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Ketene production from acetic acid

Acrolein and condensable by-products, mainly acrylic acid plus some acetic acid and acetaldehyde, are separated from nitrogen and carbon oxides in a water absorber. However in most industrial plants the product is not isolated for sale, but instead the acrolein-rich effluent is transferred to a second-stage reactor for oxidation to acrylic acid. In fact the volume of acrylic acid production ca. 4.2 Mt/a worldwide) is an order of magnitude larger than that of commercial acrolein. The propylene oxidation has supplanted earlier acrylic acid processes based on other feedstocks, such as the Reppe synthesis from acetylene, the ketene process from acetic acid and formaldehyde, or the hydrolysis of acrylonitrile or of ethylene cyanohydrin (from ethylene oxide). In addition to the (preferred) stepwise process, via acrolein (Equation 30), a... [Pg.53]

The production of acetic anhydride from acetic acid occurs via the intermediate formation of ketene where one mole of acetic acid loses one mole of water ... [Pg.240]

Figure 17.14. Some unusual reactor configurations, (a) Flame reactor for making ethylene and acetylene from liquid hydrocarbons [Patton et al., Pet Refin 37(li) 180, (1958)]. (b) Shallow bed reactor for oxidation of ammonia, using Pt-Rh gauze [Gillespie and Kenson, Chemtech, 625 (Oct. 1971)]. (c) Sdioenherr furnace for fixation of atmospheric nitrogen, (d) Production of acetic acid anhydride from acetic acid and gaseous ketene in a mixing pump, (e) Phillips reactor for low pressure polymerization of ethylene (closed loop tubular reactor), (f) Polymerization of ethylene at high pressure. Figure 17.14. Some unusual reactor configurations, (a) Flame reactor for making ethylene and acetylene from liquid hydrocarbons [Patton et al., Pet Refin 37(li) 180, (1958)]. (b) Shallow bed reactor for oxidation of ammonia, using Pt-Rh gauze [Gillespie and Kenson, Chemtech, 625 (Oct. 1971)]. (c) Sdioenherr furnace for fixation of atmospheric nitrogen, (d) Production of acetic acid anhydride from acetic acid and gaseous ketene in a mixing pump, (e) Phillips reactor for low pressure polymerization of ethylene (closed loop tubular reactor), (f) Polymerization of ethylene at high pressure.
A portion of the acetic acid, which is the major product, can be converted in a separate unit to acetic anhydride. Acetic anhydride may be produced from acetic acid, acetone, or acetaldehyde. With both acetic acid and acetone the initial product is ketene. The ketene is highly reactive and reacts readily... [Pg.384]

Single pulse, shock tube decomposition of acetic acid in argon inv olves the same pair of homogeneous, molecular first-order reactions as thermolysis (19). Platinum on grapliite catalyzes the decomposition at 500—800 K at low pressures (20). Ketene, methane, carbon oxides, and a variety of minor products are obtained. Photochemical decomposition yields methane and carbon dioxide and a number of free radicals, wliich have complicated pathways (21). Electron impact and gamma rays appear to generate these same products (22). Electron cyclotron resonance plasma made from acetic acid deposits a diamond [7782-40-3] film on suitable surfaces (23). The film, having a polycrystalline stmcture, is a useful electrical insulator (24) and widespread industrial exploitation of diamond films appears to be on the horizon (25). [Pg.66]

While acetone would serve as a source of ketene in a number of locations, the acetic acid dehydration would predominate and the acetic acid based ketene process is still widely practiced at the start of the 2r century. While acetone had some attractive features, particularly the generation of an inert co-product (methane) rather than reactive water which can destroy ketene, there are some sound reasons the acetic acid process predominated. First, let s recall that during the period 1910-1920, representing the time these processes were introduced, acetone was still made from calcium acetate, so acetone was obtained, at the time, in a two step process from acetic acid. The choice of acetic acid skipped two steps and eliminated wastes. [Pg.369]

Uses. The lowest member of this class, ketene itself, is a powerful acetylating agent, reacting with compounds containing a labile hydrogen atom to give acetyl derivatives. This reaction is used only when the standard acetylation methods with acetic anhydride or acetyl chloride [75-36-5] do not work weU. Most of the ketene produced worldwide is used in the production of acetic anhydride. Acetic anhydride is prepared from the reaction of ketene and acetic acid. [Pg.476]

Production is by the acetylation of 4-aminophenol. This can be achieved with acetic acid and acetic anhydride at 80°C (191), with acetic acid anhydride in pyridine at 100°C (192), with acetyl chloride and pyridine in toluene at 60°C (193), or by the action of ketene in alcohoHc suspension. 4-Hydroxyacetanihde also may be synthesized directiy from 4-nitrophenol The available reduction—acetylation systems include tin with acetic acid, hydrogenation over Pd—C in acetic anhydride, and hydrogenation over platinum in acetic acid (194,195). Other routes include rearrangement of 4-hydroxyacetophenone hydrazone with sodium nitrite in sulfuric acid and the electrolytic hydroxylation of acetanilide [103-84-4] (196). [Pg.316]

The filtrate from this first batch will comprise a solution of 180 to 270 kg of unprecipitated acetylsalicylic acid (1.0 to 1.5 mols), 510 kg of acetic anhydrice (5.0 mols), 600 kg of acetic acid (10.0 mols) (obtained as a by-product in the acetylation step) and 1,200 kg of the diluent toluene. Into this filtrate, at a temperature of 15° to 25°C, ketene gas is now passed through a sparger tube or diffuser plate, with good agitation, until a weight increase of 420.5 kg of ketene (10 mols) occurs. The reaction mixture wiil now contain 180-270 kg of unprecipitated acetylsalicylic acid (1.0-1.5 mols) and 1,532 kg of acetic anhydride (15 mols) in 1,200 kg of toluene. This mother liquor is recycled to the first step of the process for reaction with another batch of 1,382 kg of salicylic acid. On recirculating the mother liquor, the yield of pure acetylsalicylic acid is 1,780 to 1,795 kg per batch. [Pg.108]

Cycloaddition to alkynes, cyclobutenones. This ketene when formed in situ from CCI3COCI and Zn/Cu, reacts with alkynes to form 4,4-dichlorocyclobuten-ones,3 which can rearrange in part to 2,4-dichlorocyclobutenones.4 Both products are reduced to the same cyclobutenone by Zn(Cu) in HOAc/pyridine (4 1) or by zinc and acetic acid/TMEDA.5... [Pg.129]

Since reaction of wood with acetic anhydride leads to the formation of acetic acid by-product, which must be removed from the wood, there has been some interest in the use of ketene gas for acetylation (Figure 4.4a). Ketene, for reaction with wood, is produced by pyrolysis of diketene. Provided that the wood contains no moisture, no acetic acid by-product is produced. However, ketene presents handling problems it is very toxic and explosive, and it also has a tendency to dimerize. A comprehensive series of studies of ketene-based acetylation has been performed in Latvia and this work has been reviewed by Morozovs etal. (2003). Hardwoods have been found to be more reactive to ketene than softwoods and the optimal temperature for reaction has been determined as 47 °C. Application of vacuum and treatment of wood with ammonia solution has been used to remove the excess ketene. The reaction of wood with liquid diketene was also studied, with a WPG of 35 % being obtained after reaction for 3 hours at 52 °C. [Pg.83]

Acetic anhydride may be produced by three different methods. The first procedure involves the in situ production from acetaldehyde of peracetic acid, which in turn reacts with more acetaldehyde to yield the anhydride. In the preferred process, acetic acid (or acetone) is pyrolyzed to ketene, which reacts with acetic acid to form acetic anhydride. A new process to make acetic anhydride involves CO insertion into methyl acetate. This may be the process of the future. [Pg.223]

The presence of phenol in large amounts among the products shows that it does not result only from the disproportionation of phenyl acetate (scheme 2). Indeed this reaction should lead to equal amounts of phenol and acetoxyacetophenones. Actually the phenol/(acetoxyacetophenone + IV + V) molar ratio is much greater than one (between 30 and 80). This means that phenyl acetate decomposes either into phenol plus acetic acid (which would require moisture) or more likely into phenol plus ketene. [Pg.518]

Cyclization of halogenoaryl-substituted /3-lactams can be mediated by palladium(n) derivatives. The formation of the lactam from a ketene-imine addition and subsequent cyclization of the product can be carried out as a one-pot process. As an example, in situ generation of the ketene from the acid chloride and formation of the /3-lactam followed by addition of palladium(ll) acetate, triphenylphosphine, and thalium carbonate gave 495 in 54% yield (Equation 79) <1995TL9053>. [Pg.304]

One method for the synthesis of hydroxyalkyl-substituted P-lactams is by the Staudinger reaction, the most frequently used method for the synthesis of P-lactams.86 This method for the preparation of 4-acetoxy- and 4-formyl-substituted P-lactams involves the use of diazoketones prepared from amino acids. These diazoketones are precursors for ketenes, in a diastereoselective, photochemically induced reaction to produce exclusively tram-substituted P-lactams. The use of cinnamaldimines 96, considered as vinylogous benzaldimines, resulted in the formation of styryl-substituted P-lactams. Ozonolysis, followed by reductive workup with dimethyl sulfide, led to the formation of the aldehyde 97, whereas addition of trimethyl orthoformate permitted the production of the dimethyl acetal 98 (Scheme 11.26). [Pg.181]

Chiral aryl acetic acids constitute a privileged class of target structures due to their prevalence in bioactive natural products and pharmaceuticals and so, unsurprisingly, they constitute attractive targets for asymmetric synthesis [198]. The face-selective addition of a nucleophile to an aryl alkyl ketene provides a very direct entry for the preparation of such compounds. Although this can be achieved by the use of a chiral nucleophile or acid (cf. Scheme 8.1) [199], catalysis of the addition of an achiral nucleophile is clearly attractive from the standpoint of efficiency. [Pg.321]

The reaction products, shown in Table 1, are mainly those expected to be formed by interaction of vinyl cations with water, reasonably via enol derivatives as indicated in equations (2) and (3). Acetic acid and olefins are also formed from compounds (3) (Y = 0 R = i-Pr, t-Bu) besides the expected carboxylic esters. In these oases, splitting of the vinyl cation formed initially to keten and a carbonium ion following equation (4) (R = t-Bu) takes place to approximately 12% when R = i-Pr and 60% whenR = t-Bu (Stamhuis and Drenth, 1963b). [Pg.191]

As shown in Scheme 78, the transient bicyclo[3.3.0]oxonium ylide 255 that was generated from a THF-substituted diazoketone was first protonated by acetic acid to the corresponding bicyclo[3.3.0]oxonium ion, which then provided the ring expansion product <1996CC1077>. In the presence of the weakly acidic MeOH, the ylide underwent a concerted [3+2] cycloreversion to a ketene intermediate to form the ring cleavage product <2004JOC1331>. [Pg.471]

Some methanol, ketene and hydrogen peroxide (as well as a few other minor products) were also detected, while at 400 °C Hoare and Ting-Man Li [31] found the first of these to be relatively a much more important product. These workers also found acetic acid, but this could have been formed from ketene. [Pg.450]

Acetic acid decomposed on the (114[-faceted of the TiOi (001) surface to produce ketene as well as acetone [44]. The acetone generated arose from bimolecular coupling of pairs of surface acetates at four-fold coordinate cations this is analogous to the production of formaldehyde from surface formate on identically prepared surfaces. The reaction of propionic acid corresponded directly to the reaction of acetic acid, producing methyl ketene and 3-pentanone [46]. [Pg.423]


See other pages where Ketene production from acetic acid is mentioned: [Pg.66]    [Pg.520]    [Pg.573]    [Pg.235]    [Pg.266]    [Pg.246]    [Pg.78]    [Pg.194]    [Pg.172]    [Pg.30]    [Pg.195]    [Pg.63]    [Pg.1542]    [Pg.30]    [Pg.19]    [Pg.391]    [Pg.98]    [Pg.121]    [Pg.63]    [Pg.87]    [Pg.140]    [Pg.75]    [Pg.464]    [Pg.78]    [Pg.886]   
See also in sourсe #XX -- [ Pg.369 ]




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