Hydrogenation, acetic anhydride acetaldehyde

In addition to the successful reductive carbonylation systems utilizing the rhodium or palladium catalysts described above, a nonnoble metal system has been developed (27). When methyl acetate or dimethyl ether was treated with carbon monoxide and hydrogen in the presence of an iodide compound, a trivalent phosphorous or nitrogen promoter, and a nickel-molybdenum or nickel-tungsten catalyst, EDA was formed. The catalytst is generated in the reaction mixture by addition of appropriate metallic complexes, such as 5 1 combination of bis(triphenylphosphine)-nickel dicarbonyl to molybdenum carbonyl. These same catalyst systems have proven effective as a rhodium replacement in methyl acetate carbonylations (28). Though the rates of EDA formation are slower than with the noble metals, the major advantage is the relative inexpense of catalytic materials. Chemistry virtually identical to noble-metal catalysis probably occurs since reaction profiles are very similar by products include acetic anhydride, acetaldehyde, and methane, with ethanol in trace quantities. 

Acetyl chlotide is reduced by vatious organometaUic compounds, eg, LiAlH (18). / fZ-Butyl alcohol lessens the activity of LiAlH to form lithium tti-/-butoxyalumium hydtide [17476-04-9] C22H2gA102Li, which can convert acetyl chlotide to acetaldehyde [75-07-0] (19). Triphenyl tin hydtide also reduces acetyl chlotide (20). Acetyl chlotide in the presence of Pt(II) or Rh(I) complexes, can cleave tetrahydrofuran [109-99-9] C HgO, to form chlorobutyl acetate [13398-04-4] in about 72% yield (21). Although catalytic hydrogenation of acetyl chlotide in the Rosenmund reaction is not very satisfactory, it is catalyticaHy possible to reduce acetic anhydride to ethylidene diacetate [542-10-9] in the presence of acetyl chlotide over palladium complexes (22). Rhodium trichloride, methyl iodide, and ttiphenylphosphine combine into a complex that is active in reducing acetyl chlotide (23). 

In addition to small amounts of methane, acetaldehyde or acetic anhydride can be generated in substantial quantities depending on conditions. However, they are not present simultaneously in any appreciable quantity. Acetic anhydride and acetaldehyde must be competitively formed (equation 6), and subsequently react with each other to form EDA (step C). This reaction (step C) is generally catalyzed by protic acids (2-4). The reaction solution for reductive carbonylation is quite acidic HI is an intermediate generated under reaction conditions of high alkyl iodide concentration and hydrogen pressure. The thermodynamic equilibrium of this condensation is quite favorable for diester formation existence of an abundance of either anhydride or aldehyde in the presence of the other is not found. Yields of stoichiometric preparations are in excess of 95%... 

Hydrogenation of acetic anhydride to acetaldehyde (equation 23) has been demonstrated utilizing cobalt carbonyl under one atmosphere of hydrogen. However, the cobalt complex is short lived. A more efficient cobalt catalyzed reaction with substantial catalyst longevity was realized at a temperature of 190 and 3000 psi pressure CO and hydrogen. The main products were equal amounts of EDA and acetic acid. Upon investigation, this reaction was found exceptionally efficient at a more reasonable 1500 psi pressure provided that the temperature was maintained... 

The hydrogenation of acetic anhydride was also performed in the vapor phase over a supported palladium catalyst resulting in acetaldehyde and acetic acid in high yields (36). To avoid recycling, the reactor was designed for complete reaction of acetic anhydride. Minor selectivity loss was found in formation of ethyl acetate (0.5-1.5%) and methane (0.5%). Typical reaction conditions were 160-200 C, 30-100 psi, with a hydrogen-anhydride ratio of 3 1 to 10 1. A similar catalyst was used in the liquid phase (37). The simplicity and high selectivity of this process is certainly attractive. 

Reactions lla-e add up to Reaction 10. Reactions lla-b have been shown above to be catalyzed by Rh/CH3l. Reaction 11c, i.e. acid-catalysed pyrolysis of EDA to acetaldehyde and acetic anhydride, is well documented (9). Both reaction lid, hydrogenation of aldehyde, and Reaction lie, carbonylation of alcohols, are of course well known. The reaction sequence is in agreement with the fact that EDA and AH, especially in short-duration experiments, are detected as by-products. Acetaldehyde is also observed in small quantities, but no ethanol is found. Possibly, Reactions lid and He occur concertedly. We have separately demonstrated that both EDA and AH are suitable feeds to produce propionic acid under homologation reactions conditions. We thus demonstrated... 

Methanolysis of 9-(l-methoxyethyl)carbazole with methanol-hydrogen chloride gave carbazole and acetaldehyde dimethyl acetal. 9,9 -Di-(3,6-dibromocarbazolyl)methane gave 9-acetyl-3,6-dibromocarbazole with acetic anhydride and a trace of sulfuric add. ... 

Potentially explosive reaction with 5-azidotetrazole, bromine pentafluoride, chromium trioxide, hydrogen peroxide, potassium permanganate, sodium peroxide, and phosphorus trichloride. Potentially violent reactions with acetaldehyde and acetic anhydride. Ignites on contact with... 

A powerful oxidizer. Explosive reaction with acetaldehyde, acetic acid + heat, acetic anhydride + heat, benzaldehyde, benzene, benzylthylaniUne, butyraldehyde, 1,3-dimethylhexahydropyrimidone, diethyl ether, ethylacetate, isopropylacetate, methyl dioxane, pelargonic acid, pentyl acetate, phosphoms + heat, propionaldehyde, and other organic materials or solvents. Forms a friction- and heat-sensitive explosive mixture with potassium hexacyanoferrate. Ignites on contact with alcohols, acetic anhydride + tetrahydronaphthalene, acetone, butanol, chromium(II) sulfide, cyclohexanol, dimethyl formamide, ethanol, ethylene glycol, methanol, 2-propanol, pyridine. Violent reaction with acetic anhydride + 3-methylphenol (above 75°C), acetylene, bromine pentafluoride, glycerol, hexamethylphosphoramide, peroxyformic acid, selenium, sodium amide. Incandescent reaction with alkali metals (e.g., sodium, potassium), ammonia, arsenic, butyric acid (above 100°C), chlorine trifluoride, hydrogen sulfide + heat, sodium + heat, and sulfur. Incompatible with N,N-dimethylformamide. 

The hydrocarbonylation of methyl acetate catalyzed by homogeneous Rh complexes generates 1,1-diacetoxyethane ( ethylidene diacetate ) [61] the formal addition product of acetic anhydride and acetaldehyde. Ethylene diacetate is the predominant by-product of the process. The level of ethylidene diacetate production is directly related to the hydrogen partial pressure in the reactor [62]. 

CH3COOH fHjOj CH3C000H + Hs,0 It may be obtained by mixing together acetic anhydride and 90 per cent hydrogen peroxide in the presence of a catalyst such as 1 per cent of sulphuric acid. It is now manufactured by the oxidation of acetaldehyde... 

Acetic anhydride is formed by Rh catalyzed carbonyiation of methyl acetate followed by hydrogenation via the cobalt catalyst to acetaldehyde and acetic acid. The selectivity to acetaldehyde is 85%. Ethylidene diacetate is a by-product resulting from the reaction of acetaldehyde with acetic anhydride. 

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