Reaction with alkylbenzenes

Follow the step by step operating procedures. Then, once the required preheating temperatures are reached (normally witiiin two hours), the plant will be ready for sulphur ignition sulphur dosing and sulphur igniter will be started, the conversion of SO2 SO3 will proceed from an initial 50% value to 98% and the sulphonation reaction with alkylbenzene will result in a partially-converted alkylbenzene sulphonic acid, to be returned to the off-spec circulation tank. 

The benzylic position of an alkylbcnzene can be brominated by reaction with jV-bromosuccinimide, and the entire side chain can be degraded to a carboxyl group by oxidation with aqueous KMnCfy Although aromatic rings are less reactive than isolated alkene double bonds, they can be reduced to cyclohexanes by hydrogenation over a platinum or rhodium catalyst. In addition, aryl alkyl ketones are reduced to alkylbenzenes by hydrogenation over a platinum catalyst. 

Further evidence against the formation of a free carbonium ion in the alkylation reaction is obtained from the fact that in the presence of boron trifluoride-phosphoric acid catalyst, but-l-ene, but-2-ene, and i-butene react at different rates with alkylbenzenes, yet they would each give the same carbonium ion. In addition, only the latter alkene gave the usual activation order (in this case the hyper-... 

The reaction of alkylbenzenes with copper(II) bromide is critically influenced by the presence of water in small quantities (ref. 10). With toluene, nuclear bromination predominates in a rigorously anhydrous system. When small amounts... 

As an alternative to radical chlorination, use has been made of carbon tetrachloride and hexachloroethane in the presence of a quaternary ammonium salt, as source of the chloronium ion for reaction with activated alkylbenzenes [38], Benzyl chlorides need the additional activation of a nitro group for their conversion into the corresponding nitrobenzotrichlorides, whereas benzal chlorides do not need the extra activation for a similar conversion. The same synthetic protocol, using hexachloroethane, has been used for the conversion of allylic sulphones into the 1,1-dichloro derivatives [39],... 

Electron-transfer reactions are normally performed in polar solvents such as acetonitrile (MeCN), in which the product ions of the electron transfer are stabilized by the strong solvation [6,7]. When a cationic electron acceptor (A ) is employed in electron-transfer reactions with a neutral electron donor (D), the electron transfer from D to A+ produces a radical cation (D +) and a neutral radical (A ). In such a case, the solvation before and after the electron transfer may be largely canceled out when the free-energy change of electron transfer is expected to be rather independent of the solvent polarity. The solvent independent value is confirmed by determination of the Eqx values of alkylbenzene derivatives (electron donors) and Ered values of acridinium cations (electron acceptors) in solvents with different polarities [79]. The E°ox values of alkylbenzene derivatives in a less polar solvent (CH2CI2) are shifted to the positive direction by about 0.1 V... 

Linear alkylbenzenes are made from -paraffms (Cio-Cu) by either partial dehydrogenation to olefins and addition to benzene with HF as catalyst (60%) or chlorination of the paraffins and Friedel-Crafts reaction with benzene and an aluminum chloride catalyst (40%). See Chapter 24 for more information. 

The reaction works with alkylbenzenes, phenols, their ethers, and many heterocycles, it doesn t work with aromatic amines. 

The reaction of alkylbenzenes with ethylene in the presence of sodium occurs with successive replacement of one or two benzylic hydrogens to produce mono-and diethylated compounds.235 Propylene reacts to form isomeric products with the preponderance of the branched isomer236 [Eq. (5.61)]. When potassium is used as catalyst, indan derivatives can also be formed237 [Eq. (5.62)] ... 

Dienes react quite readily with alkylbenzenes to form monoalkenylbenzenes under controlled experimental conditions. Sodium and potassium deposited on calcium oxide were found to be very suitable catalysts for these alkenylation reactions.240 Naphthalene-sodium in tetrahydrofuran is a very effective catalyst... 

The initial hydroxylation of benzene, toluene, and other alkylbenzenes is accomplished by multicomponent aromatic ring dioxygenases that introduce two oxygen atoms to form diols.158 Dioxygenation of benzoate yields a diol that can be oxidatively decar-boxylated by reaction with NAD+ (Eq. 25-7) to form catechol.157,162 Toluene gives 3-methylcatechol... 

Two of the reactions that are used in the industrial preparation of detergents are electrophilic aromatic substitution reactions. First, a large hydrocarbon group is attached to a benzene ring by a Friedel-Crafts alkylation reaction employing tetrapropene as the source of the carbocation electrophile. The resulting alkylbenzene is then sulfonated by reaction with sulfuric acid. Deprotonation of the sulfonic acid with sodium hydroxide produces the detergent. 

Ring expansion of aromatic compounds by carbene, carbethoxycarbene, chlorocarbene, and carbenoid is well known 256, 336, 351-356). Muller and co-workers reported the reaction of aromatic compounds with carbene generated from a catalytic decomposition of diazomethane with copper salts, and proposed a bimolecular two-step mechanism involving an inverse ylid for the reaction. Miller (336) proposed another bimolecular two-step mechanism for the reaction of benzene with alkylcarbenoids of aluminum. Baldwin and Smith (25) proposed a concerted mechanism for the reaction of aromatic compounds with carbethoxycarbene. Reaction of alkylbenzene with diethylzinc and ethylidene iodide gives 7-methylcyclohepta-l,3,5-triene derivatives in yield 369). The... 

And 2-Alkylpyridine with Diolefins, Styrenes, and Vinylpyridines. The reaction of alkylpyridines with isoprene, styrenes, and vinylpyridines occurs at 0-25°. The yields of adducts are high, and the compounds formed are those predicted from similar reactions made with alkylbenzenes (30). 

Carbonium ions can be generated at a variety of oxidation levels. The alkyl carbocation can be generated from alkyl halides by reaction with a Lewis acid (RCl + AICI3) or by protonation of alcohols or alkenes. The reaction of an alkyl halide and aluminium trichloride with an aromatic ring is known as the Friedel-Crafts alkylation. The order of stability of a carbocation is tertiary > secondary > primary. Since many alkylation processes are slower than rearrangements, a secondary or tertiary carbocation may be formed before aromatic substitution occurs. Alkylation of benzene with 1-chloropropane in the presence of aluminium trichloride at 35 °C for 5 hours gave a 2 3 mixture of n- and isopropylbenzene (Scheme 4.5). Since the alkylbenzenes such as toluene and the xylenes (dimethylbenzenes) are more electron rich than benzene itself, it is difficult to prevent polysubsiitution and consequently mixtures of polyalkylated benzenes may be obtained. On the other hand, nitro compounds are sufficiently deactivated for the reaction to be unsuccessful. 

In another study, tertiary secondary primary relative reactivity data (TSP selectivity) for the deprotonation reactions of alkylbenzene radical cations [ 153] showed that with both intra- and intermolecular TSP selectivity the order S > T > P is usually observed, suggesting that the combination of steric and stereoelectronic effects makes an /Pr group less reactive than Et, but still more reactive than Me. 

Most aromatic compounds, whether of high or low reactivity, can be nitrated, because a wide variety of nitrating agents is available. For benzene, the simple alkylbenzenes, and less reactive compounds, the most common reagent is a mixture of concentrated nitric and sulfuric acids,but for active substrates, the reaction can be carried out with nitric acid alone, or in water, acetic acid, acetic anhydride, or chloroform.Nitric acid in acetic anhydride/trifluoroacetic anhydride on zeolite H-(3 was used to convert toluene to 2,4-dinitrotoluene, and AcONOi on clay converted ethylbenzene to ortho-para nitro ethylbenzene. " In fact, these milder conditions are necessary for active compounds, such as amines, phenols, and pyrroles, since reaction with mixed nitric and sulfuric acids would oxidize these substrates. With active substrates, such as amines and phenols, nitration can be accomplished by nitrosation under oxidizing conditions with a mixture of dilute nitrous and nitric acids.A mixture of N02/02/Fe(acac)3 can be used for active compounds, as can NaN02 with trichloroisocyanuric acid on wet silica gel, or N2O4 and silica acetate. Trimethoxybenzenes were nitrated easily with ceric ammonium nitrate on silica gel, and mesitylene was nitrated in an... 

On the other hand, thiocarbamoyl chlorides (15) may be used in thioamide synthesis, though via carbon-carbon bond formation in Friedel-Crafts-type reactions (c/. Volume 2, Chapter 3.1). The approach is limited to fairly electron-rich aromatics such as alkylbenzenes, anisole, and furan, but fails for benzene equation (7) gives some details. - Phenol does not require a Lewis acid catalyst in the reaction with H CSCl, but gives a mixture of 2-/4-hydroxythiobenzamides along with O-phenyl thiocarba-mate. ... 

The results of numerous kinetic studies on the reaction of cobalt(III), mangane-se(III) and various other metal acetates in acetic acid with alkylbenzenes under anaerobic conditions [13, 14], but especially of course in the presence of dioxygen, are compatible with a generally accepted mechanism [12, 14, 15]. 

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