Solubility alkenes

The use of amphiphilic water-soluble ligands which influence the alkene solubility or increase the catalyst concentration at the interface area of the phases [48,49] ... 

Alkene Solubility at room temperature/ppm Calculated solubility of liquid alkane at 25 °C/ppm... 

Dror and Manassen [82] stated that the reaction depends on the alkene solubility in the aqueous phase and that a co-solvent should be helpful. This leads to the recommendation of co-solvents (e. g. [29, 35, 75, 81]). Delmas, Jenck and coworkers [83] investigated the influence of co-solvents or hydrogen on alkene (oc-tene) solubility in the aqueous phase, using predicted liquid/liquid equilibria within the frame of a thermodynamie model. The distinction of two types (A and B) of ternary diagrams, depending on the slope of the lines, with various oc-tene-in-water and water-in-organic phases, explains the ambiguous statements in the literature about the effectivity of solvents. 

The concept of biphasic catalysis requires that the catalyst and product phases separate rapidly to achieve a practical approach to the recovery and recycling of the catalyst. It is obvious that simple aqueous/hydrocarbon systems form two phases under nearly all operating conditions and thus provide rapid product-catalyst separation. Ultimately, however, the application of water-soluble catalysts is limited to low-molecular-mass substrates which have appreciable water-solubility. The problem is illustrated by the data in Table 1, which gives the solubility of some simple alkenes in water at room temperature [1], Although hydrocarbon (alkene)-solubility in water increases at higher temperature, most alkenes do not have sufficient solubility to give practical reaction rates in catalytic applications. The addition of salts further decreases the solubility of hydrocarbons in water. Substrate solubility in water is a significant issue and it is no accident that so-far the practiced and proposed commercial applications of water-soluble catalysts for hydroformylation are limited to propene and butene. 

The consequence of low alkene solubility is in that industrially the RCH-RP process can be used only for the hydroformylation of C2-C4 olefins. In all other cases the overall production rate becomes unacceptably low. This is what makes the hydroformylation of higher olefins one of the central problems in aqueous/organic biphasic catalysis. Many solutions to this problem have been suggested (some of them will be discussed below), however, any procedure which increases the mutual solubility of the organic components and the aqueous ingredients (co-solvents, surfactants) may... 

The problem of low conversion was largely caused by poor mass transport of the substrate into the IL, where the catalyst resides. Significant improvements were obtained by increasing the chain length of the 1-alkyl in the imidazolium cations (Figiue 8) probably because of the known increase in alkene solubility [3],... 

Kilaru, P. Scovazzo, P. (2008). Correlations of low pressure carbon dioxide and alkenes solubilities in imidazolium-, phosphonium-, and ammonium-based room temperature ionic liquids. Part II. Using activation energy of viscosity, Ind. Eng. Ghent. Res., 47,910-919, ISSN 0888-5885. 

Dimethyl acetylenedicarboxylate (DMAD) (125) is a very special alkyne and undergoes interesting cyclotrimerization and co-cyclization reactions of its own using the poorly soluble polymeric palladacyclopentadiene complex (TCPC) 75 and its diazadiene stabilized complex 123 as precursors of Pd(0) catalysts, Cyclotrimerization of DMAD is catalyzed by 123[60], In addition to the hexa-substituted benzene 126, the cyclooctatetraene derivative 127 was obtained by the co-cyclization of trimethylsilylpropargyl alcohol with an excess of DMAD (125)[6l], Co-cyclization is possible with various alkenes. The naphthalene-tetracarboxylate 129 was obtained by the reaction of methoxyallene (128) with an excess of DMAD using the catalyst 123[62],... 

Alkynes resemble alkanes and aUcenes m their physical properties They share with these other hydrocarbons the properties of low density and low water solubility They are slightly more polar and generally have slightly higher boiling points than the corre spondmg alkanes and alkenes... 

The physical properties (boiling point solubility m water dipole moment) of alkynes resemble those of alkanes and alkenes... 

The carbonyl oxygen of aldehydes and ketones can form hydrogen bonds with the pro tons of OH groups This makes them more soluble m water than alkenes but less solu ble than alcohols... 

Hydrophilic (Section 19 5) Literally water loving a term applied to substances that are soluble in water usually be cause of their ability to form hydrogen bonds with water Hydrophobic (Section 19 5) Literally water hating a term applied to substances that are not soluble in water but are soluble in nonpolar hydrocarbon like media Hydroxylation (Section 15 5) Reaction or sequence of reac tions in which an alkene is converted to a vicinal diol Hyperconjugation (Section 4 10) Delocalization of a electrons... 

In cases where the alkene is soluble, up to 30 S of the aqueous DMF can be mixed with the alkene to facilitate controlled addition. With 1-decene, QHF forms a two-phase mixture. 

Alkenes — Also known as olefins, and denoted as C H2 the compounds are unsaturated hydrocarbons with a single carbon-to-carbon double bond per molecule. The alkenes are very similar to the alkanes in boiling point, specific gravity, and other physical characteristics. Like alkanes, alkenes are at most only weakly polar. Alkenes are insoluble in water but quite soluble in nonpolar solvents like benzene. Because alkenes are mostly insoluble liquids that are lighter than water and flammable as well, water is not used to suppress fires involving these materials. Because of the double bond, alkenes are more reactive than alkanes. 

The oxidation of alkenes and allylic alcohols with the urea-EL202 adduct (UELP) as oxidant and methyltrioxorhenium (MTO) dissolved in [EMIM][BF4] as catalyst was described by Abu-Omar et al. [61]. Both MTO and UHP dissolved completely in the ionic liquid. Conversions were found to depend on the reactivity of the olefin and the solubility of the olefinic substrate in the reactive layer. In general, the reaction rates of the epoxidation reaction were found to be comparable to those obtained in classical solvents. 

When water-miscible ionic liquids are used as solvents, and when the products are partly or totally soluble in these ionic liquids, the addition of polar solvents, such as water, in a separation step after the reaction can make the ionic liquid more hydrophilic and facilitate the separation of the products from the ionic liquid/water mixture (Table 5.3-2, case e). This concept has been developed by Union Carbide for the hydroformylation of higher alkenes catalyzed by Rh-sulfonated phosphine ligand in the N-methylpyrrolidone (NMP)/water system. Thanks to the presence of NMP, the reaction is performed in one homogeneous phase. After the reaction. 

Physical properties of alkynes [49, p. 251] are essentially similar to those of alkanes and alkenes. These compounds are weakly polar and are insoluble in water, but they are quite soluble in organic solvents of low polarity (e.g., ether, benzene, CCl ). Chemically, alkynes are more reactive than alkanes but behave like alkenes. The triple bond appears to be less reactive than the double bond in some reagents while more reactive in others. In a chemical reaction, the triple bond is usually broken into a double bond, which may eventually split into single bonds. 

Ethylene (ethene), the first member of the alkenes, is a colorless gas with a sweet odor. It is slightly soluble in water and alcohol. It is a highly... 

In practice, few alkenes are soluble in water, and bromohydrin formation is often carried out in a solvent such as aqueous dimethyl sulfoxide, CH3SOCFI3 (DMSO), using a reagent called W-brornosuccinimide ( rBS) as a source of Br2. NBS is a stable, easily handled compound that slowly decomposes in water to yield Br2 at a controlled rate. Bromine itself can also be used... 

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