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Halogenation of benzene where X is the halogen, catalyst represents the catalyst (if needed) and HX represents the protonated base. A few types of aromatic compounds, such as phenol , will react without a catalyst , but for typical benzene derivatives with less reactive substrates, a Lewis acid is required as a catalyst .
Electrophilic aromatic substitution (S E Ar) is an organic reaction in which an atom that is attached to an aromatic system (usually hydrogen) is replaced by an electrophile. Some of the most important electrophilic aromatic substitutions are aromatic nitration , aromatic halogenation , aromatic sulfonation , alkylation Friedel–Crafts ...
The icosahedral charge-neutral closo-carboranes, 1,2-, 1,7-, and 1,12- C 2 B 10 H 12 (informally ortho-, meta-, and para-carborane) are particularly stable and are commercially available. [10] [11] The ortho-carborane forms first upon the reaction of decaborane and acetylene. It converts quantitatively to the meta-carborane upon heating in an ...
Alkylation of ortho-carborane at the 9 and 12 vertices via cross-coupling reaction with a palladium catalyst. Iodinated derivatives of carborane can be further modified to access boron alkylated products via a cross coupling reaction. This can be done by treating the halogenated carborane with a Grignard reagent in the presence of a phosphine ...
Halogenation of saturated hydrocarbons is a substitution reaction. The reaction typically involves free radical pathways. The regiochemistry of the halogenation of alkanes is largely determined by the relative weakness of the C–H bonds. This trend is reflected by the faster reaction at tertiary and secondary positions.
The cyclic compound borepin has been isolated and is aromatic. Boron-boron multiple bonds are rare, although doubly-bonded dianions have been known since the 1990s. [20] Neutral analogues use NHC adducts, such as the following diborane(2) derivative: [21] [22] Each boron atom has an attached proton and is coordinated to a NHC carbene. [23] [24]
In electrophilic substitution in aromatic compounds, an atom appended to the aromatic ring, usually hydrogen, is replaced by an electrophile. The most important reactions of this type that take place are aromatic nitration, aromatic halogenation, aromatic sulfonation and acylation and alkylating Friedel-Crafts reactions. It further consists of ...
Carborane acids H(CXB 11 Y 5 Z 6) (X, Y, Z = H, Alk, F, Cl, Br, CF 3) are a class of superacids, [1] some of which are estimated to be at least one million times stronger than 100% pure sulfuric acid in terms of their Hammett acidity function values (H 0 ≤ –18) and possess computed pK a values well below –20, establishing them as some of the strongest known Brønsted acids.