Acetic acid and acetates

Upon fractionation, the acetic acid and acetic anhydride pass over first, followed by the pure dialkyl-aniline. 

Similar activation takes place in the carbonylation of dimethyl ether to methyl acetate in superacidic solution. Whereas acetic acid and acetates are made nearly exclusively using Wilkinson s rhodium catalyst, a sensitive system necessitating carefully controlled conditions and use of large amounts of the expensive rhodium triphenylphosphine complex, ready superacidic carbonylation of dimethyl ether has significant advantages. 

Tabulating Values for K and Kb A useful observation about acids and bases is that the strength of a base is inversely proportional to the strength of its conjugate acid. Consider, for example, the dissociation reactions of acetic acid and acetate. 

Lavoisier beUeved he could distinguish acetic acid from acetous acid, the hypothetical acid of vinegar, which he thought was converted into acetic acid by oxidation. Following Lavoisier s demise, Adet proved the essential identity of acetic acid and acetous acid, the latter being the monohydrate, and in 1847, Kolbe finally prepared acetic acid from the elements. 

Butane. Butane LPO has been a significant source for the commercial production of acetic acid and acetic anhydride for many years. At various times, plants have operated in the former USSR, Germany, Holland, the United States, and Canada. Only the Hoechst-Celanese Chemical Group, Inc. plants in Pampa, Texas, and Edmonton, Alberta, Canada, continue to operate. The Pampa plant, with a reported aimual production of 250,000 t/yr, represents about 15% of the 1994 installed U.S. capacity (212). Methanol carbonylation is now the dominant process for acetic acid production, but butane LPO in estabhshed plants remains competitive. 

Synthesis Gas Chemicals. Hydrocarbons are used to generate synthesis gas, a mixture of carbon monoxide and hydrogen, for conversion to other chemicals. The primary chemical made from synthesis gas is methanol, though acetic acid and acetic anhydride are also made by this route. Carbon monoxide (qv) is produced by partial oxidation of hydrocarbons or by the catalytic steam reforming of natural gas. About 96% of synthesis gas is made by steam reforming, followed by the water gas shift reaction to give the desired H2 /CO ratio. 

In addition to the conventional mixed acids commonly used to produce DNT, a mixture of NO2 and H2SO4 (8), a mixture of NO2 and oxygen (9), and just HNO (10) can also be used. TerephthaUc acid and certain substituted aromatics are more amenable to nitrations using HNO, as compared to those using mixed acids. For compounds that are easily nitratable, acetic acid and acetic anhydride are sometimes added to nitric acid (qv). Acetyl nitrate, which is a nitrating agent, is produced as an intermediate as follows ... 

The most common oxidatiou states and corresponding electronic configurations of rhodium are +1 which is usually square planar although some five coordinate complexes are known, and +3 (t7 ) which is usually octahedral. Dimeric rhodium carboxylates are +2 (t/) complexes. Compounds iu oxidatiou states —1 to +6 (t5 ) exist. Significant iudustrial appHcatious iuclude rhodium-catalyzed carbouylatiou of methanol to acetic acid and acetic anhydride, and hydroformylation of propene to -butyraldehyde. Enantioselective catalytic reduction has also been demonstrated. 

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). 

Nitration. It is difficult to control nitration of thiophene, which yields 2-nitrothiophene [609-40-9]. The strongly electropbilic nitronium ion leads to significant yields (12—15%) of 3-isomer. A preferred procedure is the slow addition of thiophene to an anhydrous mixture of nitric acid, acetic acid, and acetic anhydride. 

Alternatively, TiCl reacts with a cold mixture of acetic acid and acetic anhydride. If the mixture is heated, condensation occurs with elimination of acetyl chloride to yield hexaacetoxydititanoxane [4861 -18-1] (126,127). 

The first reaction may be carried out either in the liquid or vapour phase although the liquid phase route is now commercially obsolete. In a typical liquid phase preparation, acetylene is passed through an agitated solution of glacial acetic acid and acetic anhydride containing mercuric sulphate, preferably formed in situ, in a finely divided state as catalyst. 

November 14, 1987, three people were killed when two explosions and a tire caused extensive damage to the Hoechst Celanese acetic acid and acetic anhydride plant located near Pampa, ( X. Also on the Pampa site was a specialty resins plant operated by Interez, a unit ol RTZ ( orp. vhieh was interrupted because it depends on power supplied from the main Hoechsi Celanese I pc rati on. 

Ethylene is produced in quantity using acetylene or propylene as feedstock to make a large number of products (Figure 7.2-3) such as acetaldehyde, acrylonitrile, acetic acid, and acetic anhydride. These are made generally from acetylene which is made from calcium carbide. 

Acetaldehyde is a colorless liquid with a pungent odor. It is a reactive compound with no direct use except for the synthesis of other compounds. For example, it is oxidized to acetic acid and acetic anhydride. It is a reactant in the production of 2-ethylhexanol for the synthesis of plasticizers and also in the production of pentaerithritol, a polyhydric compound used in alkyd resins. 

Processing and storage equipment for many chemicals, including acetaldehyde, formaldehyde, nylon salt, methyl methacrylate, carbon tetrachloride, glycerol, triacetin, proprionic acid, acetic acid and acetic anhydride, is manufactured from aluminium alloys, primarily because of their excellent corrosion resistance. 

Similarly, if a small concentration of hydroxide ions be added, the latter will combine with the hydrogen ions arising from the dissociation of the acetic acid and form water the equilibrium will be disturbed, and more acetic acid will dissociate to replace the hydrogen ions removed in this way. In either case, the concentration of the acetic acid and acetate ion (or salt) will not be appreciably changed. It follows from equation (21) that the pH of the solution will not be materially affected. 

V-chloro compounds have also been used for the preparation of sulphones from sulphoxides. /V-chlorosuccinimide(NCS) oxidizes sulphoxides in aqueous acetic acid and acetic acid-perchloric acid mixtures. In purely aqueous media, the reaction is very slow and marked decomposition of the NCS occurs with no oxidation being evident105. 

As one example, dissolving sodium acetate in a solution of acetic acid produces a buffer solution in which both acetic acid and acetate anions are major species. Example describes an acetic acid-acetate buffer solution. 

Notice that the H3 0+ concentration is much smaller than the concentrations of acetic acid and acetate, so the approximation that x is negligibly small is valid. The concentrations of acetic acid and acetate are reasonable, being comparable to the starting concentrations. 

The chemist must prepare a solution that contains acetic acid and acetate in amounts that generate a buffer with... 

This buffer region contains the midpoint of the titration, the point at which the amount of added OH" is equal to exactly half the weak acid originally present. In the current example, the solution at the midpoint contains 0.0375 mol each of acetic acid and acetate. Applying the buffer equation reveals the key feature of the midpoint ... 

This process is carried out on an industrial scale in bubble columns [57]. Acetic acid and acetic anhydride are fed together with a recycle solution composed of acetic acid, acetyl chloride, monochloroacetic acid, dichloroacetic acid and hydrogen chloride. Under these conditions, acetic anhydride and hydrogen chloride give acetyl chloride spontaneously. 

The one-step reaction of H2prCl6] with MeC02Li under 02 in a mixed solvent of acetic acid and acetic anhydride yields the Ir11 binuclear complex [Ir2(/u-02CMe)2Cl2(C0)2].483 Crystal-structure determinations of [Ir2(/x-02CMe)2Cl2(C0)2L2], (295), where L = MeCN, DMSO, and py, are reported. The one-electron oxidation product for (295), L = py, is EPR active at 77 K the odd electron occupies the 6Ir Ir orbital. 

---