Propanal from propylene oxide

In a separate study, selectivities to useful products at higher conversions were also investigated, for propane and propylene oxidation, respectively (Figure 4). It was observed, as is common for sequential reactions, that propylene yield from propane, and... 

Figure 4. Propylene Yields from Propane Oxidation and Acrolein Yields from Propylene Oxidation vs. Conversion [12],...

The changeover from ROO radicals to HOO radicals and the switch from organic peroxides to HOOH has been shown as temperature is increased in propane VPO (87,141). Tracer experiments have been used to explore product sequences in propane VPO (142—145). Propylene oxide comes exclusively from propylene. Ethylene, acetaldehyde, formaldehyde, methanol, carbon monoxide, and carbon dioxide come from both propane and propylene. Ethanol comes exclusively from propane. 

After epoxidation, propylene oxide, excess propylene, and propane are distilled overhead. Propane is purged from the process propylene is recycled to the epoxidation reactor. The bottoms Hquid is treated with a base, such as sodium hydroxide, to neutralize the acids. Acids in this stream cause dehydration of the 1-phenylethanol to styrene. The styrene readily polymerizes under these conditions (177—179). Neutralization, along with water washing, allows phase separation such that the salts and molybdenum catalyst remain in the aqueous phase (179). Dissolved organics in the aqueous phase ate further recovered by treatment with sulfuric acid and phase separation. The organic phase is then distilled to recover 1-phenylethanol overhead. The heavy bottoms are burned for fuel (180,181). 

For example, carbon dioxide from air or ethene nitrogen oxides from nitrogen methanol from diethyl ether. In general, carbon dioxide, carbon monoxide, ammonia, hydrogen sulfide, mercaptans, ethane, ethene, acetylene (ethyne), propane and propylene are readily removed at 25°. In mixtures of gases, the more polar ones are preferentially adsorbed). 

V-Sb-oxide based catalysts show interesting catal)dic properties in the direct synthesis of acrylonitrile from propane [1,2], a new alternative option to the commercial process starting from propylene. However, further improvement of the selectivity to acrylonitrile would strengthen interest in the process. Optimization of the behavior of Sb-V-oxide catalysts requires a thorough analysis of the relationship between structural/surface characteristics and catalytic properties. Various studies have been reported on the analysis of this relationship [3-8] and on the reaction kinetics [9,10], but little attention has been given to the study of the surface reactivity of V-Sb-oxide in the transformation of possible intermediates and on the identification of the sxirface mechanism of reaction. 

Freshly distilled propanal (4.4 g, 0.075 mol) was added at room temperature over a period of 20 min to a stirred mixture of benzyl carbamate (7.55 g, 0.05 mol), phenyldichlorophosphine (8.95 g, 0.05 mol), and glacial acetic acid (10 ml). The mixture was refluxed for 40 min, treated with 4 N hydrochloric acid (50 ml), and then refluxed again for 30 min. After cooling, the organic layer was removed, and the aqueous layer was boiled with charcoal (2 g) and evaporated to dryness in vacuum. The residue was dissolved in methanol (40 ml) and treated with propylene oxide until a pH of 6 to 7 was attained. The resultant precipitate was filtered, washed with acetone, and crystallized from methanol/water to give pure (l-aminopropyl)phenylphos-phinic acid (4.08 g, 41%) of mp 256-258°C. 

As mentioned above, it is reasonable to assume that this tetrahedral V species forms at defect sites (hydroxyl nests) in the zeolite framework, but is stabilized by this interaction in a well defined environment through V-O-Si bonds. As indicated by the characterization data, the local coordination of vanadium must be different from that found for well dispersed vanadium sites on silica. This stabilization probably limits the unselective metal-bonded propane or propylene adsorption, in agreement with the role of adsorbate bonding on the selection of partial and total oxidation pathways of ethane on vanadium supported on silica (76) and in agreement with IR evidence (Fig. 

When the commodity chemical propylene oxide is heated to high temperature in the gas phase in a shock tube, unimolecular rearrangement reactions occur that generate the CsHgO isomers allyl alcohol, methyl vinyl edier, propanal, and acetone (Figure 15.9). Dubnikova and Lifshitz carried out a series of calculations to determine the mechanistic pathway(s) for each isomerization, with comparison of activation parameters to those determined from Arrhenius fits to experimental rate data to validate the theoretical protocol. 

Polyethers are typically products of base-catalyzed reactions of the oxides of simple alkenes. More often than not, ethylene oxides or propylene oxides and block copolymers of the oxides are used. A polypropylene oxide-based polymer is built and then capped with polyethylene oxides. An interesting aspect of this chemistry is the use of initiators. For instance, if a small amount of a trifunctional alcohol is added to the reactor, the alkylene oxide chains grow from the three alcohol end groups of the initiator. Suitable initiators are trimethylol propane, glycerol or 1,2,6 hexanetriol. The initiator is critical if one is to make a polyether foam for reasons that we will discuss shortly. 

Propylene oxide in the amount of 5000 tons/yr will be made by the chlorohydrin process. The basic feed material is a hydrocarbon mixture containing 90% propylene and the balance propane which does not react. This material is diluted with spent gas from the process to provide a net feed to chlorination which contains 40 mol % propylene. Chlorine gas contains 3% each of air and carbon dioxide as contaminants. 

Polyurethane is also used as a foam, mostly in sheet form as an underlay or middle layer for example in fruit bins. The following starting materials for polyurethane foam can be used polyester with hydroxyl end groups made from adipic acid, diethylene glycol, trimethylol propane as well as polyether based on ethylene oxide and/or propylene oxide with free hydroxyl groups in combination with 2,4-toluene diisocyanate and 2,6-toluene diisocyanate. Stabilizers, dispersants and amines (as catalysts in amounts up to 1.2 %) can be used. 

In fact, the standard in the industry is that styrene production is integrated from benzene and the ethylene raw material (e.g. propane) through styrene (and propylene oxide for the second process). Styrene production is part of an integrated petrochemical process. 

Acrolein and acrylic acid are both made by vapor phase oxidation of propylene. U.S. 6,281,384 (to E. I. du Pont Nemours and Atofina) describes a fluidized bed process, while U.S. 5,821,390 (to BASF) describes an isothermal reactor cooled by heat transfer to a molten salt. U.S. 6,858,754 and U.S. 6,781,017 (both to BASF) describe alternative processes based on a propane feed. Compare the economics of acrylic acid production from propane with production from propylene. Is the conclusion different if the process is stopped at acrolein ... 

Gold nanoparticles have been used to catalyze the liquid-phase oxidation of ric-diols, e.g., ethylene glycol to glycolic acid.f This may presage an extensive liquid-phase catalytic chemistry. In the gas phase, Au (OH) clusters form adducts with 02. Propylene oxide is formed over Au/Ti02 from a mixture of propylene, H2, and O2. Very small gold particles tend instead to form propane. ° Numerous other applications will surely soon be published. 

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