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Pressure acetylene under

Acetylene is condensed with carbonyl compounds to give a wide variety of products, some of which are the substrates for the preparation of families of derivatives. The most commercially significant reaction is the condensation of acetylene with formaldehyde. The reaction does not proceed well with base catalysis which works well with other carbonyl compounds and it was discovered by Reppe (33) that acetylene under pressure (304 kPa (3 atm), or above) reacts smoothly with formaldehyde at 100°C in the presence of a copper acetyUde complex catalyst. The reaction can be controlled to give either propargyl alcohol or butynediol (see Acetylene-DERIVED chemicals). 2-Butyne-l,4-diol, its hydroxyethyl ethers, and propargyl alcohol are used as corrosion inhibitors. 2,3-Dibromo-2-butene-l,4-diol is used as a flame retardant in polyurethane and other polymer systems (see Bromine compounds Elame retardants). [Pg.393]

Among various other ways of cyclizing 3-aminopropan-l-ol to a tetrahydro-1,3-oxazine derivative, an interesting reagent is acetylene under pressure ... [Pg.315]

Attempts to prepare 5-vinyl-5F7-dibenz[b,/]azepine by alkylation of 5i/-dibenz[b,/]azepine with 2-chloroethyl-p-toluenesulfonate followed by dehydrochlorination, or by direct vinylation with acetylene under pressure in toluene or in dimethyl sulfoxide, have failed.194 Also, 5H-dibenz[b,/]azepine fails to react with acryloyl chloride, although the 5-acryloyl derivative 8 (R = COCH = CH2 mp 122 — 123 C) has been prepared in 65% yield by condensing dibenz-azepine 5 with 3-chloroacryloyl chloride, followed by dehydrochlorination of the product with l,8-diazabicyclo[5.4.0]undec-7-ene in dimethyl sulfoxide at 80-90°C.194... [Pg.264]

Crospovidone is a cross-linked homopolymer of A-vinyl-2-pyrrolidone. Acetylene and formaldehyde react to form butynediol. Hydrogenation and subsequent cyclodehydrogenation gives butyrolactone. The reaction of butyrolactone with ammonia produces pyrrolidone, which is vinylated with acetylene under pressure. The linear polymerization of the vinylpyrrolidone yields polyvinylpyrrolidone, a soluble binder, whereas the popcorn (branched) polymerization yields crospovidone, an insoluble... [Pg.270]

Tertiary amines react with acetylene under pressure to give quaternary vinylammonium hydroxides [82a, b] (Eq. 29). [Pg.57]

The most general commercial process for the manufacture of mono-and divinyl ethers, developed by Reppe m the 1930s at BASF, is by treating alcohols with acetylene under pressure of >6.8 atin (100 psi) at temperatures of 120-180 0 in the presence of catalytic amounts of the corresponding metal alcoholate, The danger of handling acetylene under pressure in concentrated form requires sophisticated equipment and should only be attempted experimentally in an appropriately barricaded high pressure autoclave,... [Pg.1689]

In general, however, methyl 1-naphthyl ketoxime starts to condense with acetylene under pressure at about 60°C. At 80°C (3 hr, KOH) 2-(l-naphthyl)- 1-vinylpyrrole (15) becomes the predominant reaction product, however its yield decreases due to resinification on further elevating the temperature and increasing the reaction time. 2-(l-Naphthyl)pyrrole (14), free from the corresponding N-vinylpyrrole (15), was isolated in 22% yield when use was made of a catalytic pair LiOH/DMSO (90°C, 3 hr). The temperature effect (3 hr, 30% KOH, initial acetylenic pressure of 12 atm) on the yield of naphthylpyrroles was examined in condensation of methyl 2-naphthyl ketoxime with acetylene as an example (82KGS1351) ... [Pg.214]

The oxime of 2-acetylcoumarone 33 poorly reacted with acetylene under pressure, O-vinyl oxime 34 and 2-(pyrrol-2-yl)coumarone (35) being obtained in 22% and 24% yields, respectively (Scheme 6) (05CHE444). [Pg.216]

Dimethylglyoxime 40 with acetylene under pressure in KOH-DMSO gave 2-[2 -(6 -methylpyridyl)]-N-vinylpyrrole (41) (36%) along with the expected 0-vinyl oxime 42 (10%), 2-acetylpyrrole 43 (18%) and dipyrrole 44 (15%) (Equation (11)) (01MC74). [Pg.217]

Divinyl-2,2 -dipyrrole 61 was obtained from 3,4-hexanedione dioxime (62) with acetylene under pressure (Equation (18)). In the case of 1,2-cyclohex-anedione dioxime (63), 2,2 -dipyrrole 64, 2-pyridyl- (65) and 2-acylpyrroles 66 were isolated (Equation (19)) (06CHE34). Dioximes 67 and 68 gave their mono- (69 and 70) and divinyl derivatives 71 and 72, mostly 3,4-diphenyl-(73) and 3,4-di(furan-2-yl)-l,2,5-oxadiazoles 74 (Equation (20)). [Pg.219]

Dioximes of hexane-2,5-dione (81) and cyclohexane-1,4-dione (82) reacted with acetylene under pressure to give dipyrrole 83 and 1,5-divinyl-4,8-dihydropyrrolo[2,3-/]indole (84) in 12% and 6% yields, respectively, thus exemplifying a very simple, straightforward route to inaccessible or unknown pyrrolic assemblies (Equation (22)) (04TL3789). [Pg.220]

Acetylene is condensed to vinylacetylene and divinylacetylene by cuprous chloride and ammonium chloride. Similar additions of other compounds containing an active hydrogen atom occur in the presence of various catalysts. Mercury salts ate most effective in the vapor-phase reaction of acetylene with hydrogen chloride to give vinyl chloride (100%). Basic catalysts such as potassium hydroxide, potassium ethoxide, or zinc oxide are used for the vinylation of alcohols, glycols, amines, and acids. Most of these reactions involve the use of acetylene under pressure, and few have been described as simple laboratory procedures. Chloroacetic acid, however, reacts with acetylene at atmospheric pressure in the presence of mercuric oxide to yield vinyl chloro-acetate (49%). ... [Pg.476]

Bernasconi et aL (1995), and Bernasconi et al. (1996). An example of a relevant phase transition is the polymerization of acetylene under pressure (Bernasconi et aL, 1997). [Pg.386]

Whereas olefins react with nucleophiles only when polarized by an electron-attracting group, the acetylene bond is susceptible to nucleophilic attack without such stimulus.193,194 In the presence of alkaline catalysts alcohols and acetylenes under pressure give vinyl ethers (vinylation) 195... [Pg.297]

At the end of the 1920 s, Walter Reppe (29, 30, 31, 32) started his experiments on catalytic reactions with acetylene under pressure. On the basis of his studies, which soon were known all over the world as Reppe chemistry, it was possible to construct complicated organic compounds of high value from simple building stones. From the standpoint of the chemical engineer the greatness of his achievement was that the... [Pg.258]

Dimethyl-1,2,4-triazole is a colorless solid with a melting point of 144°C. 1-Vinyl-1,2,4-triazole can be prepared by the reaction of 1,2,4-triazole with acetylene under pressure under alkaline conditions. Benzo-triazole can exist in two tautomeric forms as shown in Figure 9.1. [Pg.301]

Bemasconi M, Chiarotti G, Focher P, Partinello M, Tosatti E (1997) Solid-state polymerization of acetylene under pressure ab initio simulation. Phys Rev Lett 78 2008-2011... [Pg.96]

Aoki, K., Kakudate, Y, Yoshida, M., Usuba, S., Tanaka, K., and Fujiwara, S., Solid-state polymerization of acetylene under pressure, Synth. Met., 28, D91-98 (1989). [Pg.327]

Acetylene can be liquefied and solidified with relative ease. However, in both the liquid and solid states, acetylene is shock sensitive and explodes with extreme violence when ignited. For this reason, DOT and TC regulations prohibit the shipment of liquid or solidified acetylene. A mixture of gaseous acetylene with air or oxygen in certain proportions explodes if ignited. Gaseous acetylene under pressure may... [Pg.226]

The avoidance of the dangerous working with acetylene under pressure, requiring special techniques for safe handing [581, 582], in particular lowers the cost of the end products. [Pg.121]

Anotlier version of the reaction using excess acetylene under pressure has been developed to increase selectivity relative to N-vinylpyrroles [182]. The synthesis of N-vinylpyrroles is accomplished as follows a heated (70°C) mixture of ketone, NH20H-HC1 and NaHCOj in DMSO was blown with argon, and after adding KOH, treated with acetylene in autoclave at 100-120°C. [Pg.13]

Dihydrobenz[e]indole and its vinyl derivative have been synthesized via the three-component reaction of 2-tetralone, hydroxylamine, and acetylene under pressure in the MOH/DMSO systems (Scheme 1.17) [183]. [Pg.13]

Oxime of 1-acetyladamantane reacts with acetylene under pressure (13 atm) to give 0-vinyl oxime (80% yield) [130], which upon heating (DMSO, 120°C, 1 h) rearranges to 2-(l-adamantyl)pyrrole (83% yield). 1-Acetyladamantane and adamantane are the side products of this reaction (Scheme 1.24). [Pg.16]

The annulation of steroid skeleton with N-vinylpyrrole fragment is accomplished via the reaction of A5-cholesten-3-one oxime with acetylene under pressure in the system KOH/DMSO (120°C, 30 min. Scheme 1.41) [213]. The pyrrolization... [Pg.51]

Recently, a novel modification of the reaction has been developed to selectively synthesize 2-(l-naphthyl)-N-vinyl- and 2-(2-naphthyl)-N-vinylpyrroles (Scheme 1.50). According to the protocol, oximates are preformed from the corresponding oximes and sodium hydroxide in DMSO followed by their treatment with acetylene under pressure (120 C, 1 h) [226]. The yields of N-vinylpyrroles are 61% and 64%, respectively [226]. [Pg.57]


See other pages where Pressure acetylene under is mentioned: [Pg.106]    [Pg.514]    [Pg.101]    [Pg.119]    [Pg.308]    [Pg.8]    [Pg.206]    [Pg.234]    [Pg.190]    [Pg.514]    [Pg.106]    [Pg.3555]    [Pg.106]    [Pg.259]    [Pg.161]    [Pg.102]    [Pg.108]    [Pg.221]    [Pg.426]    [Pg.226]    [Pg.214]    [Pg.214]    [Pg.11]    [Pg.54]   
See also in sourсe #XX -- [ Pg.51 , Pg.196 ]




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