Three reaction steps

PO—SM Coproduction. The copioduction of propylene oxide and styrene (40—49) includes three reaction steps (/) oxidation of ethylbenzene to ethylbenzene hydroperoxide, (2) epoxidation of ethylbenzene hydroperoxide with propylene to form a-phenylethanol and propylene oxide, and (3) dehydration of a-phenylethanol to styrene. 

From the three reaction steps cited above the overall reaction is ... 

In three reaction steps the ditosylate 29 leads to the bistosylate of the mono-spiro[3.3]heptane 32, which can be converted in successive iteration steps to polyspiranes of any length. Starting from the tetratosylate of the cyclobutane compound 33 the application of two iterative reaction sequences at the same time is possible. Nonaspiro compound 34 was thus synthesized in only twelve reaction steps [56]. 

The basic energy source in young stars is the fusion of protons into the 4He nucleus in three steps. This process is occurring in our Sun and other main-sequence stars where it produces about 91 per cent of the total energy. The proton-proton cycle proceeds via three reaction steps ... 

These chemical equations may be combined indefinitely to form other equivalent sets of three equations. They do not necessarily represent chemical reactions in a reaction network. The network deduced from kinetics results by Spencer and Pereira (see Example 5-8) involved (3), (1)—(3), and (2) as three reaction steps. 

Molten sodium tetrachloroaluminate (a 1 1 mixture of NaCl and AICI3) is a good reaction medium for the Friedel-Crafts acylation reaction given in fig. 3.3 (Wade et al., 1979). Whereas the classical procedure for the synthesis of 1-indane from 3-phenylpropanoic acid consists of three reaction steps with a total reaction time of ca. six hours (Gattermann et al., 1982), the molten salt reaction is finished in five minutes and gives an even better yield (Wade et al., 1979). 

TABLE 1. Selected Spirobifluorene Monomers Prepared in Three Reaction Steps for Subsequent Conversion into Spirobifluorene Copolymer by Yamamato Coupling... 

The catalyst must activate three reaction steps Dehydrogenadon of the alcohol, condensation of the aniline with the carbonyl compound produced and hydrogenation of the resulting imine to the desired N-alkylaniline. In the vapor phase the hydrogenation step is the most difficult to achieve under our reaction conditions. 

From our results we conclude that doubly-promoted Pt-Si02 catalysts are useful for the N-alkylation of hindered anilines in the gas phase. In most cases studied the addition of a promoting metal is necessary in order to get high activities and selectivities. If the silica does not contain enough basic trace metals, a second promotor has to be added. Because three reaction steps must occur on the same catalyst, the individual effects of the promoting metals are not easy to explain. In most cases the hydrogenation activity is the crucial parameter. Because the properties of the catalyst can be influenced by the choice of the promotors, they can be optimized for different substrates. 

The Reduction Reactions. The object of the next three reactions (steps 4 to 6 in fig. 18.12a) is to reduce the 3-carbonyl group to a methylene group. The carbonyl is first reduced to a hydroxyl by 3-ketoacyl-ACP reductase. Next, the hydroxyl is removed by a dehydration reaction catalyzed by 3-hydroxyacyl-ACP dehydrase with the formation of a trans double bond. This double bond is reduced by NADPH catalyzed by 2,3-trans-enoyl-ACP reductase. Chemically, these reactions are nearly the same as the reverse of three steps in the j6-oxidation pathway except that the hydroxyl group is in the D-configuration for fatty acid synthesis and in the L-configuration for /3 oxidation (compare figs. 18.4a and 18.12a). Also remember that different cofactors, enzymes and cellular compartments are used in the reactions of fatty acid biosynthesis and degradation. 

Choose one of the 3D Models of amine bases in eChapter 24.12, and draw the structural formula. Use the structure you have drawn along with the sugar ribose to write out the first three reaction steps represented in the Nucleic Acid activity to demonstrate the formation a nucleotide. 

This reaction is particularly suitable for the preparation of the Wieland-Miescher ketone 96, a very useful building block for construction of a broad variety of biologically active compounds such as steroids, terpenoids, and taxol. On the basis of the proline-catalyzed approach described above Barbas et al. recently reported an optimized procedure for formation of the chiral Wieland-Miescher ketone, 96 [105]. It has been shown that this synthesis (which comprises three reactions) can be performed as a one-pot synthesis. The desired product is obtained in 49% yield with enantioselectivity of 76% ee (Scheme 6.43). Here L-proline functions as an efficient catalyst for all three reaction steps (Michael-addition, cydiza-tion, dehydration). It is also worth noting that although many other amino adds and derivatives thereof were tested as potential alternative catalysts, L-proline had the best catalytic properties for synthesis of 96. This result emphasizes the superior catalytic properties of proline reported after previous comparative studies by the Hajos group [100, 101]. 

The model used for this analysis comprises three reaction steps interconnecting four reactants, A, X, Y, and B. 

Whereas the classical procedure for the synthesis of 1-indanone from 3-phenylpropanoic acid consists of three reaction steps with a total reaction time of ca. six hours [116], the molten salt reaction is finished in five minutes and gives an even better yield [115]. 

When heterogeneous reactions are carried out at steady state, the rates of each of the three reaction steps in series (adsorption, surface reaction, and desorption) are equal to one another ... 

The three reaction steps are based on very different physical chemical relationships which appreciably influence the operation of the process. The third step is normally followed by tail gas purification, to prevent the emission of nitrous gases. 

Equation (5) can be divided into three reaction steps ... 

Once again, the best catalyst turns out to be (promoted) Pt. Roughly speaking, three reaction steps can be distinguished in the electrochemical oxidation of MeOH over Pt ... 

MIBK is produced from acetone and H2 in three reaction steps (Figure 2.40). In the conventional process, the first step is the self-condensation of acetone to diacetone... 

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