Methanol methyl acetate mixture

As an example. Van Dongen (Ph.D. Thesis, University of Massachusetts, 1983) considered the separation of a methanol-methyl acetate mixture, which forms a homogeneous azeotrope, using n-hexane as an entrainer. The distillation boundaries for this system (Fig. 13-87a) are somewhat curved. A separation sequence that exploits this boundary curvature is shown in Fig. 13-87b. Recycled methanol—methyl acetate binary azeotrope and methanol-methyl acetate—hexane ternary azeotrope are added to the original feed FO to produce a net feed com-... 

The concept of co-carbonylation of methanol/methyl acetate mixtures was first introduced by BASF in the early 1950s, but the reaction chemistry was not fully developed to commercial realization [75]. Not until the mid-1980s, after the development of carbonylation processes to produce acetic acid and acetic anhydride, were co-carbonylation processes patented using homogeneous rhodium/iodine catalyst systems (Table 2) [2, 56]. The basic process concept is to manufacture acetic acid and acetic anhydride from methanol and carbon monoxide as the only raw materials and to generate methyl acetate within the process. Similiarly, the suitability of dimethyl ether as a raw material for the generation of the anhydride equivalent in addition to or as a substitute for methyl acetate was revealed by Hoechst [76]. To produce a small fraction of acetic acid besides acetic anhydride as the main product, the carbonylation of methyl acetate could be conducted with small amounts of water or methanol. This variant, first demonstrated by Hoechst [56], is practiced by Eastman Kodak [2]. 

Surprisingly, there is limited nonproprietary experimental data on methanol esterification with acetic acid (29). Studies have been confined to liquid-phase systems distant from equilibrium (30), in regions where hydrolysis is unimportant. A physical study of the ternary methanol—methyl acetate—water system is useful for design work (31). Methyl acetate and methanol form an azeotrope which boils at 53.8°C and contains 18.7% alcohol An apparent methanol—water azeotrope exists, boiling at 64.4°C and containing about 2.9% water. These azeotropes seriously complicate methyl acetate recovery. Methyl acetate is quite soluble in water, and very soluble in water—methanol mixtures, hence two liquid phases suitable for decanting are seldom found. 

Pervaporation of methanol-methyl acetate binary mixtures... 

Sain S, Dinner S, and Savascyi OT. Pervaporation of methanol-methyl acetate binary mixtures. Chem. Engg. Proc. 1998 37(2) 203-206. 

Penkova, A. V., Polotskaya, G. A., Toikka, A. M. (2013). Separation of acetic acid-methanol-methyl acetate-water reactive mixture. Chemical Engineering Science, 101, 586—592. 

Solvent Recovery. A mixture of methanol and methyl acetate is obtained after saponification. The methyl acetate can be sold as a solvent or converted back into acetic acid and methanol using a cationic-exchange resin such as a cross-linked styrene—sulfonic acid gel (273—276). The methyl acetate and methanol mixture is separated by extractive distillation using water or ethylene glycol (277—281). Water is preferred if the methyl acetate is to be hydroly2ed to acetic acid. The resulting acetic acid solution is concentrated by extraction or a2eotropic distillation. 

Chloro-1 -methyl-5-phenyl-s-trizolo[4,3-a]quinoline A stirred mixture of 6triethyl-orthoacetate (0.925 g,0.0057 mol) and xylene (100 ml) was refluxed, under nitrogen, for 2 hours 40 minutes. During this period the ethanol formed in the reaction was removed by distillation through a short,glass helix-packed column. The mixture was concentrated to dryness In vacuo and the residue was crystallized from methanol-ethyl acetate to give 1.28 g of 7-chloro-1-methyl-5-phenyl-s-triazolo[4,3-a]-quinoline (83.9% yield). The analytical sample was crystallized from methylene chloride methanol and had a melting point 252.5°-253.5°C. 

Fig. 5.5.3 ]H NMR spectrum obtained from a sample containing catalyst and reaction mixture (i.e., methanol, acetic acid, methyl acetate and water). Peaks A and B are the intra- and inter-particle ]H resonances, respectively, associated with the OH group. Peak C is the ]H resonance of the CH30 group associated with...

All solvents used for general applications were of reagent grade. For special purposes, purification of solvents was effected using standard procedures. All other reagents were used as supplied commercially except as noted. A solution of chloromethyl methyl ether (6 mmole/mL) in methyl acetate was prepared by adding acetyl chloride (141.2 g, 1.96 mol) to a mixture of dimethoxy methane (180 mL, 2.02 mol) and anhydrous methanol (5.0 mL, 0.12 mol).20 The solution was diluted with 300 mL of 1,1,2,2-tetrachloroethane and used as a stock solution for the chloromethylation experiments. 

Several of the lower molecular weight aliphatic compounds, in a mixture, are part of the roasted coffee aroma. A nine-compound mixture with roasted coffee aroma contained isopentane, n-hexane, acetaldehyde, dimethyl sulfide, propanal, isobutanal, isopentanal, methanol, and 2-methylfuran.20 In addition, the freshness of aroma and taste has been correlated with 2-methylpropanal and diacetyl. When the concentration of these falls off, so does the taste.21 Other aliphatic compounds that are steadily lost from ground roasted coffee, unless it is vacuum packaged, include methyl formate, methyl acetate, methyl thioacetate, and acetone.22 The concentrations in roast coffee for four compounds whose contribution to the fresh flavor have long been known are dimethyl sulfide (4 ppm), methyl formate (12 ppm), isobutanal (20 ppm), and diacetyl (40 ppm). The taste thresholds are 0.1, 0.5, 0.5, and 1.0 ppm, respectively, in the brew made with 5 g coffee per 100 ml water.15... 

Carbomethoxytropinone. A mixture of 1.35 g of sodium methoxide (this is sodium in a minimum amount of methanol), 3.5 g of tropinone, 4 ml of dimethylcarbonate and 10 ml of toluene is refluxed for 30 min. Cool to 0° and add 15 ml of water that contains 2.5 g of ammonium chloride. Extract the solution after shaking with four 50 ml portions of chloroform, dry, evaporate the chloroform in vacuo. Dissolve the oil residue in 100 ml of ether, wash twice with a mixture of 6 ml of saturated potassium carbonate and three ml of 3 N KOH. Dry and evaporate in vacuo to recover the unreacted tropinone. Take up the oil in a solution of aqueous ammonium chloride and extract with chloroform, dry, and evaporate in vacuo to get an oil. The oil is dissolved in hot acetone, cool, and scratch inside of flask with glass rod to precipitate 2-carbomethoxytropinone. Recrystallize 16 g of this product in 30 ml of hot methyl acetate and add 4 ml of cold water and 4 ml of acetone. Put in freezer for 2 /2 to 3 hours. Filter and wash the precipitate with cold methyl acetate to get pure product. 

In anhydrous mixtures, the rhodium catalyzed carbonylation is enhanced by the presence of hydrogen. Introduction of hydrogen to a rhodium catalyzed carbonylation of methyl acetate increases the reaction rate and maintains catalyst stability (26) when the hydrogen partial pressure is rather low. It leads to reduced products formation, e.g. acetaldehyde and ethylidene diacetat with higher hydrogen partial pressure, in excess of 50 psi (27, 28). This is a clear indication that hydrogen is added to the coordination sphere of the rhodium catalyst. However, in the case of methanol carbonylation, the presence of hydrogen does not enhance the reaction rate or lead... 

For example, the reaction of methyl acetate and synthesis gas at 170 C and 5000 psig with a Co-Lil-NPh catalyst results in the formation of acetaldehyde and acetic acid. The rate of acetaldehyde formation is 4.5 M/hr, and the yield based on Equation 15 is nearly 100%. Methane (1-2%) and ethyl acetate (1-2%) are the only by-products. The product mixture does not contain water, methanol or 1,1-dimethoxyethane. The acetic acid can easily be recycled by esterification with methanol in a separate step. 

The carbonylation-homologation reaction may also be carried out on a mixture of alcohols and their formates. For instance, at a very high conversion of the reagents, methanol-methyl formate and i-butaiol -i-butyl formate produce a mixture of oxygenates particularly rich in acetates that are useful as octane improvers for gasoline (Fig. 3). 

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