Basic by-products

Compounds containing an Si-N bond are usually susceptible to hydrolysis. In the same way that hydrolysis of a compound giving an acid requires a base to be present for neutralization, if the reaction yields a basic by-product, such as NH3 in the hydrolysis of (Me3Si)2NH, then dilute aqueous HC1 may be used for the hydrolysis, thus neutralizing... 

Cu(OTf)2 generally gives yields intermediate between those of the other two catalysts, but with a closer resemblance to rhodium. In competition experiments, the better coordinating norbomene is preferred over styrene, just as in the case with Pd(OAc)2. Cu(acac)2, however, parallels Rh2(OAc)4 in its preference for styrene. These findings illustrate the variability of copper-promoted cyclopropanations, and it was suggested that in the Cu(OTf)2-catalyzed reactions of diazoesters, basic by-products, which are formed as the reaction proceeds, may gradually suppress... 

Naess, O., and Rasmussen, K. E. (1997). Micellar electrokinetic chromatography of charged and neutral drugs in acidic running buffers containing a zwitterionic surfactant, sulfonic acids or sodium dodecyl sulphate — separation of heroin, basic by-products and adulterants. /. Chromatogr. A 760, 245-251. 

In conclusion, decrease in cyclohexanone oxime yield and caprolactam selectivity with time on stream is a major factor in the use of boria on alumina catalyst in the rearrangement reaction. Coke deposition and basic by-product adsorption have been suggested as a means of deactivation. In addition the conversion of water soluble boron, which is selective to lactam formation, to an amorphous water insoluble boron species is another factor that can account for the catalyst deactivation. 

Catalyst is acidic and is especially deactivated by Nylons and other polymers that produce alkaline (i.e. basic) by-products. 

Nitro-2-naphthylamine in chloroform treated at room temp, with a soln. of bromine in chloroform, the resulting hydrobromide collected after 24 hrs., washed with chloroform, which is then removed in vacuo, the product suspended in ice-water and treated with aq. NH3 l-bromo-3-nitro-2-naphthylamine. Y 95%.—This is an excellent preparative method. The amines are readily soluble in the cold solvent the HBr liberated forms the insoluble hydrobromide of most of the product. This can be removed by filtration, usually in high yield, and invariably in a high state of purity since non-basic by-products re-... 

The enzyme oxinitrilase also catalyzes the addition of prussic acid to 3-phenoxy benzaldehyde 2S0 in a moderate enantioselective manner to give the unsuitable R-enantiomer of299 [640,641]. An artificial enzyme proved to be much more efRcient. The cyclic dipeptide cyclo-(R-Phe-R-His) 300 catalyzes the enantioselective HCN-addition onto aldehydes [642] (Reaction scheme 213). In the case of 3-phenoxy benzaldehyde the desired S-enantiomer 299 is created with a high optical and chemical yield [643-646] optimally in the absence of water in aprotic solvents, catalyzed by some cyanohydrine [647] or aralkyl-alcohol [618]. Rigorous exclusion of traces of basic by-products and a preceding acidic purification step [649] gives additional improvement. 

Each aspiration step by the Quadra 96 is generally proceeded by 50 pL of air gap to aid in complete and accurate dispensing. This extraction procedure is used to remove excess amines or other basic by-products and impurities in the final combinatorial products. It takes advantage of the difference in basicity between the impurities such as amines (pK 9.5-10.5 for most of their conjugate acids or amonium ions) and the desired produet (pK < 0 for most of their conjugate acids). Therefore, amines are protonated cations at a neutral pH and retained by the cation exchange SPE resins, while the desired product is not. If basic ionizable final products (e.g., amines) are to be purified and nonionizable impurities are to be removed, then an additional final elution step with a basic solvent (e.g., 1 mL of 2 M anunonia in methanol) is needed to obtain the desired final product that is retained on the resins after step g. 

Many of the reactions listed at the beginning of this section are acid catalyzed, although a number of basic catalysts are also employed. Esterifications are equilibrium reactions, and the reactions are often carried out at elevated temperatures for favorable rate and equilibrium constants and to shift the equilibrium in favor of the polymer by volatilization of the by-product molecules. An undesired feature of higher polymerization temperatures is the increased probability of side reactions such as the dehydration of the diol or the pyrolysis of the ester. Basic catalysts produce less of the undesirable side reactions. 

Furfuryl alcohol alone, or in combination with other cross-linkable binders such as phenoHc reins, chemical by-products and pitch, catalyzed with acid, gives carbon yields of 35—56%. Furfural together with cyclohexanone, pitch, or phenoHc resins gives, under acid catalysis, yields of 35—55% carbon under basic catalysis yields of 5—50% are achieved. FurfuryHdeneacetone resins (13 and 14), catalyzed by acid or base, give carbon yields of 48—56 and... 

Since adipic acid has been produced in commercial quantities for almost 50 years, it is not surprising that many variations and improvements have been made to the basic cyclohexane process. In general, however, the commercially important processes stiU employ two major reaction stages. The first reaction stage is the production of the intermediates cyclohexanone [108-94-1] and cyclohexanol [108-93-0], usuaHy abbreviated as KA, KA oil, ol-one, or anone-anol. The KA (ketone, alcohol), after separation from unreacted cyclohexane (which is recycled) and reaction by-products, is then converted to adipic acid by oxidation with nitric acid. An important alternative to this use of KA is its use as an intermediate in the manufacture of caprolactam, the monomer for production of nylon-6 [25038-54-4]. The latter use of KA predominates by a substantial margin on a worldwide basis, but not in the United States. 

CO, and methanol react in the first step in the presence of cobalt carbonyl catalyst and pyridine [110-86-1] to produce methyl pentenoates. A similar second step, but at lower pressure and higher temperature with rhodium catalyst, produces dimethyl adipate [627-93-0]. This is then hydrolyzed to give adipic acid and methanol (135), which is recovered for recycle. Many variations to this basic process exist. Examples are ARCO s palladium/copper-catalyzed oxycarbonylation process (136—138), and Monsanto s palladium and quinone [106-51-4] process, which uses oxygen to reoxidize the by-product... 

In earlier studies (24), the reaction was carried out at temperatures above 200°C under autogenous pressure conditions usiag alkaU metal hydroxide or alkoxide catalysts significant amounts of carboxyUc acid, RCH2COOH, were formed as were other by-products. More recent reports describe catalysts which minimize by-products MgO—K CO —CUC2O2 (25), less basic but stiU requiring high temperatures Rh, Ir, Pt, or Ru complexes (26) and an alkaU metal alkoxide plus Ni or Pd (27), effective at much lower temperatures. 

The degree of duorination can be limited by the thermal stabiUty of the solvent or by its reaction with basic potassium duoride through proton abstraction. Such solvent-derived by-products can subsequentiy react with the starting material and/or main product. 

The methanol carbonylation is performed ia the presence of a basic catalyst such as sodium methoxide and the product isolated by distillation. In one continuous commercial process (6) the methyl formate and dimethylamine react at 350 kPa (3.46 atm) and from 110 to 120°C to effect a conversion of about 90%. The reaction mixture is then fed to a reactor—stripper operating at about 275 kPa (2.7 atm), where the reaction is completed and DMF and methanol are separated from the lighter by-products. The cmde material is then purified ia a separate distillation column operating at atmospheric pressure. 

Russian Process Technology. Magnesium production ia the former Soviet Union is apparently done via molten chloride electrolysis (29,30). The basic process uses camaOite [1318-27-0], MgCl2 KCl 6H20, either from natural deposits or as a by-product of processiag natural salt deposits, as its... 

The resulting discoveries may provide a broad range of solutions or products. For example, invention may result from basic research and development efforts directed toward products which ate essential to basic commercial efforts. Alternatively, invention may result in products or appHcations which add value to basic commercial products that ate already in existence. Inventions may also be used to assist an individual or company in commercial efforts toward developing a defensive posture in any given marketplace. When patented, appHcations may also provide an extended opportunity to Hcense or market the patent without the actual production of a product by the inventor. 

In the preparation of hydroperoxides from hydrogen peroxide, dialkyl peroxides usually form as by-products from the alkylation of the hydroperoxide in the reaction mixture. The reactivity of the substrate (olefin or RX) with hydrogen peroxide is the principal restriction in the process. If elevated temperatures or strongly acidic or strongly basic conditions are required, extensive decomposition of the hydrogen peroxide and the hydroperoxide can occur. 

This scheme eliminates the process of converting bis(etherimide)s to bis(ether anhydride)s. When polyetherimides are fusible the polymerization is performed in the melt, allowing the monamine to distill off. It is advantageous if the amino groups of diamines are more basic or nucleophilic than the by-product monoamine. Bisimides derived from heteroaromatic amines such as 2-arninopyridine are readily exchanged by common aromatic diamines (68,69). High molecular weight polyetherimides have been synthesized from various N,lSf -bis(heteroaryl)bis(etherimide)s. 

Most alkylphenols sold today require refinement. Distillation is by far the most common separation route. Multiple distillation tower separations are used to recover over 80% of the alkylphenol products in North America. Figure 4 shows a basic alkylphenol distillation train. Excess phenol is removed from the unrefined alkylphenol stream in the first tower. The by-products, which are less volatile than phenol but more volatile than the product, are removed in the second tower. The product comes off the third tower overhead while the heavy by-products come out the bottom. 

V-Trimethyl silyl diethyl amine (TMSDEA) is a stroagly basic silylatiag reageat and is particulady usehil for derivatiziag low molecular weight acids. The reaction by-product, diethylamine, is volatile enough to be easily removed from the reaction medium. 

Carbonates undergo nucleophilic substitution reactions analogous to chloroformates except in this case, an OR group (rather than chloride) is replaced by a more basic group. Normally these reactions are cataly2ed by bases. Carbonates are sometimes preferred over chloroformates because formation of hydrogen chloride as a by-product is avoided, which simplifies handling. However, the reactivity of carbonates toward nucleophiles is considerably less than chloroformates. 

Dehydrogenation is considered to occur on the corners, edges, and other crystal defect sites on the catalyst where surface vacancies aid in the formation of intermediate species capable of competing for hydrogen with ethylbenzene. The role of the potassium may be viewed as a carrier for the strongly basic hydroxide ion, which is thought to help convert highly aromatic by-products to carbon dioxide. 

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