Us5015786a preparation of cumene through alkylation of an. However, phenol esters also undergo a fries rearrangement under friedelcrafts conditions to produce the calkylated, hydroxyarylketones. A method of alkylating a phenol is disclosed which comprises contacting a phenol having a hydrogen atom in at least one of the orthopositions relative to the hydroxyl group with an alcohol in the gaseous phase at an elevated temperature in the presence of a catalyst comprising iron oxide, silica, chromium oxide, germanium oxide and an alkali metal compound. Alkylation of phenolic compounds with olefins is an important industrial reaction to increase the chemical stability of biooil. The possibility of product 1 being formed is higher than the probability of formation of product 2. Crafts, the reaction of an alkyl halide with an aromatic compound in the presence of a lewis acid catalyst, usually alcl 3, results in the substitution of the alkyl group onto the aromatic ring. As the catalyst acidity increases, 2,6 xylenol and trimethylphenol selectivity increases. Chem 1650 phenol alkylation phenol alkylation abigail. Alkylation of phenol with tertbutyl alcohol catalysed by. As the title suggests im trying to alkylate a phenol, with a propargyl group. The friedelcrafts alkylation of phenol is an equilibri openi. The kinetic parameters such as rate constant k, apparent activation energy ea and arrhenius frequency factor ao for the disappearance of phenol were. Model liquid phase reactions of 1octene with phenol, catechol and guaiacol, respectively, were carried out over acid catalyst 30%cs2. Alkylation of phenol has an additional complication because of the possibility of the olefin attack to the phenolic oxygen o alkylation leading to ether formation beside the usual alkylation at the aromatic ring c alkylation.
C alkylation can also be effected by alkenes in the presence of acids. In opposite vapour phase alkylation is simplest and. The true value of altud1 is revealed in the friedelcrafts alkylation of phenol. Synthesis of aryl alkyl ethers by alkylation of phenols with quaternary ammonium salts.
In most cases the electrophile is the carbocation that is generated when the halide acts. Abstract o or nalkylated derivatives of aminophenols are important synthetic intermediates in organic synthesis. Alkylation of phenol materials and process simulation center. The regioselectivity of an alkylation with long chain olefin is really difficult to control, specifically, in the case of benzene alkylation, where there is now an increasing need to preferentially generate the more desirable 2 phenyl alkylate flch3 in equation 2 in scheme1 and to avoid the formation of nonlinear alkylbenzene. Alkylation of phenol with hexene1 in the presence of 94% sulphuric acid temperatur e 140 c, time of addition 2h, time of stirring. Oalkylation of phenol in the presence of a nucleophilic. Abstract intramolecular dearomative cyclization of phenols with. Hence a sequence of alkylation and dealkylation steps are possible through out the reaction. Synthesis of aryl alkyl ethers by alkylation of phenols with. My molecule has 2 nucleophilic centres present, the phenol and a tertiary amine, and i want o alkylation.
The mechanism for this reaction begins with the generation of a methyl carbocation from methylbromide. In particular, monosubstituted 1,3diketones 17 and their derivatives are of great interest. O alkylation of phenol in the presence of a nucleophilic tertiary amine. Alkylation of benzene with isopropanol on mixed oxides7 and benzoylation of toluene over different sulphated zirconia and iron incorporated sulphated zi rconia systems8 have been reported. Pdf alkylation of phenol with olefins in the presence of. In a first form, a process is provided for preparing phenol by converting acetone byproduced by the cumene process into isopropanol, and alkylating benzene with the isopropanol and optional propylene, thereby forming phenol without acetone byproduct. The main purpose of using alcl3 is to polarise the halo alkane bondalkylation. C alkylation is a process for the formation of carboncarbon bonds. This reaction is popularly known as reimertiemann reaction. However, no significant improvement was observed in the yield of the monoderivative, which in some cases is the desired product. Alkylation of phenol with methanol over mixed oxides of tin. In the case of phenol, oalkylation with ethyl methyl carbonate proceeds in the. Aqueousmediated nalkylation of amines full paper but the reaction rate is slow and it requires a longer reaction time 810 h.
Lewis acids are particularly suited for c alkylation. Given that the alkylation typically requires stoichiometric amounts of a base and a toxic alkyl halide the devel. The reaction when carried out in the liquid phase give numerous products and their separation is difficult. Tandem esterification1,4additiontype friedelcrafts alkylation. Acidcatalyzed liquidphase alkylation of phenol with. Usually in the gas phase vapours of methanol and phenol are reacted in a flow reactor under atmospheric pressure and most frequently in the temperature range 583 0166. Some of the existing aqueous alkylation procedures are not successful because of the rapid hydrolysis of the alkylbenzylic halides under strongly basic conditions csoh, naoh, k 2co 3 koh, etc. Ethylation, diethyl carbonate, phenols, aryl ethyl ethers. From the above discussion it is clear that product selectivity in the alkylation of phenol with methanol depends mainly on the acidbase properties of the catalysts. Do phenols undergo friedel crafts alkylation reaction when. A simple method for chemoselective phenol alkylation request pdf. An alkyl group can be added to a benzene molecule by an electrophile aromatic substitution reaction called the friedel. Industrially the phenol methylation is carried out by means of three types of processes.
Isobutane and c 3 c 4 olefins are produced as byproducts from fcc and other catalytic and. Study of the reaction mechanism in the alkylation of. Electrophilic substitution reactions of phenols nitration. Alkylation definition of alkylation by the free dictionary. For detailed discussions on electrophilic substitution reactions of phenols, please visit byjus. Alkylation of phenol by myrtenol in the presence of aluminum phenoxide and aluminum isopropoxide was studied in the temperature range 120160c. Pioneering reports dealing with the nalkylation of amines by alcohols in the presence of homogeneous catalysts were described independently by watanabe 14 and grigg 15. The alkylation of carboxylic acids with alcohols in acidic.
Friedelcrafts reaction of phenol chemistry stack exchange. The main purpose of using alcl3 is to polarise the halo alkane bond alkylation. The catalyst is modeled with the benzene sulfonic acid, and the effect of this acid on olefins such as isopropene ipr and tributene tbu in a phenol solution mimics. Efficient and selective n alkylation of amines with. Alkylation of phenol with mtbe and other tertbutyl ethers. The reaction occurred with the formation of an array of alkylated phenols. Synthesis of 2,6xylenol by alkylation of phenol with. However, 100% selectivity towards methylation was not obtained. Page 293 selective alkylation of aminophenols renchao wang and jiaxi xu state key laboratory of chemical resource engineering, and department of organic chemistry, faculty of science, beijing university of chemical technology, beijing 100 029, china email. Ep0419045a1 method for alkylation of phenols, and catalyst. Realization of the o alkylation process using simple phenolic.
Alkylation of phenol provides many industrial intermediates such as agrochemicals and polymers. Realization of the oalkylation process using simple phenolic. The alkylation process combines light isoparaffins, most commonly isobutane, with c 3 c 4 olefins, to produce a mixture of higher molecular weight isoparaffins i. Alkylation of phenols with isobutylene publications of the. The longchain alkylphenols are prepared by alkylation of phenol with alkenes. Mechanistic aspects of alkylation of a general carboxylic acid. Apr 09, 2011 the product 1 is formed by the o alkylation of the phenolate anion, while product 2 is formed via c alkylation of the phenolate anion. Alkylation of phenol with other alkenes and cresols alkylations were successfully catalysed by. So when we add this reactant mixture to the substrate which is phenol. Mass transfer influenced the rate of alkylation of phenol and pcresol with isobutylene in a bubble column. Our calculations conclude that o alkylation to form the phenolic ether is the most energetically favorable in the neutral condition.
Isobutylene is commercially produced mostly from the dehydration of tert butyl alcohol or from the cracking of methyl tertbutyl ether mtbe. One example is the addition of a methyl group to a benzene ring. The alkylation of phenol with alcohols and olefins is an important process used in industrial scale. This may sometimes lead to unexpected products under thermodynamic control conditions such as prolonged reaction times or at high temperatures.
Phenol alkylation abigail sanders anna katherine edmondson introduction. Isomerization of the terpene substituent as a result of rearrangements of the bicyclic myrtenol structure was observed. Friedelcrafts alkylation reactions of phenolsnaphthols with. However, under certain conditions, it is possible to form product 2 as well. Dimethyl carbonate and phenols to alkyl aryl ethers synthesis. Selective alkylation of phenols using solid catalysts white rose. The purpose of this experiment was to conduct a substitution reaction which can be used to construct from two sample parts.
This is an example of the synthesis of the reaction. For alkylation at carbon, the electrophilicity of alkyl halides is enhanced by the presence of a lewis acid such as aluminium trichloride. When phenol is treated with chloroform in the presence of sodium hydroxide, an aldehyde group is formed at the ortho position of the benzene ring. Structure and reaction mechanism of alkylation of phenol with. The mechanism involves an exothermic reaction between olefin and the benzene sulfonic acid to form ester followed by three reaction pathways leading to direct. A phenol derivative, phenolphthalein is prepared by the reaction of phenol with phthalic. Alkylation of phenol was carried out using methyl tertbutyl ether, mono tertbutyl ether of mono ethylene glycol, tertbutanol and. Alkylated phenols are widely used as additives in gasoline, lubricants and surfactants.
Phenolic compounds can be efficiently omethylated with tetramethylammonium chloride in diglyme or polyethyleneglycol peg at temperatures of 150160 c and in the presence of either k2co3 or naoh. Feb 16, 2006 the mechanism involves an exothermic reaction between olefin and the benzene sulfonic acid to form ester followed by three reaction pathways leading to direct o alkylation, oc alkylation, and pc alkylation. Chapter 3 friedelcrafts alkylation of phenol using ionic. In this study, the liquidphase alkylation of phenol with linear 1octene and branched diisobutylene olefins was studied, in a batch reactor using homogeneous sulfuric acid and heterogeneous amberlyst15 acid catalysts. Liquid phase alkylation of anisole and phenol catalyzed by.
606 1495 1535 104 1457 1208 267 532 161 820 1199 573 1242 1241 959 442 744 1518 1034 1462 634 91 1072 358 1376 501 1002 907 442 1397 162 537 1001 1053 890 158