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An aromatic ring can assist in the formation of a carbocationic intermediate called a phenonium ion by delocalising the positive charge. When the following tosylate reacts with acetic acid in solvolysis then rather than a simple S N 2 reaction forming B, a 48:48:4 mixture of A, B (which are enantiomers) and C+D was obtained [2] [3] .
In the periodic table of the elements, each column is a group. In chemistry, a group (also known as a family) [1] is a column of elements in the periodic table of the chemical elements. There are 18 numbered groups in the periodic table; the 14 f-block columns, between groups 2 and 3, are not numbered.
Group phenomena concern the behavior of a particular group of individual entities, usually organisms and most especially people. The behavior of individuals often changes in a group setting in various ways, and a group may have its own behaviors not possible for an individual because of the herd mentality .
Arranged this way, elements in the same group (column) have similar chemical and physical properties, reflecting the periodic law. For example, the halogens lie in the second-to-last group ( group 17 ) and share similar properties, such as high reactivity and the tendency to gain one electron to arrive at a noble-gas electronic configuration.
The f-block groups are ignored in this numbering. [22] Groups can also be named by their first element, e.g. the "scandium group" for group 3. [22] Previously, groups were known by Roman numerals. In the United States, the Roman numerals were followed by either an "A" if the group was in the s-or p-block, or a "B" if the group was in the d-block.
The acidity of the hydroxyl group in phenols is commonly intermediate between that of aliphatic alcohols and carboxylic acids (their pK a is usually between 10 and 12). Deprotonation of a phenol forms a corresponding negative phenolate ion or phenoxide ion , and the corresponding salts are called phenolates or phenoxides ( aryloxides according ...
The main group includes the elements (except hydrogen, which is sometimes not included [citation needed]) in groups 1 and 2 , and groups 13 to 18 . The s-block elements are primarily characterised by one main oxidation state, and the p-block elements, when they have multiple oxidation states, often have common oxidation states separated by two ...
In IUPAC nomenclature of chemistry, a pendant group (sometimes spelled pendent) or side group is a group of atoms attached to a backbone chain of a long molecule, usually a polymer. Pendant groups are different from pendant chains, as they are neither oligomeric nor polymeric. [2] For example, the phenyl groups are the pendant groups on a ...