Reppe process

Ethyne is the starting point for the manufacture of a wide range of chemicals, amongst which the most important are acrylonitrile, vinyl chloride, vinyl acetate, ethanal, ethanoic acid, tri- and perchloro-ethylene, neoprene and polyvinyl alcohol. Processes such as vinylation, ethinylation, carbonylation, oligomerization and Reppe processes offer the possibility of producing various organic chemicals cheaply. Used in oxy-acetylene welding. 

The modified Reppe process was installed by Rohm and Haas at thek Houston plant in 1948 and later expanded to a capacity of about 182 X 10 kg/yr. Rohm and Haas started up a propylene oxidation plant at the Houston site in late 1976. The combination of attractive economics and improved product purity from the propylene route led to a shutdown of the acetylene-based route within a year. 

There are currentiy two principal processes used for the manufacture of monomeric acryhc esters the semicatalytic Reppe process and the propylene oxidation process. The newer propylene oxidation process is preferred because of economy and safety. In this process acroleia [107-02-8] is first formed by the catalytic oxidation of propylene vapor at high temperature ia the preseace of steam. The acroleia is thea oxidi2ed to acryhc acid [79-10-7]. 

Diol Components. Ethylene glycol (ethane 1,2-diol) is made from ethylene by direct air oxidation to ethylene oxide and ring opening with water to give 1,2-diol (40) (see Glycols). Butane-1,4-diol is stiU made by the Reppe process acetylene reacts with formaldehyde in the presence of catalyst to give 2-butyne-l,4-diol which is hydrogenated to butanediol (see Acetylene-DERIVED chemicals). The ethynylation step depends on a special cuprous... 

Garboxylation Reaction. The carboxylation reaction represents the conversion of acetylene and olefins into carboxyHc acids (qv) or their derivatives. The industrially important Reppe process is used in the synthesis of P-unsaturated esters from acetylene. Nickel carbonyl is the catalyst of choice (134). 

The Reppe process for manufacture of acrylic esters uses acetylene and carbon monoxide, with a nickel carbonyl catalyst having high acute and longterm toxicity, to react with an alcohol to make the corresponding acrylic ester ... 

In another Reppe process, acetylene is reacted with formaldehyde to yield butyndiol, which can be converted to butadiene for the manufacture of the synthetic rubber Buna the catalyst is nickel cyanide ... 

Reppe polymerization of acetylene, 17 113 Reppe process, 1 355-357 16 73 Repressor proteins, 20 832 Reprocessing... 

Butanediol is commercially produced by several different processes [7], The most prevalent process for making BDO is known as the Reppe process. This process uses acetylene, generated from natural gas, as its primary feedstock, according to the following ... 

The most recent entrant-to the. club of commodity chemicals is 1,4-butanediol (BDO), a petrochemical used in some of the more specialized applications such as chemical intermediates for the production of tetrahydro-furane and gama-butyrolactone, polybutylene terephthalate, and the more familiar polyurethanes. Traditionally, the Reppe process was the primary route to BDO, based bn acetylene and formaldehyde feeds. More recently, the share of BDO from butane and propylene oxide based production has grown rapidly. 

In-the Reppe process, formaldehyde and acetylene are reacted in.the presence of a.copper acetylide catalyst to give 2-butyne-l,4-diol. That compound is then hydrogenated to give BDO. 

Acetylene is a tricky chemical feedstock. It is extremely reactive (and explosive) and impractical to transport. Generally, the industrial processes that use acetylene are close to the acetylene-generating source. Despite all the drawbacks, the Reppe process was for a half century the preferred process for EDO, but now the growth in EDO is being taken by the propylene oxide (PO) and butane feedstock routes. 

The Reppe process was commercialized in the 1950s. It involves the reaction pf acetylene, carbon monoxide, and an alcohol (methyl, ethyl, etc.) to give an acrylic ester (an acrylate). The process is carried out at 125°F and 15—30 psi in a nickel carbonyl/aqueous hydrochloric acid solution. The nickel carbonyl acts as both a catalyst and a secondary source of carbon monoxide. 

Reppe process yields are about 80%, but the usual acetylene drawbacks are present hazardous materials handling and higher-cost raw materials. As a result the acetylene route plants are not being duplicated as they wear out, giving way to the newer technologies. 

Some acrylates are still produced by a modified Reppe process that involves the reaction of acetylene, the appropriate alcohol (in the case of butyl acrylate, butyl alcohol is used), and carbon monoxide in the presence of an acid. The process is continuous and a small amount of acrylates is made this way. The most economical method of acrylate production is that of the direct oxidation of propylene to acrylic acid, followed by esterification. 

This Reppe process using acetylene for 1,4 butanediol is currently being replaced with processes that start with propylene oxide (C3H60), butadiene (C4H(.), or butane (C4H10). 

The industrial catalytic Reppe process is usually applied in the production of acrylic acid. The catalyst is NiBr2 promoted by copper halides used under forcing conditions. The BASF process, for example, is operated at 225°C and 100 atm in tetrahydrofuran solvent.188 Careful control of reaction conditions is required to avoid the formation of propionic acid, the main byproduct, which is difficult to separate. Small amounts of acetaldehyde are also formed. Acrylates can be produced by the stoichiometric process [Eq. (7.20)], which is run under milder conditions (30-50°C, 1-7 atm). The byproduct NiCl2 is recycled ... 

Reppe process - [NICKELCOMPOUNDS] (Vol 17) -butanediol om [ACETYLENE-DERIVED CHEMICALS] (Vol 1) -use of metal carbonyls [CARBONYLS] (Vol 5)... 

There are currently two principal processes used for the manufacture of monomeric acrylic esters the semicatalytic Reppe process and the propylene oxidation process. The newer propylene oxidation process is preferred because of economy and safety. 

REPPE PROCESS. Any of several processes involving reaction of acetylene (1) with formaldehyde to produce 2-butync-l,4-diol which can be converted to butadiene (2) with formaldehyde under different conditions to produce propargyl alcohol and, form this, allyl alcohol (3) with hydrogen cyanide to yield acrylonitrile (4) with alcohols to give vinyl ethers (5) with amines or phenols to give vinyl derivatives (6) with carbon monoxide and alcohols to give esters of acrylic acid (7) by polymerization to produce cyclooctatetraene and (8) with phenols to make resins. The use of catalysis, pressures up to 30 atm, and special techniques to avoid or contain explosions are important factors in these processes. 

We saw the cis-selective reduction when we made compound 30 in chapter 12 the starting material m-butenediol 18 is readily available as it is made by the Reppe process.3 There is a fascinating story of the reluctant Reppe not divulging the details to the allies after the second world war.4... 

Butanediol is manufactured by way of hydrogenation of butynediol (the Reppe process) ... 

Butadiene (bpi.oi3= —4.413 C, 44 =0.6211) has become a major petrochemical product thanks to the development of its copolymers with styrene and acrylonitrDe. The earliest processes for manufacturing butadim started with acetylene and formaldehyde (Germany, the Reppe process), or produced it by the alUnited States Unwn Carbide). 

Other mechanisms for the Reppe process have been considered. One of the first involved the intermediacy of cyclobutadienes This process has already been discussed in this chapter. It would appear most unlikely from theoretical principles as well as experimental evidence 25,36), Jiie general mechanistic aspects of acetylene oligomerization have been thoroughly reviewed elsewhere S ). 

Povidone is manufactured by the Reppe process. Acetylene and formaldehyde are reacted in the presence of a highly active copper acetylide catalyst to form butynediol, which is hydrogenated to butanediol and then cyclodehydrogenated to form butyrolactone. Pyrrolidone is produced by reacting butyrolac-tone with ammonia. This is followed by a vinylation reaction in which pyrrolidone and acetylene are reacted under pressure. The monomer, vinylpyrrolidone, is then polymerized in the presence of a combination of catalysts to produce povidone. 

Pyrrolidone is prepared from butyrolactone by a Reppe process, in which acetylene is reacted with formaldehyde. 

The applied nickel catalyst, promoted by copper halides, required rather severe reaction conditions T = 220 °C, F = 10 MPa), but gave good AA yields up to 90% based on acetylene. This so-called catalytic Reppe process was commercially operated in Germany, the USA, and Japan. Due to the limited availability of cheap acetylene as feedstock and the severe reaction conditions involved in the carbonylation process, this process has lost the competition with (heterogeneously catalyzed) oxidation of readily available propene, even though a perfect selectivity to AA is not achieved in the latter process. 

In recent years, attention has been focused on alkyne carbonylation catalysts based on the metals nickel, palladium, and platinum, modified with a variety of tertiary (bi)phosphines [5]. TTie main goal has been to develop chemo- and regio-selective carbonylation catalysts for application to higher alkyne substrates for the synthesis of certain fine chemicals. Many of these catalysts do allow the carbonylation to proceed under milder conditions than those applied in the catalytic Reppe process, and some of these catalysts do provide the branched regioisomer product from higher alkynes with good selectivity. However, in all cases reaction rates are very low, i.e., below 100 (and in most cases even below 10) mol/mol metal per h, as are the product yields in mol/mol metal (< 100). These catalyst productivities are far too low for large-scale industrial application in the production of commodity-type products, such as (meth)acrylates. 

Substitution of an hazardous chemical is often an even more complex problem, in particular regarding the trade-off between inherently safer design and sustainable chemistry. Several examples are discussed in subsequent chapters. We thus limit our discussion here to a few aspects. Up until around the 1960s the Reppe process was employed for of synthesis of acrylic esters ... 

Control of reactivity by catalysis provides the capability to shift to lower cost feedstocks. In the twentieth century, advances in catalysis have allowed the substitution of acetylene with olefins and subsequently with synthesis gas as primary feedstocks. For example, production of acrylic acid, traditionally produced by the Reppe process from acetylene and CO, has now been replaced by catalytic oxidation of propylene. The emergence of paraffins, the hydrocarbon feedstock of the future, will depend on development of catalysts for selective alkane C-H activation (2). 

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