Addition reaction mechanism

Additional Reaction Mechanisms. So far we have confined our discussion to the most common case of ester hydrolysis, that is, the case in which the reaction takes place at the carbonyl carbon. In some cases, however, an ester may also react in water by an SN-type or E-type mechanism (see Section 13.2) with the acid moiety (i.e., "OOC - R,) being the leaving group. The S -type reactions occur primarily with esters exhibiting a tertiary alcohol group. The products of this reaction are the same as the products of the common hydrolysis reaction. In the case of elimination, however, products are different since the ester is converted to the olefin and the corresponding conjugate base of the acid ... 

Iodo dimethyl amido complexes, with Ti(IV), 4, 331-332 Iodonium salts, cross-coupling with lead reagents, 9, 413 Ionic addition reactions, mechanisms, 1, 101 Ionic bis(isonitrile) complexes, liquid crystals, 12, 280 Ionic character, organometallic compound dn configuration,... 

As was the case for nucleophilic additions to aldehydes and ketones, two mechanisms occur for the reactions in this chapter one under basic conditions and one under acidic conditions. Both of these start in the same manner as the addition reaction mechanisms. The basic conditions mechanism is shown in Figure 19.1. First the nucleophile... 

Solid, higher-MW epoxy resins are often used for adhesive formulations that are applied as solids (e.g., film and powder) or a solvent solution. The higher-MW DGEBA resins are also used where improved toughness, flexibility, and adhesion are required. These resins have a greater number of hydroxyl groups along the chain and, thus, can provide better adhesion and additional reaction mechanisms. 

As a result of their properties, melamines are often used as decorative laminates. The melamine resins cure via an addition reaction mechanism so no reaction by-products can be produced on postcure as with the phenolic resins. The specific surface preparation for adhesive bonding and the preferred adhesives for bonding melamine and urea parts are similar to those suggested for phenolic resins. 

Acetylene terminated (AT) resins are being studied as a new technology to form the matrix of high performance structural composites (1). This class of resin cures by an addition reaction mechanism. Because of the absence of volatile by-product during cure, these resins are easy to process to yield void-free components. These resins also have the advantage over epoxy resins in terms of resistance to deterioration of properties at elevated temperature due to exposure to humid environments (2). 

The synthesis of 4 -thioxy loadcnosine 126, described in the pioneering work by Reist et has been improved" by direct glycosylation of V-benzoyladenine with the 1,4-dithio-D-xylofuranoside 123 in the presence of V-iodosuccinimide and catalytic triflic acid, followed by deprotection. Based on the ratio of isomers obtained (a -.ft 20 34) an iodium ion-promoted elimination-addition reaction mechanism has been proposed, as outlined in Scheme 35. 

Polyethylene, a very stable polymer used in packaging wraps, is made by joining ethylene monomers via an addition-reaction mechanism. First an initiator molecule (R2) is heated to produce two radicals ... 

Our UNDERSTANDING OF THE REACTIONS of popular reagents dates back to the early 1920s, when Lewis, Lowry, and Br nsted began developing their acid-base theories. Shortly thereafter, Lap worth, who had pioneered the study of carbonyl addition reaction mechanisms in the early 1900s, proposed the classification of polar reagents into the classes we know today as electrophiles and nucleophiles. 

Fig. 6.49 Rendering of acid-catalyzed addition reaction mechanism (a) and base-catalyzed (b) with the support of chemical ontological support system (COSS)...

General types of oxidative addition reaction mechanisms. 

Kim HS, Kurasawa Y, Yoshii C, Masuyama M, Takada A (1990b) Synthesis of pyirolo[l,2-a] quinoxalines by 1,3-dipolar cycloaddition reaction. An additional reaction mechanism via an aziridine intermediate. J Heterocyclic Chem 27(4) 1115-1117. doi 10.1002/jhet.5570270457 Kim HS, Nam SH, Kurasawa Y (1990c) A selective synthesis of isoxazolo[2,3-u]quinoxalines and pyrrolo[l,2-a]qiiinoxalines by 1,3-dipolar cycloaddition reaction. Taehan Hwahakhoe Chi 34 (5) 469-475. [CA 114, 101935 (1991)]... 

It is also possible to form polyamides through addition reaction mechanisms. For example, a major industrial process employs caprolactam as the starting material. This interesting substance can be induced to self-polymerize via addition as shown below ... 

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