Butynediol synthesis

Schoenemann88 examined the liquid holdup in trickle-bed reactors used for butynediol synthesis. The data were obtained in a technical reactor 16 m high and 0.8 m in diameter and in a pilot-scale reactor 3.5 m high and 32 mm in diameter. Cylindrical silica catalyst pellets of 4 mm diameter were investigated. The results showed that the liqu jd holdup was, independent, fifboth the gas and i quid fl w rates tir the range of-2-thr ugh--V -fn h- - ) and was-influenced bv... 

Kale SS, Chaudhari RV, Ramachandran PA. Butynediol synthesis. A kinetic study. Ind. Eng. Chem. Prod. Res. Dev. 1981 20 309-315. 

The synthesis of dihydrofurans from propargyl esters is another reaction in which both gold and silver have been employed. In early work, Shigemasa et al.37 reported the efficient chirality transfer in the cycloisomerization of monoesters of butynediols. They used 8-15 mol% of AgBF4 as catalyst in benzene at 80°C in the dark. 

In the presence of copper acetylide complexes, the reaction of aldehydes with acetylene and secondary amines (eq. (2)) leads to propargylamines [6]. In contrast to the synthesis of butynediol, this reaction is catalyzed homogeneously. 

The developed procedures were used for the synthesis of Pd catalysts for cyclopentadiene and 1,4-butynediol hydrogenation in the liquid phase. 

Synthesis of butynediol from acetylene and formaldehyde reactor height 18 m, diameter 1.5 m, 100 °C, 3 bar, copper acetyhde catalyst, introduction of cold acetylene at various points in the reactor. 

The reaction between formaldehyde and acetylene is exothermic M = -100 kJ/mol) and the control of temperature is critical. To solve this problem it has been chosen to limit the temperature increase by injecting cold acetylen at different levels in the bed (T) This arrangement with the flowsheet of the Reppe s synthesis of butynediol is shown on Figure Propargyl alcohol is formed according to the following equation ... 

The second step of this butadiene synthesis, the hydrogenation of butynediol, can also use trickle-bed reactors. This will be described below. 

Three reaction systems of industrial importance, i.e. Fischer-Tropsch synthesis (FTS) and the methema-tion of CO in batch slurries of molten wax and the continuous hydrogenation of butynediol, were used which obey first, half and second order rate laws, respectively. Kinetic expressions, rate constants and the reaction conditions are given in Tedjle 1. 

In 2006, Gagosz and coworkers developed a stereoselective synthesis of functionalized dihydrofurans from butynediol monobenzoates (eqs 6 and 7) using 1 as catalyst. This reaction also employed an initial Au-catalyzed 3,3-rearrangement of propargylic carboxylates, followed by intramolecular stereos-... 

In 2006, Gagosz reported the gold-mediated stereoselective synthesis of 2,5-dihydrofurans from butynediol monobenzoates at room temperature. The transformation involved two sequential gold-catalysed reactions the formation of an allene derivative followed by a cyclisation. The reaction was... 

In contrast, the reverse of the sulphoxide-sulphenate ester rearrangement forms the basis for the synthesis of the dienes (261) and (262) and the enamine (263). The diene (261) is obtained via two consecutive 2,3-sigmatropic rearrangements when the butynediol (264 X = H) is treated with PhSCl-NEta, whereas diene (262) is formed after one 2,3-rearrangement from the mono-acetylated butynediol (264 X = Ac). When the same reagent combination is used with the propargyl alcohols (265) a similar 2,3-rearrangement occurs and... 

The use of solid-liquid phase transfer catalysis in the conjunction with bis(carbonylimidazolides) (i) bis(p-nitrophenylcarbonates) 10) as developed by Fre-chet for the synthesis of novel tertiary copolycarbonates. The instability of tertiary chloroformates renders tertiary polycarbonates inaccessible through conventional chloroformate monomers or intermediates. The bis(carbonylmiidazoiide) monomer was shown to polymerize with both tertiary (3) and secondary alcohols (lljy demonstrating the utility of the method in forming polycarbonates fi-om less reactive steri-cally hindered monomers. Most of the examples reported involved benzene dimethanol derivatives, or 1,4-butynediol, indicating that an adjacent site of unsaturation may activate the alcohol in the solid-liquid phase transfer reaction scheme. 

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