Order of reagent addition

As we described in Chapter 3, the binding of reversible inhibitors to enzymes is an equilibrium process that can be defined in terms of the common thermodynamic parameters of dissociation constant and free energy of binding. As with any binding reaction, the dissociation constant can only be measured accurately after equilibrium has been established fully measurements made prior to the full establishment of equilibrium will not reflect the true affinity of the complex. In Appendix 1 we review the basic principles and equations of biochemical kinetics. For reversible binding equilibrium the amount of complex formed over time is given by the equation 

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The hydrothermal synthesis system for secondary scale screening is based on multi-well-tumbled autoclaves modules [49]. Each module contains 16 PTFE vials each vial has an internal volume of 7 mL. The reactors can operate up to 200 °C. Many chemical and physical factors can affect the final hydrothermal synthesis outcome, making it a good application for high-throughput methods. In addition to the gel ingredients, these factors include the order of reagent addition, gel mix-... 

In order to avoid this possible side reaction and ensure its selectivity there was used either fast addition of alkyl halide or reversed order of reagent addition. The latter was used particularly with less active alkyl halides. 

Cyclopropenylium ions 1 were converted into the corresponding cyclopropenes 2 by the addition of hydride ion derived from various hydride sources, such as lithium aluminum hydride,sodium borohydride, borane-amine complex, triethylsilane, and tributyl-tin hydride. Particularly in the case of borohydride reduction of the diphenylcyclo-propenylium ion, the order of reagent addition was quite important. The slow addition of an acetonitrile solution of the cyclopropenylium salt into a solution of the borohydride gave the cyclopropene derivative,whereas the inverse order of addition resulted in quantitative formation of 1,2,4,5-tetraphenylbenzene (see Section 2.1.2.3.), No such precaution of the inverse addition was required in the case of borane-amine reduction of the l-chloro-2,3-diphenyl-cyclopropenylium ion. ... 

For most conetwork series, the copolymer composition and architecture were systematically varied by varying the comonomer feed compositions and by changing the order of reagent addition, respectively. Thus, end-linked conetworks based on ABA triblock copolymers of different composition, where usually the length of the mid-block remained constant and the length of the end-blocks was varied, were prepared. Architecture was usually varied at the equimolar composition to provide end-linked conetworks of the ABA triblock, the BAB triblock (prepared by reversing the order of monomer addition relative to the ABA triblock copolymer), and the statistical copolymer (two comonomers polymerized simultaneously) network. In addition to the end-linked conetworks, one randomly cross-linked network was also prepared by the simultaneous terpolymerization of the two comonomers and the cross-linker. This architecture is expected to be similar to... 

The method or order of reagent addition (e.g., adding catalyst to the initiator or initiator to the catalyst) can be crucial. 

In the synthesis of Ni(BME-DACH), does order of reagent addition matter (metal and ligand) Explain. 

Amemiya [28] has reported the use of electrochemical flow allylation, between allylic halides (33) and aldehydes (34) (Scheme 6.12) where in batch it is incredibly difficult to control whether the y-adduct (3S) or a-adduct (36) is obtained. The authors report that by altering the order of reagent addition and cathode material, chemoselective control over product formation can be achieved. Pt and Ag worked... 

The reaction is accomplished by adding a tetrahydrofuran solution of the first nucleoside to a lutidine solution of the rfiosphorylating agent, allowing the two to react for a short time and then adding a tetrahydrofuran solution of the second nucleoside. Only after comjdetion of the condensation is the oxidation undertaken by the addition of iodine crystals dissolved in water-tetrahydrofuran. This oxidation is also very quick. Of course this order of reagent addition will lead to formation of some unwanted (3 -> 3 )-and (5 5 )- isomer formation. For example, if two molecules of the first... 

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