Structure-reactivity relationships in organosilicon chemistry revisited

Abstract

Abstract:© Versita Sp. z o.o. Keywords: Correlation analysis • Linear free energy relationships • Silicon compounds • Substituent effectsAvailable quantitative data of the reactivity of organosilicon compounds were subjected to correlation analysis. As an alternative to the carbon chemistry values, the scale of steric constants E S (Si) can be used for organosilicon compounds and the inductive effect is best expressed by two terms, involving the parameter of electronegativity of substituents. Alkyl substituents contribute to the reactivity exclusively through their steric effects, steric and polar effects in silicon compounds are additive and the resonance effect is insignificant. The correlation analysis can be employed in investigations of organosilicon reactions along with other methods.

(NHC)Ni(0)-Catalyzed Branched-Selective Alkene Hydrosilylation with Secondary and Tertiary Silanes

“…Expansion to tertiary (3°) silanes has been a recent focus due to the relevance in industrial hydrosilylation, and particularly important advances have been made using alkoxy-substituted silanes to form the linear hydrosilylation products with exceptional regioselectivity. ,,,,,,,,,,, Despite these advances, most reports focus on 1 and 2° aryl silanes, emphasizing the need to develop catalysts that enable the hydrosilylation of 3° silanes, especially chloro- and alkoxy-substituted silanes (Figure b). Notably, only a handful of base-metal catalysts have been developed to react with chlorosilanes, and all of them either give poor selectivity or have limited scopes. ,,− Indeed, investigation and expansion of the silane scope are often neglected in hydrosilylation reactions, despite the fact that changes in both the silane’s electronic − and steric ,− characteristics impact reactivity and properties of hydrosilylation products.…”

The Influence of Silane Steric Bulk on the Formation and Dynamic Behavior of Silyl Palladium Hydrides

“…In addition to electronic factors, the steric profile of silanes plays an important role in their reactivity and properties, from synthetic reactions to material properties (Figure b). , For example, the properties of polysiloxane polymers can be tuned by the modification of the steric bulk of the sidechains at silicon, − and the aggregration behavior of siloxane-based surfactants is heavily affected by steric effects at silicon. − Late-stage modification of polysiloxanes and polybutadiene by transition metal-catalyzed hydrosilylation is hindered by sterically large substituents at silicon. − …”

A Kinetic View of the Mechanism of the Grignard Reaction with Alkoxysilanes

“…The enhanced Likewise, the additivity of steric effects was obvious, thus corroborating earlier conclusions drawn from results for alkyl substituents. 23,26 From the δ values in Table 2, an interrelation between the reaction mechanism and the steric effect is evident. For instance, it is obvious that the Grignard reaction with alkoxysilanes (series 1-3) is more susceptible to the steric effects than are chlorosilanes, which is consistent with the early transition state for the reaction of chlorosilanes, which possess a good leaving group.…”

“…In addition, the results reaffirm that alkyl substituents contribute to the reactivity exclusively with steric effects. [25][26][27] Additionally, the interrelation between the steric factor and the bulkiness of both Grignard reagents is evident.…”