Phase alkylation

The in situ process is simpler because it requires less material handling (35) however, this process has been used only for resole resins. When phenol is used, the reaction system is initially one-phase alkylated phenols and bisphenol A present special problems. As the reaction with formaldehyde progresses at 80—100°C, the resin becomes water-insoluble and phase separation takes place. Catalysts such as hexa produce an early phase separation, whereas NaOH-based resins retain water solubiUty to a higher molecular weight. If the reaction medium contains a protective coUoid at phase separation, a resin-in-water dispersion forms. Alternatively, the protective coUoid can be added later in the reaction sequence, in which case the reaction mass may temporarily be a water-in-resin dispersion. The protective coUoid serves to assist particle formation and stabUizes the final particles against coalescence. Some examples of protective coUoids are poly(vinyl alcohol), gum arabic, and hydroxyethjlceUulose. 

Vapor-Phase Processes. Although vapor-phase alkylation has been practiced since the early 1940s, it could not compete with Hquid-phase processes until the 1970s when the Mobil—Badger vapor-phase ethylbenzene process was introduced (Eig. 4). The process is based on Mobil s ZSM-5 zeohte catalyst (38,52,53). The nonpoUuting and noncorrosive nature of the process is one of its major advantages over the AlCl hquid-phase system. 

Methylphenol. This phenol, commonly known as o-cresol, is produced synthetically by the gas phase alkylation of phenol with methanol using modified alumina catalysis or it may be recovered from naturally occurring petroleum streams and coal tars. Most is produced synthetically. Reaction of phenol with methanol using modified zeoHte catalysts is a concerted dehydration of the methanol and alkylation of the aromatic ring. 2-Methylphenol [95-48-7] is available in 55-gal dmms (208-L) and in bulk quantities in tank wagons and railcars. 

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. 

Alkylation. Ethylbenzene [100-41 -4] the precursor of styrene, is produced from benzene and ethylene. The ethylation of benzene is conducted either ia the Hquid phase ia the preseace of a Eriedel-Crafts catalyst (AlCl, BE, EeCl ) or ia the vapor phase with a suitable catalyst. The Moasanto/Lummus process uses an aluminum chloride catalyst that yields more than 99% ethylbenzene (13). More recently, Lummus and Union Oil commercialized a zeoHte catalyst process for Hquid-phase alkylation (14). Badger and Mobil also have a vapor-phase alkylation process usiag zeoHte catalysts (15). Almost all ethylbenzene produced is used for the manufacture of styrene [100-42-5] which is obtained by dehydrogenation ia the preseace of a suitable catalyst at 550—640°C and relatively low pressure, <0.1 MPa (<1 atm). 

Sulphoxides can be used as phase transfer catalysts, for example, a-phosphoryl sulphoxides (Scheme 24) have been used as phase transfer catalysts in the two-phase alkylation of phenylacetonitrile or phenylacetone with alkyl halides and aqueous sodium hydroxide. However, they are considered to be inefficient catalysts for simple displacement reactions226. 

TABLE 21. Liquid-liquid two-phase alkylation catalyzed by various sulphoxides... 

The aim of the present work was the investigation of the catalytic reactivity of different salts (K, NH4, Cs ) of H3PW12O40 and H4SiWi2O40 with various compositions in continuous liquid phase alkylation and its comparison with n-butane isomerisation reaction in gas phase. 

Liquid-phase alkylation of phenol with t-Butanol over H-MCM-22, H-ITQ-2 and H-MCM-36 catalysts... 

In terms of economical synthetic approaches to indoles, the synthesis of this heterocycle from anilines and trialkylammonium chlorides was effected in an aqueous medium (H20-dioxane) at 180°C in the presence of a catalytic amount of ruthenium(III) chloride hydrate and triphenylphosphine together with tin(II)chloride <00TL1811>. Muchowski devised a novel synthetic route to indole-4-carboxaldehydes and 4-acetylindoles 86 via hydrolytic cleavage of W-alkyl-5-aminoisoquinolinium salts 85 to homophthaldehyde derivatives upon heating in a two phase alkyl acetate-water system containing an excess of a 2 1 sodium bisulfite-sodium sulfite mixture <00JHC1293>. 

In contrast with standard liquiddiquid two-phase alkylation reactions, it is possible to use iodoalkanes with only catalytic amounts of the ammonium salts in the absence of an added solvent under soliddiquid conditions [e.g. 80]. 

The catalytic effect of quaternary ammonium salts in the basic liquid liquid two-phase alkylation of amines [1-3] is somewhat unexpected in view of the low acidity of most amines (pKfl>30). Aqueous sodium hydroxide is not a sufficiently strong base to deprotonate non-activated amines in aqueous solution and the hydroxide ion is not readily transferred into the organic phase to facilitate the homogeneous alkylation (see Chapter 1). Additionally, it is known that ion-pairs of quaternary ammonium cations with deprotonated amines are decomposed extremely rapidly by traces of water [4]. However, under solidrliquid two-phase conditions, the addition of a quaternary ammonium salt has been found to increase the rate of alkylation of non-activated amines by a factor of ca. 3-4 [5]. Similarly, the alkylation of aromatic amines is accelerated by the addition of the quaternary ammonium salt the reaction is accelerated even in the absence of an inorganic base, although under such conditions the amine is deactivated by the formation of the hydrohalide salt, and the rate of the reaction gradually decreases. Hence, the addition of even a weak base, such as... 

The catalysed two-phase alkylation of carboxamides has the advantages of speed and simplicity over the traditional procedures and provides a valuable route to secondary and tertiary amines by hydrolysis or reduction of the amides, respectively. The procedure appears to be limited, however, to reactions with primary haloalkanes and dialkyl sulphates, as secondary haloalkanes are totally unreactive [6, 7]. The use of iodoalkanes should be avoided, on account of the inhibiting effect of the released iodide ion on the catalyst. Also, the A-alkylation reaction is generally susceptible to steric effects, as seen by the low yields in the A -cthylation of (V-/-butylacetamide and of A-ethylpivalamide [6]. However, the low steric demand of the formyl group permits A,A-dialkylation and it is possible to obtain, after hydrolysis in 60% ethanolic sulphuric acid, the secondary amines having one (or, in some cases, two) bulky substituent(s) [7]. 

The analogous solidtliquid two-phase alkylation at the more acidic NH position of the diphenylphosphinic hydrazides (Table 5.27) proceeds smoothly in the presence of tetra-rt-butylammonium hydrogen sulphate [54], No reaction occurs under the standard liquiddiquid conditions. Hydrolysis of the A-alkylated phosphinic hydrazides in refluxing dilute hydrochloric acid provides a convenient and efficient route to A-alkylhydrazines [54], The reaction has been extended to the preparation of A. A -dialkylhydrazines from diphenylphosphinic hydrazide by acylation of the... 

The two-phase alkylation reactions have been extended to the acylation of simple heteroaromatic systems. Generally, the required conditions are milder than those employed for the alkylation reactions, but an excess of the acylating agent is usually required, owing to its facile hydrolysis in the basic media. Thus, benzimidazole and its 2-alkyl and 2-aryl derivatives have been benzoylated [46], and pyrrole and indole have been converted into a range of A-acyl [47, 48] and A-sulphonyl derivatives [48-53] (Table 5.35 and Table 5.36). 

Liquid liquid two-phase alkylation of pyridones and related systems... 

Alkylation of the 2-(l,2-dihydropyrid-2-yl)indane-l,3-diones (3) (Scheme 5.18) by traditional methods, using sodium hydride in apolar or dipolar solvents, leads to a mixture of the C2- and A-alkylated derivatives in moderate to low yield (Scheme 5.18). In contrast, two-phase alkylation results in almost complete regioselective N-alkylation in high yield [64],... 

The reachon of benzene with ethylene or propylene to form ethylbenzene or isopropylbenzene (cumene) is an industrially important transformahon, with ethylbenzene as the key building block for polystyrene and cumene as the feedstock for phenol produchon [55]. Fthylbenzene was originally produced with a Lewis acid catalyst consishng of AlCfi or a Bronsted acidic solid phosphoric acid (SPA) catalyst [56]. Both catalyst systems suffered from equipment corrosion so, in the 1980s the Mobil-Badger vapor phase alkylation process was introduced, which... 

Liquid phase alkylation of benzene with propylene to make cumene can be used to illustrate the general reaction mechanism for the alkylation of aromatics with... 

Cradun, 1., Reyniers, M.-F., and Marin, G.B. (2007) Effects of add properties of Y zeolites on the liquid phase alkylation of benzene with 1-octene a reaction analysis. /. Mol. Sci. A Chem., 277,... 

Erecan, C., Dautzenberg, F., Yeh, C.Y., and Bamer, H.E. (1998) Mass transfer effects in liquid phase alkylation of benzene with zeolite catalysts. Ind. 

Magnoux, Z.D. and Guisnet, M. (1999) Liquid phase alkylation of toluene with 1-heptene over a HFAU zeolite evidence for transalkylation between toluene and non-desorbed products. Appl Catal A, 182, 407-411. 

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