Addition reactions product

The addition—reaction product of bisphenol A [80-05-07] and glycidyl methacrylate [106-91-2] is a compromise between epoxy and methacrylate resins (245). This BSI—GMA resin polymerizes through a free-radical induced covalent bonding of methacrylate rather than the epoxide reaction of epoxy resins (246). Mineral fillers coated with a silane coupling agent, which bond the powdered inorganic fillers chemically to the resin matrix, are incorporated into BSI—GMA monomer diluted with other methacrylate monomers to make it less viscous (245). A second monomer commonly used to make composites is urethane dimethacrylate [69766-88-7]. 

In alkaline solution, the phenol 1 is deprotonated to the phenolate 4, which reacts at the ort/zo-position with dichlorocarbene 3. The initial addition reaction product 5 isomerizes to the aromatic o-dichloromethyl phenolate 6, which under the reaction conditions is hydrolyzed to the o-formyl phenolate." ... 

Are Additional Reaction Products Formed during the Final Steps of Dehydration or during the Process of Paraff n Embedding What Is the Temperature Dependence of the Reactions that Lead to These Products ... 

Fig. 5. Addition reaction products from hexahydrophthalic anhydride and diisopropanol-amine rearrangement from AB2 to ABB monomer...

The formation of ammonia from the N-hydroxyethylethylenediamine during the reaction suggests that some additional reaction product is formed. From a consideration of the mechanism proposed, one would postulate that this reaction product is ethanolamine. Efforts to detect this compound were unsuccessful because of the large concentration of N-hydroxy ethylethylenediamine. 

TiC is thermodynamically not compatible with Si3N4 under sintering conditions. TiC reacts with Si3N4 forming TiCxN x where the x values are in the range of 0.3 [568, 569] to 0.24 [567], The x value in TiCxN x depends on nitrogen pressure and temperature. As an additional reaction product, SiC may be formed or the oxide nitride liquid phase can be reduced by carbon... 

Insertion and Addition Reaction Products of Arynes with Pyridine... 

In some electrophilic addition reactions, products from carbocation rearrangements are formed. 

Interestingly, Tbt-substitued metallabenzenes and 1-silanaphthalene were found to undergo 1,2- and/or 1,4-addition reactions depending on the character of the reactants, whUe Tbt-substituted 2-metallanaphthalenes afforded only 1,2-addition reaction products. The remarkable reactivity of the metallaaromatic species towards addition reactions implies that their aromatic stabilization energies are insufficient to suppress the inherent high reactivity of the M=C bonds (M = Si, Ge). 

One of the functions of mechanical abrasion is to break up these boundary layers and assist in the transport of reactants to and products from the surface. During polishing, abrasive particles penetrate through the boundary layers bringing fresh chemical reactants to the surface. Chemical reactants may be adsorbed onto the abrasive or simply be able to diffuse to the surface more readily by virtue of the disruption of the boundary layers. In addition, reaction products can adsorb onto the abrasive particle to be transported from the surface with the particle (see, for example, Section 5.1.3). By assisting in the transport of reactants and products, abrasion serves to accelerate the chemical component of CMP as well as providing the mechanical component. 

In addition, reaction products display in most cases the clues one needs to explain their mechanism of formation. The problem then becomes how to identify those magic features. For this purpose fragmentation analysis is positively the method of choice. 

An alternative "after combustion" type of CO2 removal is to convert atmospheric CO2 to methanol by a catalytic process at elevated temperature and pressure. Catalyst based on Cu and ZnO are used and laboratory demonstrations performed at a temperature of 150°C and a pressure of 5 MPa (Saito et al., 1997). Additional reaction products are CO and water. Other... 

Since products from the 1,6-addition reactions are formed in much larger amounts than those from the 1,2-addition reaction (38 72), and since no cyclization takes place in the latter reaction, the conclusion was made that the 1,2-addition reaction product results from a collapse of a radical anion (ketyl)-radical cation (RMgX pair in which the group R of the Grignard is still tightly bound to the magnesium. 

However, how free, is the radical anion in reactions of benzophenone In the presence of a radical anion scavenger, such as p-dinitrobenzene [48], pinacol formation is totally suppressed in reactions of CHjMgBr and f-C4H9MgCl [49] with 2-methylbenzophenone, but the same scavenger had no effect on the ratio or the rate of 1,2- and 1,6-addition reaction products. Thus, the formation of these products does not involve a free ketyl. A single-electron transfer (SET) intermediate, I, was proposed (Scheme 12)... 

The SET intermediate I could either directly form a 1,2-addition reaction product (see Scheme 13 path a no isomerization) or it could dissociate to form a radical anion and a free radical within the solvent cage. Collapse of the two radicals leads to the formation of the 1,6-addition reaction products, whereas escape from the solvent cage would lead to radical reaction products, such as benzopinacol and R- H, the result of solvent attack (Scheme 13) ... 

The larger amounts of Grignard reagents, compared with ketones, lead to the formation of greater amounts of addition reaction products. 

The reaction of 1 molEq of n-propylmagnesium bromide with 1 molEq of diisopropyl ketone, a sterically crowded ketone, gave the normal addition reaction product in only low yields the major product of the reaction was the reduction reaction product, formed by the transfer of a /-hydrogen from the Grignard reagent to the ketone. Owing to an enolization reaction (Scheme 21), 3% unreacted ketone could be isolated ... 

Such a mechanism predicts that one should be able to increase the yield of the addition reaction product to a hindered ketone at the expense of reduction by the simple expedient of adding magnesium bromide to the ketone before addition of the Grignard reagent. 

The mechanisms of reactions of benzylmagnesium halides can be either homolytic or concerted. As with allylic Grignard reagents, also reversible addition reactions with benzylic Grignard reagents and carbonyl compounds have been reported. In general, yields of normal alcohols are low, and such alcohols are obtained in much better yields by use of dibenzylcadmium [66] or benzyllithium [67]. However, in 1980, it was demonstrated that, by far, the best and quickest results for the synthesis of these normal addition reaction products are obtained by applying benzylic halides in the one-step Li-Barbier reaction under ultrasonic irradiation [68,69]. 

The low yield of addition reaction product, obtained with the neopentyl Grignard reagent is most likely due to the bulkiness of this reagent (see Section II.A.l). Although... 

Primary and secondary Grignard reagents all gave addition reaction products in yields between 10 and 20%, but the rates of reaction increased by a factor of 10 for each hydrogen in the -position. Table 5 presents some of the results obtained. A six-center transition state seems indicated in which the -hydrogen atom is very close to an azo-nitrogen. Comparison of the results obtained with benzophenone as the substrate did not lead to satisfactory answers for the exact mechanisms involved. 

Apart from these SET reactions, solvent effects in reactions of organomagnesium reagents with carbonyl compounds have been studied rather extensively. The reaction of ethylmagnesium bromide with benzophenone (Scheme 15) in diethyl ether yields 94% of the expected addition reaction product, 1,1-diphenyl-1-propanol, and 6% benzhydrol, resulting from a reduction reaction of the Grignard reagent [36]. In tetrahydrofuran this reaction yields 21 and 77%. respectively, of both products. 

It was found that some organic solid-solid reactions proceed very efficiently and selectively in the presence of a small amount of solvent vapor. For example, when a solution of 34 and 35 in MeOH was kept at room temperature for 1 h, the Michael addition reaction product 36 was obtained in 71% yield (Table 2.2.2) [19]. In contrast, the reaction in the solid state gave 36 in a poor yield. Heating a mixture of 34 and 35 at 100 °C for 4h gave 36 in only 21% yield. However, when the reaction was carried out at room temperature in the presence of MeOH vapor for 1 h, the result was 36 in 63 % yield. By prolongation of the reaction to 2 and 4 h, the yield increased to 81 and 90%, respectively. The efficiency of these reactions under MeOH vapor is much better than that of the same solid-solid reaction and the solution reaction in MeOH (Table 2.2.2). 

S.2.2.4. Triazoles from Azides. Cycloadditions of this type constitute a valuable synthetic route to the triazole ring system. This is shown in Scheme 5.30. This combination dates back to the early work of Huis-gen, but in more recent times it was discovered to be subject to catalysis by Cu(I) compounds. The reactions are fast under mild conditions, have high regiospecificity, and occur in a variety of solvents including water. In addition, reaction products are easily isolated. Reactions with these characteristics have become known as comprising click chemistry this term was coined by K. B. Sharpless. The first and most commonly used reaction referred to by this name is indeed the azide-alkyne cycloaddition, and new interest has developed in triazole hemistry since the discoveiy of the copper catalysis. In addition to its use in organic... 

Polyalkenamer n. A chlorine-containing elastomer developed by Goodyear, with properties similar to but somewhat better than those of neoprene rubber. It is a co-polymer of the addition-reaction product of hexachlorocyclo-pentadiene or 1,5-cyclooctadiene and an olefin such as cyclopentane. 

The addition-reaction product of bisphenol A and glycidyl methacrylate or an epoxy resin and methacrylic acid is bis-GMA 2,2- 7Z5 4-(2-hydroxy-3-methacryloxypropoxy)phenyl propane (Fig. 5). Bis-GMA can therefore be classified as a dimethacrylated epoxy, although it does not contain a reactive epoxy group. Bis-GMA is the most commonly used prepolymer in dental composite restorative materials. Several similar compounds have also appeared as substitutes for Bis-GMA or in addition to it in dental resins. Such dimethacrylates based on bisphenol A with various chain lengths are bis-MA 2,2- fs(4-(metha-cryloxy)phenyl)-propane, bis-EMA 2,2-i7is(4-(2-met-hacryloxyethoxy)phenyl)-propane and bis-PMA 2,2- s(4-(3-methacryloxypropoxy)phenyl)-propane. 

Lithioadamantane, formed by reaction of 1-bromo- or 1-chloroadaman-tane (1-AdBr or 1-AdCl) with lithium in diethyl ether at — 20 °C, yielded 75% 1-Ad-D on deuterolysis. Addition of hexamethylacetone (HMA) to the reaction mixture yielded virtually no carbonyl addition reaction product. 

---