Olefins longer-chain

Olefins could he catalytically converted into shorter and longer-chain olefins through a catalytic disproportionation reaction. For example, propylene could he disproportionated over different catalysts, yielding ethylene and butylenes. Approximate reaction conditions are 400°C and 8 atmospheres ... 

Nevertheless, the application of ionic liquids in the liquid-liquid, biphasic Rh-catalysed hydroformylation offers technically interesting advantages vs. the traditional aqueous biphasic catalysis e.g. much higher solubility for longer chain olefins and the compatibility of the ionic liquid with phosphite ligands [51]. 

Because the thermal separation of products has been substituted by a liquid-liquid separation, the two phase technology should be best suited for hydroformylation of longer chain olefins. But with rising chain length of the olefins the solubility in the aqueous catalyst phase drops dramatically and as a consequence the reaction rate. Only the hydroformylation of 1-butene proceeds with bearable space-time yield. This is applied on a small scale for production of valeraldehyde starting from raffinate II. Because the sulfonated triphenylphosphane/rhodium catalyst exhibits only slow isomerization and virtually no hydroformylation of internal double bonds, only 1-butene is converted. The remaining raffinate III, with some unconverted 1-butene and the unconverted 2-butene, is used in a subsequent hydroformy-lation/hydrogenation for production of technical amylalcohol, a mixture of linear and branched C5-alcohols. 

Starting from longer-chain olefins means high boiling points of the products, and hence distillation at higher temperatures and vacuum. These demanding conditions cannot be met by the modern rhodium-catalyzed processes. 

Similar oxidations of longer chain olefins provide methyl ketones, however, the reaction is accompanied by olefin isomerization and... 

The Ruhrchemie/Rhone-Poulenc process is performed annually on a 600,000 metric ton scale (18). In this process, propylene is hydroformylated to form butyraldehyde. While the solubility of propylene in water (200 ppm) is sufficient for catalysis, the technique cannot be extended to longer-chain olefins, such as 1-octene (<3 ppm solubility) (20). Since the reaction occurs in the aqueous phase (21), the hydrophobicity of the substrate is a paramount concern. We overcame these limitations via the addition of a polar organic co-solvent coupled with subsequent phase splitting induced by dissolution of gaseous CO2. This creates the opportunity to run homogeneous reactions with extremely hydrophobic substrates in an organic/aqueous mixture with a water-soluble catalyst. After C02-induced phase separation, the catalyst-rich aqueous phase and the product-rich organic phase can be easily decanted and the aqueous catalyst recycled. 

It is immediately apparent from Table 3 why hydrophobic TS-1 is an excellent catalyst for the epoxidation of alkenes and why a polar solvent, like methanol or water, is preferable. On a qualitative basis, it can be understood why the apolar hydrocarbon has a greater affinity for the hydrophobic surface of the pores, whereas water (and methanol) has an affinity for the external polar solution. The concentration of the former in the proximity of active sites is high, while that of the latter is small. It is also predicted that a longer chain olefin (or paraffin) is oxidized faster than a shorter one, as is found experimentally. 

Based on their chain length, olefins converted in commercial oxo plants are divided into four groups ethylene (C2), propene (C3), butene to dodecene (C4 to Cl2) and longer-chain olefins (> C12). The factors influencing product distribution and reaction rates in the hydroformylation of olefins will be discussed in Section 2.1.1.3.3. The economical aspects of 0x0 processes are described in Section 2.1.1.4.1. The share of various products in the overall olefin hydroformylation capacity is C2 2%), C3 (73%), C4-C12 (19%) and >Ci2 (6%). 

Longer chain olefins are similarly epoxidized, with yields in die range of 80-98% (13). The rate of reaction strongly depends on structural features of the olefin including chain length, presence of substituents, and position and steric configuration of the double bond (13). As a result, a different order of reactivity is shown by TS-1 as compared to other epoxidation catalysts a-olefin > internal olefin, linear olefin > branched and cycloolefin, linear-C > linear-C +,. C -2-butene reacts 16 times faster than the trans-isomer (J3). 

This is an important industrial process with 35 plants in operation worldwide, each plant producing between 20,000 and 90,000 t per year of dimer, with a total annual production of 3,500,000 t. The longer-chain olefins produced in the dimerization process are usually hydroformylated to alcohols (e.g., isononanols) isononanols are then converted into dialkyl phthalates, which are used as poly... 

So far the concept of aqueous-organic hydroformylation of alkenes in tubular reactors with static mixers has been applied in a miniplant, that is, a step before a pilot plant. Concerning the possibility of hydroformylating longer chain olefins (up to Cg-Cio), the results are very encouraging. 

An example of a cobalt-based hydroformylation process for long-chain, highly branched olefins is a process developed by Exxon to produce IDA from isomer mixtures of the nonene. There are several recently published patents that describe a further development of this process, thus illustrating that continuous development of the older cobalt technology keeps it competitive for selected challenging hydroformylation processes, such as for complex, highly branched, longer chain olefins. 

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