Catalysed product

The process of anionic polymerisation was first used some 60 or more years ago in the sodium-catalysed production of polybutadiene (Buna Rubbers). Typical catalysts include alkali metals, alkali metal alkyls and sodium naphthalene, and these may be used for opening either a double bond or a ring structure to bring about polymerisation. Although the process is not of major importance with the production of plastics materials, it is very important in the production of synthetic rubbers. In addition the method has certain special features that make it of particular interest. 

While many virtues of enzyme catalysis need to be recognized, it should be realized that industrial enzymes can cost from US 10,000 to 11,000 per kg. Therefore, the enzyme catalysed production of chemicals that sell at US 1 to 5 per kg may not be economical even if the yield is 100 % and downstream cost is not excessive. Enzymes are easier to justify for pharmaceutical that sell at US 30 to 50,000 per kg. Even noble metal catalysts like 5% Pd on carbon cost about US 720 per kg. 

Colloids of metals with practically zero overpotential for Hj evolution such as platinum and iridium are very efficient at catalysing production. The transferred electrons are immediately converted into adsorbed H atoms which then undergo the Heyrovsky reaction to form Hj e + H -h H2. The gold microelectrode... 

Equation 9.1 Commercialised Lewis acid catalysed production of dihydrofuran in a phosphonium ionic... 

The energy released is used to transfer protons across the photosynthetic membrane and ultimately this energy acts as a driving force for the catalysed production of high-energy adenosine triphosphate (ATP) from adenosine diphosphate (ADP) and inorganic phosphate. 

Metal-catalysed hydrocarboxylation of olefins (Equation 3) is the poor relative of the more famous hydroformylation. It generally requires forcing reaction conditions and suffers from mediocre activities and selectivities (n/i ratio). Moreover, the same products can be made via hydroformylation and oxidation of the aldehyde product.431 Consequently, there are few industrial applications of hydrocarboxylation e.g. Ni(CO)4-catalysed production of propionic acid by hydrocarboxylation of ethylene.432,433... 

Behnke W, Elend M, Kruger U, Zetzsch C (1999) The Influence of NaBr/NaCl Ratio on the BU-Catalysed Production of Halogenated Radicals. J Atmos Chem 34 87... 

Acetic anhydride is also produced by the Rh-catalyzed carbonylation of methyl acetate. The method is called the Eastman process (Scheme 3.11). The Rh-catalysed production of acetic anhydride from methyl acetate can be understood by the formation of Mel and acetic acid by the reaction of methyl acetate with HI. Finally, attack of AcOH on the acetylrhodium affords the anhydride and HI, or acetyl iodide reacts with AcOH to give acetic anhydride and HI. 

A widely studied example of this kind is the synthesis of methyl isobutyl ketone (MIBK, used as a solvent for inks and lacquers) from acetone. The former was previously prepared from the latter through a catalytic three-step process base-catalysed production of 4-hydroxy-4-methylpentan-2-one, acid dehydration into mesityloxide (MO), then hydrogenation of MO on a Pd catalyst. Since acetone aldolization occurs through acid catalysis as shown over a H-MFI zeolite at 433 K (MO is the main reaction product, the aldolization product being rapidly dehy-drated[5]), it is possible, by associating with the acid catalyst a hydrogenation phase,... 

Almatawah, Q.A. and Cowan, D.A. 1999. Thermostable nitrilase catalysed production of nicotinic acid from 3-cyanopyridine. Enzyme Microbiology and Technology, 25 718-24. 

Mathew, C.D., Nagasawa, T., Kobayashi, M., et al. 1988. Nitrilase-catalysed production of nicotinic acid from 3-cyanopyridine in Rhodococcus rhodochrous 11. Applied and Environmental Microbiology, 54 1030-2. 

A new process for the heterogeneously-catalysed production of campholenic aldehyde from a-pinene oxide has been found which is competitive with the homogeneous ZnBr2 system and gives yields up to 85%. 

The isomerization of styrene oxide to phenylacetaldehyde yields 100% using modified ZSM-5 zeolites, thereby the highest target achieved by catalysis has been fulfilled. A new process as well has been found for the heterogeneously-catalysed production of campholenic aldehyde from a-pinene oxide. By using low reaction temperatures of 0 °C and below in combination with HCl-treated H-US-Y zeolites, up to 85% yield is achieved. This process is competitive with the homogeneous ZnBr2 system. 

Dossat, V Combes, D Marty, A. Efficient lipase catalysed production of a lubricant and surfactant formulation using a continuous solvent-free process. Journal of Biotechnology, 2002, v. 97, 117-124. 

Heathcock s group has investigated the buffered acetolysis of the 9-methyl-l-decalyl tosylates (376)—(379) and the keto-olefinic products were reduced to hydrocarbons for the purpose of analysis. The major products from (376) were (380) (78%), (381) (5%), and (382) (10%). Tosylate (377) gave (380) (80%) and (381) (15 %). Acid-catalysed product equilibration gave (380) (28 %), (381) (52%), and (382) (14%). No anchimeric assistance to ionization was noted in the kinetic experiments and no methyl-migrated products were found from (377) rapid rearrangement to the more stable ion (383) occurred after the transition state to ionization had been passed. Products may then arise from (383) or (384) as indicated (Scheme 16). cis-Tosylate (379) may react via either... 

The calculated reactive halogen concentrations of 10-40 pmol moF should be detectable in the field. The main daytime species are HOBr and HOCl, whereas at night BrCl and Br2 are most abundant. Our calculated daytime BrO concentrations reach values of 10 -10 molecules cm, which is in the detection range of differential optical absorption spectroscopy (DOAS). Some experimental evidence already exists [30] for the proposed Br catalysed production of Cl from sea-salt aerosol, which was irradiated in a large reaction chamber in the presence of O3. 

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