Methanol reactions atmosphere

Chemat and his collaborators [92] reported the UV- and MW-induced rearrangement of 2-benzoyloxyacetophenone, in the presence of bentonite, into l-(o-hydroxy-phenyl)-3-phenylpropane-l,3-dione in methanol at atmospheric pressure (Sch. 14.2). The reaction, performed in the reactor shown in Fig. 14.7, was subject to a significant activation effect under simultaneous UV and MW irradiation this corresponded at least to the sum of the individual effects (Fig. 14.11). The rearrangement, however, was not studied in further detail. Such competitive processes can be described by the diagram in Fig. 14.9, because the product obtained from both types of activation was the same. 

The photosensitized oxidation of either trans-2-butene or a mixture of cis- and frans-2-butene in methanol using methylene blue as a sensitizer produced a single hydroperoxide—3-butene-2-hydroperoxide— cleanly at atmospheric pressure. The hydroperoxide was reduced to 3-butene-2-ol by treating the methanolic reaction solution with sodium... 

Chlorofluoroearbons function as chemical intermediates, provided they are consumed rather than released into the atmosphere. CFC-113 serves as the starting material for the production of CTFE monomer. Despite the many years of research into a catalytic vapor-phase process for this conversion, the preferred current method still involves zinc dechlorination in methanol [reaction... 

Another variable is the reaction solvent. Oxygen solubility depends on the solvent used in an oxidation reaction. For example, at 0°C the concentration of oxygen in methanol at atmospheric pressure is 11 times the concentration of oxygen in water. As the temperature is increased to 40 °C, the oxygen solubility in methanol is 21 times greater than that in water. This variable needs to be evaluated during mechanistic studies. 

The nature of the outer-layer of the Cu-Zn based catalysts and the role of the different active sites are still a topic of investigation. Metallic copper is implicated as being the dominant oxidation state of the metal during the reaction. However, the presence of Cu+ is also important as a small amount of oxygen increases the reaction rate.51,66 Shen et al.67 found on ceria supported copper catalyst that in spite of the reductive reaction atmosphere, metallic copper particles on cerium oxide were oxidised during reaction and the catalyst was activated. The formation of the copper oxide species was considered indispensable for the onset of high catalytic activity. Synergy between Cu and ZnO in the catalysis of methanol synthesis... 

Since methanol is a direct reaction product of hydrogen and carbon monoxide, it is theoretically possible by using an excess of carbon monoxide in the original water gas mixture to form first methanol and then acetic acid or ester in one operation. With this end in view, catalysts composed of metals or their compounds, i.e. of nickel, chromium, cobalt, copper, cadmium, or manganese, have been patented.1"4 Catalysts similar to those proposed for the carbon monoxide-methanol reaction and comprising the oxides of copper, tin, lead, the acetate of copper, or tire methylates of aluminum or tin, or mixtures have been claimed for the same reaction at pressures of 150 to 200 atmospheres and at about 300° C.1 4e... 

MTBE synthesis from /-butanol and methanol in a membrane reactor has been reported by Salomon et al. [2.453]. Hydrophilic zeolite membranes (mordenite or NaA) were employed to selectively remove water from the reaction atmosphere during the gas-phase synthesis of MTBE. This reaction was carried out over a bed of Amberlyst 15 catalyst packed in the inside of a zeolite tubular membrane. Prior to reaction, the zeolite membranes were characterized by measuring their performance in the separation of the equilibrium mixture containing water, methanol, /-butanol, MTBE, and isobutene. The results obtained with zeolite membrane reactors were compared with those of a fixed-bed reactor (FBR) under the same operating conditions. MTBE yields obtained with the PBMR at 334 K reached 67.6 %, under conditions, where the equilibrium value without product removal (FBR) would be 60.9%. 

Subsequently, the surface compoimd may give either dimethyl ether or ethylene and water. We have shown that the conversion of methanol at atmospheric pressure and 400°C in contact with silica-alumina, silica gel, and aluminum oxide proceeds in exactly the same manner as it does during the pumping off of chemically adsorbed methanol into a vacuum the composition of the gaseous products is identical in both cases. The gas composition shows that the principal reactions are dehydration and hydrogen transfer. This process at atmospheric pressure proceeds more easily for alumina gel and silica-alumina than for silica gel. 

Nitrobiphenyl gave 2-aminobiphenyl, but no carbazole therefore a nitrene intermediate appeared unlikely in this reduction. The reaction between Kj[HFe(CO)43 and aromatic nitro compounds proceeds vigorously and exothermally in alcohol at room temperature to give the corresponding aromatic amines in excellent yields[76j. The reaction is not catalytic and is not affected by reaction atmospherearomatic nitro compounds with Fe3methanol-benzene is catalysed by the crown ether, 18 crown-6, with aqueous K0H[77j, or by PhCH2N3+Cl " with aqueous NaOH[64,78l. 

If the oil is of acceptable quality, the oil may be taken directly to the transesterification reactor where it is contacted with an excess of the chosen alcohol (usually methanol) and a base catalyst (usually NaOH or KOH). The transesterification reaction is conducted at about 60°C, which is a constraint set by the boiling point of methanol at atmospheric pressure. The oil is immiscible with the shorter-chain alcohols therefore, maintaining intimate contact between the two phases by providing adequate mixing is an important design and operating criterion for the reactor. It is also an important energy input that must be accounted for. 

All of this careful addition is to keep the reaction from starting before the bomb is sealed. It is also important to note that the chemist must scale up or scale down the amount of reactants so that the total amount of all the ingredients consumes no less than 90 of the volume space of her particular pipe bomb. Too much head space with its atmospheric air will lower the yield. The bomb is heated in an oil bath or oven at 105-115°C for 18-24 hours and the contents are then distilled with the 1,3 benzodioxole coming over at about 170-175°C with no vacuum, Alternatively, the chemist can only distill off the methanol, wash with dilute NaOH solution and extract with ether, etc. 

Tandem cyclization and 3-carboxylation has been done with o-(methanesulf-onamido)phenylacetylenes by conducting the reaction in methanol under a CO atmosphere[10]. 

Alcoholysis (ester interchange) is performed at atmospheric pressure near the boiling point of methanol in carbon steel equipment. Sodium methoxide [124-41 -4] CH ONa, the catalyst, can be prepared in the same reactor by reaction of methanol and metallic sodium, or it can be purchased in methanol solution. Usage is approximately 0.3—1.0 wt % of the triglyceride. 

Silver Catalyst Process. In early formaldehyde plants methanol was oxidized over a copper catalyst, but this has been almost completely replaced with silver (75). The silver-catalyzed reactions occur at essentially atmospheric pressure and 600 to 650°C (76) and can be represented by two simultaneous reactions ... 

In contrast to the silver process, all of the formaldehyde is made by the exothermic reaction (eq. 23) at essentially atmospheric pressure and at 300—400°C. By proper temperature control, a methanol conversion greater than 99% can be maintained. By-products are carbon monoxide and dimethyl ether, in addition to small amounts of carbon dioxide and formic acid. Overall plant yields are 88—92%. 

The methanol carbonylation is performed ia the presence of a basic catalyst such as sodium methoxide and the product isolated by distillation. In one continuous commercial process (6) the methyl formate and dimethylamine react at 350 kPa (3.46 atm) and from 110 to 120°C to effect a conversion of about 90%. The reaction mixture is then fed to a reactor—stripper operating at about 275 kPa (2.7 atm), where the reaction is completed and DMF and methanol are separated from the lighter by-products. The cmde material is then purified ia a separate distillation column operating at atmospheric pressure. 

In the early 1920s Badische Arulin- und Soda-Fabrik aimounced the specific catalytic conversion of carbon monoxide and hydrogen at 20—30 MPa (200—300 atm) and 300—400°C to methanol (12,13), a process subsequendy widely industrialized. At the same time Fischer and Tropsch aimounced the Synth in e process (14,15), in which an iron catalyst effects the reaction of carbon monoxide and hydrogen to produce a mixture of alcohols, aldehydes (qv), ketones (qv), and fatty acids at atmospheric pressure. 

Manufacture is either by reaction of molten sodium with methyl alcohol or by the reaction of methyl alcohol with sodium amalgam obtained from the electrolysis of brine in a Castner mercury cell (78). Both these methods produce a solution of sodium methylate in methanol and the product is offered in two forms a 30% solution in methanol, and a soHd, which is a dry, free-flowing white powder obtained by evaporating the methanol. The direct production of dry sodium methylate has been carried out by the introduction of methanol vapors to molten sodium in a heavy duty agitating reactor. The sohd is supphed in polyethylene bags contained in airtight dmms filled in a nitrogen atmosphere. 

A process based on a nickel catalyst, either supported or Raney type, is described ia Olin Mathieson patents (26,27). The reduction is carried out ia a continuous stirred tank reactor with a concentric filter element built iato the reactor so that the catalyst remains ia the reaction 2one. Methanol is used as a solvent. Reaction conditions are 2.4—3.5 MPa (350—500 psi), 120—140°C. Keeping the catalyst iaside the reactor iacreases catalyst lifetime by maintaining a hydrogen atmosphere on its surface at all times and minimises handling losses. Periodic cleaning of the filter element is required. 

A few drops of methanol-OD should be added if the solution becomes turbid due to supersaturation. It is advisable to protect the reaction mixture from moisture and oxygen by maintaining the system under an atmosphere of nitrogen. 

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