Propene carbonate

The transesterifications of chloropropene carbonate and propene carbonate with methanol and phenol catalyzed by TS-1, Ti-MCM-41, and Ti02 (Table XLI) have been reported (248). Neither Ti02 nor TS-1 showed any activity in the transesterification reactions. Ti-MCM-41 catalyzed the reaction with a high selectivity for DMC (86%). Ti-MCM-41 also catalyzes the transesterification of cyclic carbonates with phenols (Table XLI). 

This type of process represents the ideal biphasic method as long as the product can be extracted without contamination from the catalyst and catalyst immobilization solvent. This technique is employed commercially for the production of butyraldehyde from propene, carbon monoxide and hydrogen which is described in detail in Chapter 11 [3],... 

The first reports describing the formation of cyclic carbonates (CCs) appeared during the early 1930s [99, 100], whilst the first patents (essentially related to the synthesis of ethene and propene carbonates) appeared more than 50 years ago [101, 102]. The Huntsman Corporation is one the world s largest producers of alkylene carbonates, with a capacity of 33 kt per year, covering approximately 50% of CC production worldwide. Today, CCs are widely used in the manufacture of... 

Different metallic acetates [221] have also been used in acetonitrile, which acts not only as a solvent but also as a dehydrating agent to eliminate the effect of any water produced during the reaction. In this way, the thermodynamic equilibrium could be shifted and the yield of CCs improved. By using 1,2-propene glycol as the reactant (100 mmol) and anhydrous zinc acetate (2.5 mmol) as catalyst in acetonitrile (10ml) with a C02 reaction pressure of 10 MPa, at a reaction temperature of 343 K and a reaction time of 12h, the yield of 1,2-propene carbonate was shown to be 24.2% and the conversion of 1,2-propene glycol 38.9%. 

Studies with gold catalysts have focused on the selective reduction of nitric oxide by propene, carbon monoxide and hydrogen urea,10 methane11 and other hydrocarbons9,11,13 have also been used. NOx removal using the first three of these will now be discussed. 

Raising the temperature increases the amount of gas. At temperatures beyond 550°C, the gas fraction increases rapidly, reaching 42 wt% at 590°C. The gas consists of methane, ethene, propene, carbon monoxide and carbon dioxide (Table 24.2). 

The challenging photochemical reduction of carbon dioxide to formate is catalyzed by Ru" [111] (cf. Section 3.3.4). For example, with the 2,2 -bipyridine-ruthenium(II) complex the active species is formed by photolabilization. Water renders the system more efficient with quantum yields up to 15%. Methanol is the photoproduct when CO2 is reduced with Ti02 in propene carbonate/2-propanol... 

Reduction of NO. with Propene, Carbon Monoxide or Hydrogen... 

The series of nickel molybdates tested for oxidative dehydrogenation of propane produced a product spectrum limited to propene, carbon dioxide, carbon monoxide, and water. No cracking... 

A new development is biphasic hydrogenation using solvent-stabilized colloid (SSCs) catalysts [39-41]. Palladium colloid systems, especially, were proven to give high reactivity and selectivity. Best solvents are dimethylformamide and particularly the two cyclic carbonic acid esters, ethylene carbonate and 1,2-propene carbonate. In these solvents sodium tetrachloropalladate - stabilized by a sodium carbonate buffer - is reduced with hydrogen to yield the solvent-stabilized palladium colloid. Transmission electron microscopy of the palladium colloid demonstrates that the colloid particles are spherical with an average diameter of 4 nm. 

Broad screening of the possible donor solvents proved that only a few solvents are suitable for use in phase separation and colloid stabilization. By far the best results are obtained with propene carbonate (Table 1), which is favored by the high selectivity to C18 1 and the short reaction time. 

It can be assumed that the solvent propene carbonate acts simultaneously as a solvent and as a complex ligand to the palladium. A structural proposal is given in Eq. (2) propene carbonate may coordinate to the metal via two oxygen atoms. If the hydrogen molecule adds to this complex, the carbonate chelate ligand gives... 

Tab. 2 Selective hydrogenation of different oleochemicals with palladium SSCs (T = 25 °C, p = 1 bar H2 solvent propene carbonate).

The propene carbonate-stabilized palladium colloid is an excellent catalyst for the hydrogenation of a great number of different fatty acids, fatty esters, and triglycerides. Table 2 gives a survey of results with sunflower, palm-kernel and rapeseed oils, acids, and esters. The yield of C18 1 products after hydrogenation is in the range of 86-93%. In all examples the reaction time is very short. 

Fig. 1 Kinetics of the selective hydrogenation of sunflower oil fatty acid methyl esters (T = 25°C, solvent propene carbonate Pd/ester ratio 1 5000).

Various other rhodium catalysts can initiate hydroacylation reactions. Thus, the indenyl complex [075-C9H7)Rh(J72-C2H4)2] is used in intermolecular hydroacylation44. Rhodium zeolites (RhNaX and RhNaY type zeolites) act as bifunctional catalysts for the synthesis of 2-methyl-3-hexanone and 4-heptanone (1 2 ratio) from propene, carbon monoxide and hydrogen53. In this case, the ketones may be formed via hydrocarbonylation (vide supra), however, according to control experiments, rhodium-free zeolites alone catalyze ketone formation from propene and butyraldehyde53. 

The consecutive isomerization-hydroformylation reaction of trans-4-octene yields high conversion and high selectivity of n-nonanal in the polar solvent propene carbonate [Eq. (8)] [33]. 

The hydrosilylation of methyl 10-undecenoate with triethoxysilane catalyzed by anhydrous H2PtClg was studied in the thermomorphic solvent system propene carbonate (sl)/cyclohexane (s2)/toluene (s3) [Eq. (9)] [18]. 

The conversion finishes after 15 s and gives 80% of product 20 at 80 °C under single-phase conditions. Cooling brings about a partition of the ternary solvent mixture. The nonpolar phase (cyclohexane) contains the product, the polar phase (propene carbonate) the catalyst. 

Apart form being an excellent solvent, SCCO2 can also be used as a very effective reagent [37] (see Chapter 6). In the preparation ofpropene carbonate, carbon dioxide was used together with propene oxide as starting materials. The related study was carried out in the IL [OMIM][BF4] and the TOF values obtained for the production of propene carbonate were 77 times higher than any values reported in the Hteratare for this particular reaction. 

Cyclic carbonates can be prepared by chemical fixation of CO2, which is a much more environmentally acceptable process than that using phosgene. The formation of propene carbonate has been achieved in CO2-IL systems, whereby CO2 serves as a reagent rather than a reaction medium [Eq. (9)] [49]. The production of cyclic carbonates has suffered in the past from serious disadvantages of separating the catalyst [50, 51], while the activity of heterogeneous catalysts is generally very poor [52]. 

Polycarbonates have long been produced by using phosgene. This field is now moving to new synthetic strategies based on (1) the direct copolymerization of olefin-oxides and CO2 (propene carbonate, Novomer), (2) the use of CO2 substitutes (organic carbonates formed from CO2) if the epoxide is not easily produced (this is the case of BP-A), or (3) the polymerization of preformed monomeric carbonates, as represented in Scheme 6.24. The latter would produce a very regular polymer characterized by 50 % CO2 and co-monomer. 

Propene carbon monoxide copolymerization regio- and stereoselectivity 811... 

Figure 40 Linear and spiroketal structure of propene/carbon monoxide-based polyketones.

X represents oxygen in DME and methanol carbonyl carbon in acetaldehyde and acetone vinylic secondary carbon in propene carbon in ethane. 

Tacticity studies have been conducted on poly(3-methyl-l-butene) [120], poly(p-isopropyl-a-methyl styrene) [121], a-methyl styrene [122], polytetrafluoroethylene [123], polyacrylic acid [124], polymethylvinyl ethers [125], polyacrylonitrile [126, 127], polyvinyltrifluoro acetate [128], polyvinyl alcohol and its ethers [129, 130], isobutene-maleic anhydride [111], isobutene dimethyl fumerate [131], isobutene dimethyl maleate [131], polyacrylonitrile [127], ethylene - vinyl acetate [132-135], polyalkyl vinyl ethers [136, 137], ethyl-2-chloroacetate [133], poly-trans-1,3-pentadiene [138], isotactic-l-butene - propylene [139], butadiene - propylene [140], polybutene [141], polychloroprene [142], ethylene - vinyl chloride [143], chlorinated polyethylene [144, 145], poly-a-methyl styrene [146], styrene acrylic acid [147], a-methyl styrene - methacylonitrile [148], styrene acrylonitrile [149], styrene isobutene [150], poly(p-fluoro-a-methyl styrene) [151], polyarylamide-6 [152], PP - polyamide-6 [152], polystyrene oxide [153], polybutene [154], atraconic anhydride - p-chlorostyrene [155], styrene - maleic anhydride [156, 157], ethylene - vinyl acetate [158], polymethyl vinyl ether [159], propene - carbon monoxide [160], methyl(3,3,3-trifluoropropyl)siloxane [161], poly(diallyldimethyl ammonium chloride) [162], polypropene [163, 164], polyepichlorohydrin [165], maleic anhydride-p-chlorostyrene [166], polymethacrylonitrile [167] and polyvinyl acetate [168]. 

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