Dodecene, alkylation

Figure 10. Activity of clay catalysts for 1-dodecene alkylation of benzene at 473 K (reaction time = 3 h 1 = starting montmorillonite 2 = acid treated montmorillonite 3 = acid treated montmorillonite calcined at 773 K per 4 h 4 = pillared montmorillonite calcined at 773 K for 4 h 5 = acid treated pillared montmorillonite calcined at 773K for 4 h 6 = KIO) [83].

Scheme 5.1-56 The alkylation of benzene with dodecene with an ionic liquid on a solid support.

Sulphated zirconia catalysts can be acidic or superacidic depending on the method of treatment. A variety of acid-catalysed reactions, referred to earlier in this section, can be carried out with sulphated zirconia. Yadav and Nair (1999) have given a state-of-the art review on this subject. Examples of benzylation of benzene with benzyl chloride / benzyl alcohol, alkylation of o-xylene with. styrene, alkylation of diphenyl oxide with 1-dodecene, isomerization of epoxides to aldehydes, acylation of benzene / chlorobenzene with p-chloro benzoylchloride, etc. are covered in the review. 

Aromatic alkylation is illustrated in this paper for both individual a-olefin cuts (e.g. 1-decene and 1-dodecene) as well as typical samples of Ci0-Ci4 paraffin dehydrogenate that contain ca. 8.5% Go-Cm olefins, primarily internal olefins. Syntheses have, for the most part, been conducted in a continuous reactive distillation unit of the type illustrated in Figure 1, operated slightly above atmospheric pressure. Operational details for this unit may be found in the previous section. 

Table 1 Benzene alkylation with 1-dodecene and 1-decene, using fluorided-moidenite catalyst.

Performances of these acidic mordenite zeolites have been examined as a function of the level of fluoride treatment. For mordenites treated with HF to fluoride levels of 0.25, 0.5, and 1.0%, batch alkylation at ca. 80 °C of typical benzene/l-dodecene mixtures show (after 1 hr) very similar levels of activity and 2-... 

Cao, Y., Kessas, R., Naccache, C., and Taarit, Y.B. (1999) Alkylation of benzene with dodecene. The activity and selectivity of zeolite type catalysts as a function of the porous structure. Appl. Catal, 184, 231-238. 

Olefins by reaction of alkyl phenyl tellurides with chloramine-T (typical procedure). A solution of 1-dodecyl phenyl telluride (0.198 g, 0.52 mmol) and commercial chloramine-T trihydrate (0.300 g, 1.0 mmol) in THF (5 mL) is refluxed for 40 min under Nj. After evaporation of the solvent, the residue is treated with hexane (20 mL), and then fdtered. The filtrate is passed through a short Si02 column with hexane, giving, after evaporation, 1-dodecene as a colourless oil (0.068 g (78%)). 

The nonlinear dodecene was then used to alkylate benzene by the Friedel-Crafts procedure. Sulfonation and treatment with caustic completed the process. 

The alkylation of a number of aromatic compounds through the use of a chloroa-luminate(III) ionic liquid on a solid support has been investigated by Holderich and co-workers [87, 88]. Here the alkylation of aromatic compounds such as benzene, toluene, naphthalene, and phenol with dodecene was performed using the ionic liquid [BMlM]Cl/AlCl3 supported on siHca, alumina, and zirconia. With benzene, monoalkylated dodecylbenzenes were obtained (Scheme 5.1-56). 

Silica-alumina particles coated with a permselective silicalite membrane is almost completely selective in the formation of p-xylene in the disproportionation of toluene.402 Friedel-Crafts alkylations were performed in ionic liquids. The strong polarity and high electrostatic fields of these materials usually bring about enhanced activity.403 404 Easy recycling is an additional benefit. Good characteristics in the alkylation of benzene with dodecene were reported for catalysts immobilized on silica or MCM-41 405... 

Not only benzene and its alkyl derivatives can be used as the aromatic component but also naphthalene [341], phenol [340,341] and thiophene [341,342]. Low-molecular weight alkenes, Cj to C5, cyclohexene and dodecene have served as alkylating agents. 

Fig. 45. Catalytic activities of solid acids for reaction of liquids Alkylation of 1,3,5-tri-methylbenzene with cyclohexene (373 K) alkylation of phenol with 1-dodecene rearrangement of benzopinacol. (From Ref. 249.)...

Harmer et al.196 used 1,1,2,2-tetrafluoroethanesulfonic acid in the alkylation of para-xylene with 1-dodecene. The silica-embedded catalyst prepared by the sol-gel method showed much higher activity than the neat acid (almost complete conversion in 15 min at 100°C over the sol-gel-derived material versus 10% conversion, using the same molar amounts of acid). Practically no leaching was detected and the catalyst could be recycled with a slight decrease in conversion. It is in sharp contrast with silica-supported triflic acid, which showed much lower activity due to the loss of volatile triflic acid. 

Dimethylcarbene The usual methods for generation of carbenoids lead to poor results in the case of dimethylcarbene. The most satisfactory method involves generation in the presence of an alkene by a-elimination with n-butyllithium from 2,2-dibromopropane (which must be completely free from acetone or 2-bromoacetone), used after a detailed study of cyclopropanation of tetramethylethylene (equation I). n-Butyllithium is superior to methyl- or isopropyllithium. Addition of TMEDA or KOC(CH3)3 completely supresses cyclopropanation. Yields are improved by a lower reaction temperature. In all experiments, 35-45% of the alkene is recovered. Yields decrease with a decrease of alkyl substituents on the double bond thus the yield is only 9% in the case of l-dodecene. No cyclopropane was obtained from 2-norbomene. 

The alkylation reactions of toluene and benzene with dodecene were used as test reactions in order to evaluate the catalyst activity. It could be observed that the IL is catalytically activity after being immobilised. Moreover, due to the better dispersion of the solid catalyst in the reaction media, even the conversions obtained for the supported IL were better than for the pure IL. In the alkylation of toluene conversions reached at standard conditions were twice as high for the immobilised ILs, for benzene the difference was even bigger. 

When alkylating benzene with dodecene, standard reaction conditions were a reaction temperature of 80°C and a catalyst ratio of 6 wt% catalyst over the total amount of reactants. Dodecene conversion reached 95 mol % with a selectivity of 98% towards monoalkylated products in the first 30 minutes of the reaction. In this case, benzene was used as solvent (molar ratio of benzene to dodecene = 10 1). 

T = 20°C, WHSV=7.8 h1, cat. T350/IL, R = 10 1 Figure 14 Alkylation of benzene with dodecene Continuous liquid phase... 

The third case shows the immobilisation of Lewis-acidic ionic liquids. The resulting catalysts, named Novel Lewis-Acidic Catalysts (NLACs), are highly active in the Friedel-Crafts alkylation of aromatic compounds with dodecene. Conversions and selectivities to the desired monoalkylated products were excellent. No leaching of the catalytically active component could be observed. The isomer distribution of the monoalkyated products is very similar to that obtained over pure aluminum(III)chloride. The main drawback of the NLACs is that thy are very sensitive towards water, which leads to irreversible deactivation. A second problem is the deactivation after long reaction times. The most likely cause is olefin oligomerisation. 

As a test reaction, the alkylation of benzene with dodecene was chosen. The batch reactor system consisted of a round-bottomed flask (slurry reactor) provided with a cooler, gas-inlet valve, and sampling exit. A magnetic stirrer equipped with a thermostat and a silicon oil bath were used to maintain the reaction temperature and ensure the homogeneity of reactants. The catalyst was weighed in the reactor and then benzene was added according to the proportion desired, followed by the addition of dodecene. 

Table 2 Results for the alkylation of benzene with dodecene, catalysed NLACs...

A survey of the literature reveals that the majority of the nonbiodegradable detergents are alkylbenzene sulfonates (ABS). Theoretically, there are over 80,000 isomeric alkylbenzenes in the range of C10 to C15 for the alkyl side chain. Costs, however, generally favor the use of dodecene (propylene tetramer) as the starting material for ABS. 

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