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In addition to m-cymene, there are two other geometric isomers called o-cymene, in which the alkyl groups are ortho-substituted, and p-cymene, in which they are para-substituted. p-Cymene is the most common and only natural isomer. The three isomers form the group of cymenes. Cymenes can be produced by alkylation of toluene with propylene. [1] [2]
The body of the tables contain the characters in the respective irreducible representations for each respective symmetry operation, or set of symmetry operations. The symbol i used in the body of the table denotes the imaginary unit: i 2 = −1. Used in a column heading, it denotes the operation of inversion.
m- and p-Cymene are prepared by alkylation of toluene with propylene: CH 3 C 6 H 5 + 2 CH 3 CH=CH 2 → CH 3 C 6 H 4 CH(CH 3) 2. These alkylations are catalyzed by various Lewis acids, such as aluminium trichloride. m- and p-Cymene are mainly of interest as precursors to the respective cresols, which exploits the Hock rearrangements. [1]
Symmetrical examples include diphenylacetylene and 3-hexyne. They may also be asymmetrical, such as in 2-pentyne. Terminal alkynes have the formula RC≡CH, where at least one end of the alkyne is a hydrogen atom. An example is methylacetylene (propyne using IUPAC nomenclature). They are often prepared by alkylation of monosodium acetylide. [4]
Alkylation is the addition of alkyl groups to molecules, often by alkylating agents such as alkyl halides. Alkylating antineoplastic agents are a class of compounds that are used to treat cancer. In such case, the term alkyl is used loosely. For example, nitrogen mustards are well-known alkylating agents, but they are not simple hydrocarbons.
Friedel-Crafts alkylation: alkylbenzenes can be synthesized from olefins or alkyl halides with aromatic compounds in the presence of a catalyst such as AlCl 3, HF, or H 2 SO 4. [ 4 ] Gattermann-Koch reaction : named after German chemists Ludwig Gattermann and Julius Arnold Koch , the Gattermann-Koch reaction is a catalyzed formylation of ...
p-Xylene (para-xylene) is an aromatic hydrocarbon.It is one of the three isomers of dimethylbenzene known collectively as xylenes.The p-stands for para-, indicating that the two methyl groups in p-xylene occupy the diametrically opposite substituent positions 1 and 4.
In organic chemistry, alkynylation is an addition reaction in which a terminal alkyne (−C≡CH) is added to a carbonyl group (C=O) to form an α-alkynyl alcohol (R 2 C(−OH)−C≡C−R).