride in nitrogen; rates and products between 601-681 deg C
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In a 10-15-fold excess of nitrogen, at normal pressure and with τ ca. 3 s, decomposition of vinyl chloride (VC) sets in at about 550 deg C.At 680 deg C about 35percent decomposition takes place.Major products in this region are HCl, acetylene, 2-chlorobutadiene and vinylacetylene (1-buten-3-yne).At higher temperatures formation of tar and soot becomes increasingly important.A reaction mechanism in accord with the experimental facts is proposed and analyzed via thermochemical kinetics.Free-radical chain processes play a major part, with Cl. leads to.CH=CHCl and CH2=C.Cl radicals, respectively.Their relative rate of formation on a per-H basis is ca. 1/5 around 620 deg C.The former lose Cl. to give acetylene.The latter add to VC which leads to 2-chlorobutadiene irrespective of the site of addition (Scheme 1).Various routes to vinylacetylene are discussed.The formation of other (minor) products such as ethylene and methyl chloride is also rationalized.Added HCl is seen to increase the acetylene/2-chlorobutadiene product ratio with little effect on the rate of conversion of VC.This is due to reversal of the reaction leading to CH2=C.Cl radicals, through H-atom transfer from HCl.
- Manion, Jeffrey A.,Louw, Robert
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p. 442 - 448
(2007/10/02)
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- MECHANISMS OF BY-PRODUCT FORMATION IN THE DEHYDROCHLORINATION OF 1,2-DICHLOROETHANE.
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The decomposition of 1,2-dichloroethane (DCE) to vinyl chloride (VC) was studied in the temperature range 620-750 K at DCE partial pressures of 50-450 Torr. Initiation of the radical chain reaction by a XeCl laser allowed controlled degree of conversion which had a strong influence on the formation of the major by-products acetylene and 2-chlorobutadiene. Both compounds are formed via abstraction of olefinic hydrogen from vinyl chloride by Cl atoms. Analysis of the product distribution combined with calculations yielded kinetic data of these side reactions. The mechanism was confirmed by adding HCl and vinyl chloride to the substrate. Formation of other by-products products by homogeneous processes and the photolysis of vinyl chloride are discussed.
- Schneider,Wolfrum
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p. 1058 - 1062
(2007/10/02)
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- Alkynes and Cumulenes, XVII, Photoaddition of Vinylacetylene to other Unsaturated Hydrocarbons
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On irradiation in the presence of triplet sensitizers, vinylacetylene (1) may be added with its double bond to olefins , dienes , allenes , and diynes .The resulting multifunctionalized cyclobutane derivatives are characterized by spectroscopic and chemical methods.Since the ethinyl group of these codimers may be hydrated to the acetyl function, 1 represents a photochemical equivalent of methyl vinyl ketone which itself does not undergo the described photoadditions.When benzene (56) is employed as addition partner the primary product of the codimerisation, 54, isomerizes to vinylcyclooctatetraene (55).
- Siegel, Herbert,Eisenhuth, Ludwig,Hopf, Henning
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p. 597 - 612
(2007/10/02)
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- Process for producing haloprene
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Process for producing halogenated butadienes by the dehydrohalogenation of a dihalobutene in the presence of caustic and an anionic surface active agent.
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- Process for the production of 2-chlorobutadiene-1,3 from 3,4-dichlorobutene-1
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A process is described whereby 2-chlorobutadiene-1,3 is produced from 3,4-dichlorobutene-1 in a two-phase reaction system wherein the reaction predominantly occurs in the organic phase and the production of undesirable by-products, particularly 1-chlorobutadiene-1,3 and acetaldehyde, is suppressed. The practice of the process results in a brine effluent from the reactor containing small amounts of organic materials resulting in a waste product which is less polluting and more easily cleaned. The organic phase is selected from primary and secondary alcohols, alkoxyethanols and mixtures thereof, preferably alkoxyethanols wherein the alkyl group has two or more carbon atoms. Surprisingly, I have discovered that the selection of the organic phase of the reaction system is made by a screening test wherein a two-phase system of a 20% brine and 3,4-dichlorobutene-1 is prepared and the alcohol or alkoxyethanol being investigated is added to obtain equilibrium in the system. Materials selected as the organic phase material are selected from those where the product of the weight percent water in the organic phase and weight percent alcohol being investigated in the organic phase is greater than 200.
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