Conventional method of preparation

Seb cic Acid. Sebacic acid [111-20-6] C QH gO, is an important intermediate in the manufacture of polyamide resins (see Polyamides). It has an estimated demand worldwide of approximately 20,000 t/yr. The alkaline hydrolysis of castor oil (qv), which historically has shown some wide fluctuations in price, is the conventional method of preparation. Because of these price fluctuations, there have been years of considerable interest in an electrochemical route to sebacic acid based on adipic acid [124-04-9] (qv) as the starting material. The electrochemical step involves the Kolbn-type or Brown-Walker reaction where anodic coupling of the monomethyl ester of adipic acid forms dimethyl sebacate [106-79-6]. The three steps in the reaction sequence from adipic acid to sebacic acid are as follows ... 

A review of the commonly used experimental methods for solubility determinations is presented in Table 1. Briefly, batch equilibration is the conventional method of preparing saturated solutions for solubility determinations, where an excess amount of solute chemical is added to water and equilibrium is achieved... 

Optical fibres need to be free of impurities such as transition metal ions (see Chapter 8) and conventional methods of preparing silica glasses are inadequate. The sol-gel process is one way of forming fibres of sufficient purity (chemical vapour deposition. Section 3.7, is another). These processes use volatile compounds of silicon which are more easily purified, for example by fractional distillation, than silica. It is possible to produce silica fibres using a method similar to that studied in the nineteenth century, but with the geldrying time reduced from a year to a few days. Liquid silicon alkoxide (Si(OR)4), where R is methyl, ethyl, or propyl, is hydrolysed by mixing with water. 

The conventional method of preparing biodiesel is an alkaline catalysed transesterification reaction of refined vegetable oils with methanol to produce biodiesel according to E.U. (EN14214) or U.S. (ASTM D6751) standards. 

Phenol-formaldehyde resins find numerous applications in such areas as wood composites, fiber bonding, laminates, foundry resins, abrasives, friction and molding materials, coatings and adhesives, and flame retardants (JL). From a specialty chemicals standpoint, they are also used as developer resins in carbonless papers (2.). Conventional methods of preparation involve condensation of a phenol with formaldehyde under either acidic (novolak) or basic (resole) conditions (2). Their typical molecular weight range is from 800-4000 daltons (D) and includes a wide variety of alkyl or aryl substituted phenols (A)- The... 

This method is much quicker than the conventional method of preparing camphor-free cytochrome by Sephadex G-10 chromatography (Sharrock et al., 1973). With a flow rate of 2 ml min-1, the time required to obtain the cytochrome P-450 is only 3—4 minutes. 

The conventional method of preparation of these aromatic ketones is the homogeneous Friedel-Crafts acylation of aromatic hydrocarbons with carboxylic acid derivatives using Lewis acids (A1C13, FeCl3, BF3, ZnCl2, TiCl4) or Bronsted acids (polyphosphoric acid, HF). For this purpose, stoichiometric to excess amounts of the catalyst are required for the reaction to proceed (ref. 1). 

Conventional methods of preparation of magnesium oxide yield products that have large and varied grain sizes and fairly low surface areas. The most popular method of nanoparticle synthesis has been via sol-gel processing. Other liquid-phase methods involve the use of hydrothermal synthesis, which has yielded rod, tube, and needle-shaped morphologies (Ding et al., 2001). Klabunde (2001) has reviewed the various synthetic methods. 

Onee the acid leached solution was obtained it was treated with equivalent amount of (NH4)2C03 as per the report in the literature [2] and as well as with NaOH. As reported earlier, the preeipitates were difficult to filter and wash. The dried cake was hard, brittle with high sulphate content. Conventional methods of preparation of this type of catalyst normally use Fe(II)-Sulphate as a raw material. The stock solution was, therefore successively piled with FeS04.7H20 and the eharacteristics of the precipitate improved substantially as concentration of Fe(II) ions was increased in the system. It is known from published literature [10] that OoeOFeOOH is generated when precipitated from a solution containing stoichiometric quantity of Fe(III) and Fe(ll) ions. 

Reaction 27.17 is one conventional method of preparing BaTi03. A second route (used industrially) involves the preparation of BaTiO(ox)2-4H20 (ox = oxalate) from BaCl2, TiCl4, H2O and H2OX, followed by thermal decomposition (scheme 27.18). 

Conventional methods of preparing thin sections of cells or nuclei for electron microscopy (employing chemical fixation, room-temperature dehydration. 

There are a lot of other methods for QDs synthesis such as microwave-assisted synthesis, cation-exchange-based synthesis, " seeded synthesis," polymer-templated synthesis, and a top-down approach. These methods could serve as alternatives to the conventional methods of preparing QDs with the desired properties, especially for those that are diffieult to prepare... 

It proved possible to modify retinoids by electrolytic reductions. However, the few examples disclosed hitherto do not show any advantages over the conventional methods of preparative organic chemistry. Retinyl acetate (9) was reduced to axerophthene (568) in very good yield at a potential of —2.0 V in dimethylfor-... 

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