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In the case of alkenes, this is due to isomerization of the monomer double bond; for heterocycles, this is due to release of monomer ring strain and, in some cases, isomerization of repeating units. Monomers for cationic polymerization are nucleophilic and form a stable cation upon polymerization.
Anti addition is in direct contrast to syn addition. In anti addition, two substituents are added to opposite sides (or faces) of a double bond or triple bond, once again resulting in a decrease in bond order and increase in number of substituents. The classical example of this is bromination (any halogenation) of alkenes. [5]
Dihydroxylation is the process by which an alkene is converted into a vicinal diol.Although there are many routes to accomplish this oxidation, the most common and direct processes use a high-oxidation-state transition metal (typically osmium or manganese).
The following is the reaction mechanism of a nucleophilic aromatic substitution of 2,4-dinitrochlorobenzene (1) in a basic solution in water. Nucleophilic aromatic substitution Since the nitro group is an activator toward nucleophilic substitution, and a meta director, it is able to stabilize the additional electron density (via resonance) when ...
Substitution reactions in organic chemistry are classified either as electrophilic or nucleophilic depending upon the reagent involved, whether a reactive intermediate involved in the reaction is a carbocation, a carbanion or a free radical, and whether the substrate is aliphatic or aromatic. Detailed understanding of a reaction type helps to ...
Step-growth polymers increase in molecular weight at a very slow rate at lower conversions and reach moderately high molecular weights only at very high conversion (i.e., >95%). Solid state polymerization to afford polyamides (e.g., nylons) is an example of step-growth polymerization. [8]
A hydrogen on the α position of a carbonyl compound is weakly acidic and can be removed by a strong base to yield an enolate ion. In comparing acetone (pK a = 19.3) with ethane (pK a = 60), for instance, the presence of a neighboring carbonyl group increases the acidity of the ketone over the alkane by a factor of 10 40.
The same is true when an alkene reacts with water in an additional reaction to form an alcohol that involves carbocation formation. The hydroxyl group (OH) bonds to the carbon that has the greater number of carbon-carbon bonds, while the hydrogen bonds to the carbon on the other end of the double bond, that has more carbon–hydrogen bonds.