Catalyst synthesis primary, secondary

The Fischer-Tropsch synthesis, which may be broadly defined as the reductive polymerization of carbon monoxide, can be schematically represented as shown in Eq. (1). The CHO products in Eq. (1) are any organic molecules containing carbon, hydrogen, and oxygen which are stable under the reaction conditions employed in the synthesis. With most heterogeneous catalysts the primary products of the reaction are straight-chain alkanes, while the secondary products include branched-chain hydrocarbons, alkenes, alcohols, aldehydes, and carboxylic acids. The distribution of the various products depends on both the type of catalyst and the reaction conditions employed (4). 

A more detailed description of heterogeneous catalyst library synthesis (primary and secondary), primary screening, and secondary screening technologies is given in Chapter 3 and references therein. 

The state-of-the-art catalyst system is a Mo-V-Nb-Te mixed oxide [52], This catalyst is quite sensitive to its synthesis and process parameters and the automated catalyst synthesis tools described above were capable of synthesizing these and other challenging mixed metal oxides successfully. The workflow was validated by synthesizing a region of the known Mo-V-Nb-Te catalyst system phase space in the primary scale and secondary scale (Fig. 3.19a and b). Very good agreement between primary, secondary, and literature optima were obtained. One of the pri-... 

Dialkyl peroxides (1), R-O-O-R (R and R are = or primary, secondary, tertiary alkyl, cycloalkyl, aralkyl and heterocyclic radicals Homolytic decompn when heated or irradiated with prodn of free radicals for org synthesis difficult to hydrolyze and reduce rearrangement crosslinking and polymerization polymeric peroxides are thick liqs or amorph wh powds used as polymerization catalysts Primary radicals are unstable, lowest members such as dimet peroxide are shock sens and dangerous expls sensitivity lessens with increasing mw polymeric peroxides (copolymers of olefins and Oj) explode on heating... 

Similar synthesis of 5-alkyl- or 5-arylthio-3//-l,2-dithiole-3-thiones 267 from dithiomalonic esters 265 containing phenyl, benzyl, or primary, secondary, and tertiary alkylthio group at the C-5 position was accomplished with (1) P4S10/S8 in boiling xylene in the presence of 2-mercaptobenzothiazole/ZnO as catalyst, or (2) with LR as sulfurizing reagent (Scheme 47) <2002TL1947>. 

All classes of vicinal diols (primary, secondary, tertiary, alkyl- or aryl-substituted) will undergo the pinacol rearrangement, and many acids and solvents have been used for this purpose. Various procedural modifications have been introduced over the years for particular glycols, but sulfuric acid remains the most commonly employed catalyst. The use of 25% H2SO4, as recommended in the procedure of Adams, affords pinacolone in essentially quantitative yield. In some instances better results are obtained when cold concentrated acid is used as the solvent. The choice of reagents and conditions is important, and can completely alter the course of the reaction. For example, pinacol also serves as the starting material for the synthesis of 2,3-dimethylbutadiene, formed by slow distillation of a mixture of the diol and catalytic HBr. ... 

Solution-polymerized SBR is made by termination-free, anionic/live polymerization initiated by alkyl lithium compounds. Other lithium compounds are suitable (such as aryl, alkaryl, aralkyl, tolyl, xylyl lithium, and ot/p-naphtyl lithium as well as their blends), but alkyl lithium compounds are the most commonly used in industry. The absence of a spontaneous termination step enables the synthesis of polymers possessing a very narrow molecular weight distribution and less branching. Carbon dioxide, water, oxygen, ethanol, mercaptans, and primary/secondary amines interfere with the activity of alkyl lithium catalysts, so the polymerization must be carried out in clean, near-anhydrous conditions. Stirred bed or agitated stainless steel reactors are widely used commercially. 

Reductive alkylation is an effective method to synthesize secondary and tertiary amines from primary amines and hence is practiced commercially for the synthesis of a variety of fine and specialty chemicals. These inclnde corrosion inhibitors snch as the derivatives of cyclohexylamine, mbber chemicals such as A-(l,3-dimethylbutyl)-A -phenyl-p-phenylenediamine (6-PPD see Figure 15.13), pharmaceutical intermediates, dye intermediates, and pesticides [66-70]. The reaction starts ont as the condensation of an amine with a carbonyl compound followed by rednction of the intermediate imine (a Schiff base) to the desired amine. If the carbonyl componnd has an a-proton that can be abstracted, this secondary amine can be further reduced to tertiary amine [65]. Dne to the relatively small volume of such chemicals, the production is nsnally achieved in a batch process over a heterogeneous catalyst at pressures of 5 to 35 bar and temperatures of 323 to 423 K. Nishimura [71] provides an excellent overview of the literature for the synthesis of primary, secondary, and tertiary amines via reductive alkylation. 

Keduction of alkyl halides. Alkyl halides are reduced readily to hydrocarbons by organosilanes under catalysis with aluminum chloride. This hydrocarbon synthesis is limited to alkyl halides that are not rearranged by the catalyst. Primary, secondary, and tertiary halides are reduced. Reduction with triethyl-... 

In conclusion, we have demonstrated the first example of Pd nanoparticles as a selective and recyclable catalyst for the alcoholysis of polyhydrosiloxane. Fair numbers of alcohols with diverse structures (primary, secondary, sterically bulky, and functionalized alcohols) were selectively and efficiently grafted onto the poly-siloxane backbone without any side reactions and under moderate reaction conditions. Additionally, active participation of Pd nanoclusters during the catalytic transformations was established by in situ EM analysis and controlled poisoning experiments. Moreover, a new approach for the synthesis and stabilization of Pd nanoclusters as a stable isolable powder and their redispersion in common solvents was presented. 

He J, Yamaguchi K, Mizuno N (2010) Selective synthesis of secondary amines via iV-aUcylation of primary amines and ammonia with alcohols by supported copper hydroxide catalysts. Chem Lett 39(11) 1182-1183... 

The eight kinds of catalysts may be roughly classified as protective catalysts and economic catalysts . Co-Mo hydrogenation catalyst and zinc oxide desulfurizer are the protective catalysts for the primary steam reforming catalysts. The high-temperature shift catalyst protects the low-temperature shift catalyst, and the methanation catalyst are the protective catalyst for ammonia synthesis catalyst. The catalysts for primary- and secondary-steam reforming, low-temperature shift and ammonia synthesis are responsible for the conversions of raw materials and the yield of products, and have direct effect on economic benefits of the whole plant, and are thus called as economic catalysts. The amount of catalysts used depends on the process and raw material. Table 1.2 represents the amount of the eight kinds of catalysts used in the different processes. The total volume of the catalysts is about 330 m in every plant, while there are only two kinds of catalysts with the volume of about 100-140 m when heavy oil or coal is used as raw material. Both shift... 

Wang et al. [53] have reported the synthesis of a new primary-secondary diamine catalyst containing a long alkyl chain and its application to the Michael addition of malonates to a,b-unsaturated ketones in water which was not successful earlier. This asymmetric Michael addition process was found to be effective... 

Chemical Properties. Trimethylpentanediol, with a primary and a secondary hydroxyl group, enters into reactions characteristic of other glycols. It reacts readily with various carboxyUc acids and diacids to form esters, diesters, and polyesters (40). Some organometaUic catalysts have proven satisfactory for these reactions, the most versatile being dibutyltin oxide. Several weak bases such as triethanolamine, potassium acetate, lithium acetate, and borax are effective as stabilizers for the glycol during synthesis (41). 

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