Acetylene synthesis

FRITSCH BUTTENBERG - WIECHELL Acetylene Synthesis Alpha elimination from haloethylenes leading via carbene rearrangement to acetylenes... 

S. Yamaguchi and T.M. Swager, Oxidative cyclization of bis(biaryl)acetylenes synthesis and photophysics of dibcnzo, /j]chrysene-based fluorescent polymers, J. Am. Chem. Soc., 123 12087-12088, 2001. 

Bis-acetylene synthesis from alkynyl halides and alkynyl copper reagents. Cf. Castro-Stephens reaction. 

Aryl-acetylene synthesis, Cf. Cadiot-Chodkiewicz coupling and Sonogashira coupling. The Castro-Stephens coupling uses stoichiometric copper, whereas the Sonogashira variant uses catalytic palladium and copper. 

Methane is an important starting material for numerous other chemicals. The most important of these are ammonia, methanol, acetylene, synthesis gas, formaldehyde, chlorinated methanes, and chlorofluorocarbons. Methane is used in the petrochemical industry to produce synthesis gas or syn gas, which is then used as a feedstock in other reactions. Synthesis gas is a mixture of hydrogen and carbon monoxide. It is produced through steam-methane reforming by reacting methane with steam at approximately 900°C in the presence of a metal catalyst CH4 + H20 —> CO + 3H2. Alternately, methane is partially oxidized and the energy from its partial combustion is used to produce syn gas ... 

Sometimes the triethylsilyl grouping is more suitable for poly-acetylene synthesis because of its greater stability, namely in the Cadiot-Chodkiewicz coupling reaction44 of a halogenoacetylene with unprotected l-phenyl-buta-l,3-diyne (39)... 

A combination of the Wittig reaction with an acetylene synthesis was applied by Cochrane and Hanson in the synthesis of JH2 1S0). Subsequently, they used Corey s stereoselective route 1S1) but obtained only 27% (Z)-isomer of the hormone, i.e. a poor stereoselectivity (Scheme 37). 

Several reactions have, however, become of fundamental, theoretical and practical importance for instance, Berthelot s acetylene synthesis, the preparation of carbides, and some other processes. 

Acetylene synthesis is dominated by three major problems associated with its ther-modynamic properties. 

Often, a large quantity of hydrogen chloride is evolved with the formation of monochloroSlefins, RC(Cl) = CHR however, the resulting mixture is suitable for the acetylene synthesis. Small amounts of dichloro compounds of the type RCHCICHCIR are also formed. These side reactions ate limited by adding the ketone to the phosphorus pentachloride at 0° C... 

FRITSCH. BUTTENBERG - W IE C H E L L Acetylene Synthesis Alpha eKimnation from haloethylenes leading via caibene reacrangement to acetylenes... 

FRIEDLANDER Quinoline synthesis t32 FRIES Phenol ester rearrangement 133 FRITSCH. BUTTENBERG - WIECHELL Acetylene synthesis 134... 

Z-tamoxifen 403 tandem cyclization 290, 295 tandem Heck reaction-anion capture 253-4 tandem Heck reaction-phenoxide capture 253 tandem Heck reactions 251, 252-4 tandem intramolecular Heck-intermolecular Stille cross-coupling 255 taxol 140, 143,243,245 ( )-tazettine 146,234 telomerization 352 telomerization products 343, 345 template effect 140 teraconic anhydride 468 terminal acetylenes, synthesis of 216-20 terminal alkynes 6, 213 terminal 2,2-diorgano-l-aIkcnylboronates 51 terminal diynes 207 ternary complex 444 ternary coupling 177... 

Jungheim, L.N., and Sigmund, S.K., 1,3-Dipolar cycloaddition reactions of pyrazolidinium ylides with acetylenes. Synthesis of a new class of antibacterial agents, J. Org. Chem., 52, 4007, 1987. 

Acetylene synthesis (2, 419-422). Wieland1 has extended the fragmentation of << /3-epoxyketones to give acetylenes to a new synthesis of acetylenes by the reaction of a-halo. or a-sulfonyloxy ketones with p-toluenesulfonylhydrazine. Thus reaction of either (la) or (lb) with p-toluenesulfonylhydrazine in the presence of potassium acetate in methylene chloride-acetic acid (4 days) gives the acetylene (2) in 50% yield. 

Acetylene synthesis. 3,4-DiaIkyl-4-halo-2-pyrazoline-5-ones (1) are known to be converted into a, 3-unsaturated carboxylic acids (equation I), with the (El-isomer (2) often predominating. Kocienski et al. reasoned that this stereochemical preference could result from a vinyl radical intermediate (a). Indeed,... 

Acetylene Synthesis by Adding H O to CaC2 (calcium carbide) Sample reaction 17-1... 

Research from our own group in this area resulted in a novel functional group reshuffling reaction by using ruthenium catalyst (eq. 5) and and a palladium catalyzed simple/practical bis(aryl)acetylene synthesis with acetylene gas (eq. 6) (26). 

The route to prepare 1,2,4-butanetriol trinitrate is to adopt the process of acetylene synthesis, as shown in the following equations ... 

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