Isomerization aluminum chloride

In an attempt to prepare propylbenzene a chemist alkylated benzene with 1 chloropropane and aluminum chloride However two isomeric hydrocarbons were obtained m a ratio of 2 1 the desired propylbenzene being the minor component What do you think was the major product How did it anse ... 

When 2 isopropyl 13 5 tnmethylbenzene is heated with aluminum chloride (trace of HCl present) at 50°C the major material present after 4 h is 1 isopropyl 2 4 5 tnmethylbenzene Sug gest a reasonable mechanism for this isomerization... 

The preference for O acylation of phenols arises because these reactions are kmetically controlled O acylation is faster than C acylation The C acyl isomers are more stable how ever and it is known that aluminum chloride is a very effective catalyst for the conversion of aryl esters to aryl ketones This isomerization is called the Fries rearrangement... 

Isopropylnaphthalenes can be prepared readily by the catalytic alkylation of naphthalene with propjiene. 2-lsopropylnaphthalene [2027-17-0] is an important intermediate used in the manufacture of 2-naphthol (see Naphthalenederivatives). The alkylation of naphthalene with propjiene, preferably in an inert solvent at 40—100°C with an aluminum chloride, hydrogen fluoride, or boron trifluoride—phosphoric acid catalyst, gives 90—95% wt % 2-isopropylnaphthalene however, a considerable amount of polyalkylate also is produced. Preferably, the propylation of naphthalene is carried out in the vapor phase in a continuous manner, over a phosphoric acid on kieselguhr catalyst under pressure at ca 220—250°C. The alkylate, which is low in di- and polyisopropylnaphthalenes, then is isomerized by recycling over the same catalyst at 240°C or by using aluminum chloride catalyst at 80°C. After distillation, a product containing >90 wt % 2-isopropylnaphthalene is obtained (47). 

Initially, aluminum chloride was the catalyst used to isomerize butane, pentane, and hexane. Siace then, supported metal catalysts have been developed for use ia high temperature processes that operate at 370—480°C and 2070—5170 kPa (300—750 psi), whereas aluminum chloride and hydrogen chloride are universally used for the low temperature processes. 

Ethyltoluene is manufactured by aluminum chloride-cataly2ed alkylation similar to that used for ethylbenzene production. All three isomers are formed. A typical analysis of the reactor effluent is shown in Table 9. After the unconverted toluene and light by-products are removed, the mixture of ethyltoluene isomers and polyethyltoluenes is fractionated to recover the meta and para isomers (bp 161.3 and 162.0°C, respectively) as the overhead product, which typically contains 0.2% or less ortho isomer (bp 165.1°C). This isomer separation is difficult but essential because (9-ethyltoluene undergoes ring closure to form indan and indene in the subsequent dehydrogenation process. These compounds are even more difficult to remove from vinyltoluene, and their presence in the monomer results in inferior polymers. The o-ethyltoluene and polyethyltoluenes are recovered and recycled to the reactor for isomerization and transalkylation to produce more ethyltoluenes. Fina uses a zeoHte-catalyzed vapor-phase alkylation process to produce ethyltoluenes. 

The demand for aviation gasoline during World War II was so great that isobutanc from alkylation feedstock was insufficient. This deficiency was remedied by isomerization of abundant normal butane into isobutane using the isomerization catalyst aluminum chloride on alumina promoted by hydrogen chloride gas. 

The method described above may be used for the preparation of a wide variety of butenolides substituted in the arylidene ring with either electron-withdrawing or electron-releasing substituents. y-Lactones such as a-benzylidene-7-phenyl-A 1 -bu-tenolide are isoelectronic with azlactones, but have received much less attention. Like the azlactone ring, the butenolide ring may be opened readily by water, alcohols, or amines to form keto acids, keto esters, or keto amides.7 a,-Benzylidene-7-phenyl-A3,1 -butenolide is smoothly isomerized by aluminum chloride to 4-phenyl-2-naphthoic acid in 65-75% yield via intramolecular alkylation. 

Allylmagnesium bromide, 41, 49 reaction with acrolein, 41, 49 5-Allyl-l,2,3,4,5-pentachlorocyclopen-tadiene, 43, 92 Allyltriphenyltin, 41, 31 reaction with phenyllithium, 41, 30 Aluminum chloride, as catalyst, for isomerization, 42, 9 for nuclear bromination and chlorination of aromatic aldehydes and ketones, 40, 9 as Friedel-Crafts catalyst, 41, 1 Amidation, of aniline with maleic anhydride, 41, 93... 

Catalysts like hydrogen fluoride or aluminum chloride catalyze not only the alkylation but the side reactions such as polymerization, isomerization, and disproportionation of tetrapropylene. All three side reactions are observed. In... 

The alkylation of halogen-substituted benzenes such as fluorobenzene and dichlorobenzenes with other (dichloroalkyl)silanes in the presence of aluminum chloride catalyst afforded isomeric mixtures of the corresponding (dihalogen-substituted phenyl)alkylsilanes in moderate yields (Eq. (13)). These results are summarized in Table Xll. 

Trialkylsilanes are generally more effective than dialkyl- or monoalkylsilanes in minimizing isomerizations. The reduction of 2-bromododecane to dodecane proceeds under aluminum chloride catalysis in 82% yield using n-butylsilane and in 87% yield with tri-n-butylsilane.186 However, similar treatment of bromo-cycloheptane with triethylsilane yields a mixture of 39% cycloheptane and 26% methylcyclohexane. The same substrate yields 65% methylcyclohexane and less than 1% cycloheptane when n -butylsilane is the reducing agent.186... 

The isomerization is usually complete in 5 hours and can easily be followed by vapor-phase chromatography. Heating periods up to 20 hours are not detrimental. The only failure among numerous preparations occurred when tetramethyl-1,3-cyclobutanedione contaminated with 4% of isobutyric acid was used. In case of partial conversion after 5 hours, additional increments (0.5 g.) of aluminum chloride should be added to complete the reaction. 

Allylchlorosilanes also react with naphthalene to give isomeric mixtures of poly-alkylated products. However, it is difficult to isolate and purify the products for characterization because the products possess similar boiling points. The alkylation of anthracene with allylchlorosilanes or vinylchlorosilanes is not possible because of the deactivation of aluminum chloride catalyst by complex formation with anthracene. 

Aluminum chloride has extensive commercial applications. It is used primarily in the electrolytic production of aluminum. Another major use involves its catalytic applications in many organic reactions, including Friedel-Crafts alkylation, polymerization, isomerization, hydrocracking, oxidation, decarboxylation, and dehydrogenation. It is also used in the production of rare earth chlorides, electroplating of aluminum and in many metal finishing and metallurgical operations. 

The mechanism of formation of two isomeric thienothiophenes by cyclization of 2-acetonylthio-thiophenes in the presence of aluminum chloride may be as shown in Scheme 1. 

Isomerization does not occur when the acetonylthio group is in the thiophene /J-position. Thus, 3-acetonylthio-thiophene with aluminum chloride in benzene results only in alkyl-substituted thieno[3,2-h]-thiophene (2) as shown by UV spectroscopy and the identity of acetyl derivatives of the cyclization products with those of well established alkyl-substituted thienothiophene 2 [Eq. (15)]. 

The process involves first separating mixed butane compounds by distillation to isobutane and n-butane. The n-butane is then mixed with hydrogen, heated and passed through a reactor containing a platinum catalyst or an HC1 activated aluminum chloride catalyst. The n-butane is isomerized to isobutane and separated. 

Isomerization A refinery process used to produce branched compounds from straight-chain molecules. Butane, pentane, and hexane are isomerized to branched, higher-octane compounds through isomerization. Isomerization reactions are catalyzed through the use of aluminum chloride and other metal catalysts. 

Frjedel-Crafts Reaction. Any organic reaction brought about by the catalytic action of anhydrous aluminum chloride or related, so-called Lewis acid type catalysts. Discovered in 1877 by C. Friedel and J.M. Crafts, who later uncovered most of the types of reaction such as substitution, isomerization, elimination, cracking, olefin polymerization, addition, etc. Commonly used to displace an aromatic hydrogen atom with an alkyl, aryl or acyl chain... 

Dyong and Bendlin52 pointed out the possibility of functionalization of sorbic acid at C-3, -4, and -5 in the desired way. Introduction of two hydroxyl groups, at CA and C-5, may be accomplished stereospecifi-cally by means of cis-hvdroxylation, or by intermediation of an epoxide. Michael-type addition of a nucleophile to C-3 of the conjugated double-bond provides the possibility of obtaining all four diastereo-isomeric products. In this way, N-acetyl-DL-acosamine (137, 3-acet-amido-2,3,6-trideoxy-DL-arabmo-hexopyranose) was synthesized from 133 (obtained from the epoxide 129 in an aluminum chloride-catalyzed reaction with acetone). The amide 134 wasN-acetylated and... 

Catalyst. In all of the commercial isomerization processes applied to paraffins and naphthenes, the catalyst is aluminum chloride plus hydrogen chloride. In the pure state, these two ingredients do not associate chemically (1), but they become associated in the presence of certain hydrocarbons normally occurring in petroleum stocks. 

The other vapor-phase butane isomerization process, developed cooperatively by the Anglo-Iranian Oil Co. and the Standard Oil Development Co., is somewhat similar to the Isocel process. In the AIOC-Jersey process (18), the reactor is initially filled with bauxite, and aluminum chloride is sublimed into the vaporized feed as necessary to maintain the desired catalyst activity. Upflow of vapor through the reactor is the customary arrangement. Since carry-over of aluminum chloride is not excessive at the usual rates of catalyst addition, about half of the commercial plants employing this process were not equipped with guard chambers. 

The butane isomerization process developed by the Universal Oil Products Co. is shown in Figure 4. In this process (3), the feed is maintained essentially in the liquid phase under pressure. Part of the feed is by-passed through a saturator, where it dissolves aluminum chloride. The feed later picks up hydrogen chloride and passes through the reactor, which is packed with quartz chips. Some insoluble liquid complex is formed, and this adheres to the quartz chips. The aluminum chloride in the feed is preferentially taken up by the complex, which thus maintains an active catalyst bed. The complex slowly drains through the reactor, losing activity en route. It arrives at the bottom in essentially spent condition and is discarded. Aluminum chloride carried overhead in the reactor products is returned to the reactor from the bottom of the recovery tower. The rest of the process is the same as in the vapor-phase processes. 

The other commercialized pentane isomerization process is that of the Standard Oil Co. (Indiana) (20). This process differs from the Indiana-Texas butane process in that the aluminum chloride is introduced as a slurry directly to the reactor and that about 0.5% by volume of benzene is added continuously in the feed to suppress side reactions. Temperature, catalyst composition, space velocity, and hydrogen chloride concentration are generally similar to those in the corresponding butane process, but the reactor pressure is about 100 pounds lower. The Pan American Refining Co. operated the Indiana pentane isomerization process commercially during the last nine months of the war and produced about 400 barrels of isopentane per calendar day. 

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