Acetic acid stage

In vitro, all of the species of the genus Acetobacter oxidize D- and L-lactic acid. Certain strains completely oxidize it into CO2 and H2O, but most stop at the acetic acid stage. The two isomers are transformed, but the activity is exerted more effectively on the D isomer. Pyruvate is the first intermediary. It is first decarboxylated into ethanal, which is oxidized into acetic acid by the ALDH. 

A sandstone to be treated can be high in iron compounds such as siderite (iron carbonate), pyrite (iron sulfide), iron oxides, and iron chlorite clay. If this is the case, a separate acetic acid stage may be needed to reduce iron precipitation potential. The recommended acetic acid volume is 20-100 gal/ ft. Acetic acid reacts with carbonates and reduces reprecipitation of dissolved iron compounds through complexation. 

Homogeneous catalysts. With a homogeneous catalyst, the reaction proceeds entirely in the vapor or liquid phase. The catalyst may modify the reaction mechanism by participation in the reaction but is regenerated in a subsequent step. The catalyst is then free to promote further reaction. An example of such a homogeneous catalytic reaction is the production of acetic anhydride. In the first stage of the process, acetic acid is pyrolyzed to ketene in the gas phase at TOO C ... 

Isoprenoid compounds are biosynthesized from acetate by a process that involves sev eral stages The first stage is the formation of mevalonic acid from three molecules of acetic acid... 

The precipitated cellulose acetate is filtered from the dilute (25—36%) acetic acid. The acetic acid and salts remaining from the sulfuric acid neutrali2ation are removed by washing. The wet polymer is typically dried to a moisture content of 1—5%. The dilute acetic acid obtained from the washing and precipitation steps caimot be used in other stages of the process. Its efficient recovery and recycle are an economic necessity. 

With these kinetic data and a knowledge of the reactor configuration, the development of a computer simulation model of the esterification reaction is iavaluable for optimising esterification reaction operation (25—28). However, all esterification reactions do not necessarily permit straightforward mathematical treatment. In a study of the esterification of 2,3-butanediol and acetic acid usiag sulfuric acid catalyst, it was found that the reaction occurs through two pairs of consecutive reversible reactions of approximately equal speeds. These reactions do not conform to any simple first-, second-, or third-order equation, even ia the early stages (29). 

For the system water-acetic acid-MIBK in Fig. 15-11 the raffinate (water) layer is the solubility curve with low concentrations of MIBK, and the extract (MIBK) layer is the solubihty curve with high concentrations of MIBK. The dashed lines are tie lines which connect the two layers in equihbrium as given in Table 15-1. Example 2 describes the right-triangular method of calculating the number of theoretical stages required. 

Example 2 Stage and Composition Calculation A 100-kg/h feed stream containing 20 weight percent acetic acid in water is to he extracted with 200 kg/h of recycle MIBK that contains 0.1 percent acetic acid and 0.01 percent water. The aqueous raffinate is to he extracted down to 1 percent acetic acid. How many theoretical stages wiU he required and what will the extract composition he ... 

Typical data for operation with methyl isobutyl ketone, water, acetic acid four stages 101.6-mm stage height, 152-mm-diameter column extraction, water ketone. 

Coutor (U.S. Patent 2,036,924, 1936). See also Eisenlohr [Ind. Chem., 27, 271 (1951) Chem. Jng. Tech., 23, 12 (1951) Phorm. Ind., 17, 207 (1955) Trans. Indian Inst. Chem. Eng., 3, 7 (1949-1950)] and Husain et al. [Chim. Ind. ( 4ilan), 82, 435 (1959)]. This centrifuge revolves about a vertical axis and contains three actual stages. It operates at 3800 r/min and handles approximately 4.92 mVh (1300 gaPh) total liquid flow at 12-kW power requirement. Provision is made in the machine for the accumulation of solids separated from the hquids, for periodic removal. It is used, more extensively in Europe than in the United States, for the extraction of acetic acid, pharmaceuticals, and similar produces. 

A one-stage process for producing vinyl acetate directly from ethylene has also been disclosed. In this process ethylene is passed through a substantially anhydrous suspension or solution of acetic acid containing cupric chloride and copper or sodium acetate together with a palladium catalyst to yield vinyl acetate. 

Because of the insolubility of cellulose it is not possible to carry out uniform esterification with the lower organic acids (acetic acid, propionic acid etc.) and in those cases where incompletely substituted derivatives are required a two-stage reaction is employed. This involves total esterification in a medium in... 

Ammodendrine, C jH oONj, HjO (No. 1, table, p. 116). The base has m.p. 73 °, becomes anhydrous at 70-80°, and then melts at 50-60°, Wd i 0°. The salts are amorphous and deliquescent except the hydriodide B. HI, which forms a crystalline precipitate, m.p. 218-20°, from alcohol, and the perchlorate, m.p. 199-200°. An amorphous A-benzoyl derivative was obtained. With methyl iodide ammodendrine behaves as a secondary base, yielding first A-methylammodendrine hydriodide (a crystalline precipitate, m.p. 183-5°, from a mixture of alcohol and acetone), and at the second stage iV-methylammodendrine methiodide, m.p. 163-5°. On hydrogenation ammodendrine furnishes a dihydro-base, which is hydrolysed into acetic acid and 2 3 -dipiperidyl, C oHjoNj, and must be dZ-A-acetyl-3-a-piperidylpiperidine. Ammodendrine should therefore be acetyltetrahydroanabasine and is of biological interest as the first recorded occurrence of this type of alkaloid in the Leguminoss. ... 

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