Search results
Results from the WOW.Com Content Network
The silicon effect also manifests in certain compound properties. Trimethylsilylmethylamine (Me 3 SiCH 2 NH 2) is a stronger base (conjugate pK a 10.96) than neopentylamine (conjugate pK a 10.21); trimethylsilylacetic acid (pKa 5.22) is a poorer acid than trimethylacetic acid (pKa 5.00). [1]
Negative hyperconjugation is seldom observed, though it can be most commonly observed when the σ *-orbital is located on certain C–F or C–O bonds. [ 3 ] [ 4 ] In negative hyperconjugation, the electron density flows in the opposite direction (from a π- or p-orbital to an empty σ * -orbital) than it does in the more common ...
The pK a of a compound is determined by many aspects, but the most significant is the stability of the conjugate base. This is primarily determined by the ability (or inability) of the conjugated base to stabilize negative charge. One of the most important ways of assessing a conjugate base's ability to distribute negative charge is using ...
Conjugate addition reactions of allylsilanes are possible, although unsaturated aldehydes undergo only 1,2 addition. [15] The combination of an allylsilane with an α,β-unsaturated ketone in the presence of a Lewis acid is known as the Sakurai reaction. The enolate intermediate that results from addition can be functionalized with a separate ...
Hyperconjugation can be used to rationalize a variety of chemical phenomena, including the anomeric effect, the gauche effect, the rotational barrier of ethane, the beta-silicon effect, the vibrational frequency of exocyclic carbonyl groups, and the relative stability of substituted carbocations and substituted carbon centred radicals, and the thermodynamic Zaitsev's rule for alkene stability.
instead of attached to Cl − anions and the conjugate bases will be weaker than water molecules. On the other hand, if a chemical is a weak acid its conjugate base will not necessarily be strong. Consider that ethanoate, the conjugate base of ethanoic acid, has a base splitting constant (Kb) of about 5.6 × 10 −10, making it a weak base. In ...
Silicon tetrachloride is manufactured on a huge scale as a precursor to the production of pure silicon, silicon dioxide, and some silicon esters. [11] The silicon tetrahalides hydrolyse readily in water, unlike the carbon tetrahalides, again because of the larger size of the silicon atom rendering it more open to nucleophilic attack and the ...
The silicon plays the key role in stabilizing the carbocation of carbon at the β-position. Hosomi-Sakurai reaction is also applicable for other functional groups such as enones, where conjugate addition is usually seen. In figure 2, the Hosomi- Sakurai reaction has been shown using a cinnamoyl ketone.