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Aldehydes and Ketones. Acyl Addition Reactions
Published in Michael B. Smith, A Q&A Approach to Organic Chemistry, 2020
A Grignard reagent is an organomagnesium compound, RMgX, formed by the reaction of magnesium metal with an alkyl halide (see Section 10.2). What characteristics of a Grignard reagent are pertinent to reactions with aldehydes or ketones?
Chemicals from Aromatic Hydrocarbons
Published in James G. Speight, Handbook of Petrochemical Processes, 2019
A Grignard reagent is a strong nucleophiles that can form new carbon–carbon bonds. In reactions involving Grignard reagents, it is important to exclude water and air, which rapidly destroy the reagent by protonolysis or oxidation. Since most Grignard reactions are conducted in anhydrous diethyl ether or tetrahydrofuran, side reactions with air are limited by the protective blanket provided by solvent vapors. Although the reagents still need to be dry, ultrasound can allow Grignard reagents to form in wet solvents by activating the magnesium such that it consumes the water.
Sonochemistry: A Versatile Approach
Published in Suresh C. Ameta, Rakshit Ameta, Garima Ameta, Sonochemistry, 2018
Grignard reagents are quite useful in organic synthesis. During conventional preparation of this reagent, one has to use the pure form of magnesium as well as distilled dry ether; whereas no prior treatment of magnesium is required and commercial sample of ether can also be used, if the reaction is carried out in the presence of ultrasound. A strong base such as lithium diisopropylamide can be obtained using lithium metal by ultrasonic exposure. This type of preparation is not possible otherwise.
Dispersion of graphene oxide and its application prospect in cement-based materials: a review
Published in Journal of Dispersion Science and Technology, 2023
Huangqi Wang, Liran Zhang, Dongmin Wang, Danhua Geng, Ming Zhang, Wenqian Du, Huixin Chen
Due to the high electronegativity of oxygen, the C = O and C–O–C electron clouds of carbonyl and epoxy groups, respectively, shift toward oxygen, causing a partial positive charge on C and making it the likely target for nucleophilic addition/substitution. Yuan et al.[74] used phenol and formaldehyde to react with epoxy groups on GO for functionalization and advance phenolic polycondensation to prepare GO-phenolic resin composites (Figure 7h). Collins et al.[75] used sodium malononitrile to react with epoxy groups to introduce nitrile groups on GO to improve GO dispersion and solubility. Grignard reagents are among the more important nucleophilic reactions for aldehyde/keto groups and epoxy groups. This reaction introduces a multitude of structures and contributes to GO functionalization. Huang et al.[76] reacted GO with Grignard reagent, such as C4H9MgCl (BuMgCl), to generate precursors for Ziegler–Natta polymerization (Figure 7j). Due to the selectivity of the special reaction, this type of reaction could introduce some functional groups into the special position in GO, which is an important method to stable functionalization of GO itself.