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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]
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]
In addition to p-cymene, two less common geometric isomers are o-cymene, in which the alkyl groups are ortho-substituted, and m-cymene, in which they are meta-substituted. p-Cymene is the only natural isomer, as expected from the terpene rule. All three isomers form the group of cymenes. Cymene is also produced by alkylation of toluene with ...
Thymol (also known as 2-isopropyl-5-methylphenol, IPMP), C 10 H 14 O, is a natural monoterpenoid phenol derivative of p-Cymene, isomeric with carvacrol.It occurs naturally in the oil of thyme, and it is extracted from Thymus vulgaris (common thyme), ajwain, [4] and various other plants as a white crystalline substance of a pleasant aromatic odor and strong antiseptic properties.
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 ...
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.
Antioxidants such as butylated hydroxytoluene (BHT) and butylated hydroxyanisole (BHA) are produced by Friedel-Crafts alkylation of phenols with isobutylene. tert-Butylamine is produced commercially by amination of isobutylene using zeolite catalysts: [6] NH 3 + CH 2 =C(CH 3) 2 → H 2 NC(CH 3) 3. Applications are found in the calibration 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.