Coupling butyl 3- acrylate

The oxidative Heck-Mizoroki reaction has also been adapted to flow-chemistry systems. Lahred and coworkers have used this procedure to couple -butyl acrylate and -butyl vinyl ether with arylboronic acids using Pd(OAc)2 with />-benzoquinone as the oxidant [88]. The yields were generally good (56-85%). 

General procedure for Heck coupling. A mixture of POPd (16.0 mg, 6 mol%), quinoline derivative (0.56 mmol), tert-butyl acrylate (356 mg, 2.8 mmol), and base (0.61 mmol) was stirred in 5 mL of anhydrous DMF at 135 °C for 24 h. The reaction mixture was allowed to cool to room temperature, quenched with water, and extracted with Et20. The combined organic layers were washed with water, dried over MgS04, and the solvents were removed under vacuum. The crude products were purified by flash chromatography on silica gel. 

Bauer et al. describe the use of a noncontact probe coupled by fiber optics to an FT-Raman system to measure the percentage of dry extractibles and styrene monomer in a styrene/butadiene latex emulsion polymerization reaction using PLS models [201]. Elizalde et al. have examined the use of Raman spectroscopy to monitor the emulsion polymerization of n-butyl acrylate with methyl methacrylate under starved, or low monomer [202], and with high soUds-content [203] conditions. In both cases, models could be built to predict multiple properties, including solids content, residual monomer, and cumulative copolymer composition. Another study compared reaction calorimetry and Raman spectroscopy for monitoring n-butyl acrylate/methyl methacrylate and for vinyl acetate/butyl acrylate, under conditions of normal and instantaneous conversion [204], Both techniques performed well for normal conversion conditions and for overall conversion estimate, but Raman spectroscopy was better at estimating free monomer concentration and instantaneous conversion rate. However, the authors also point out that in certain situations, alternative techniques such as calorimetry can be cheaper, faster, and often easier to maintain accurate models for than Raman spectroscopy, hi a subsequent article, Elizalde et al. found that updating calibration models after... 

Other Pd(II) complexes with imidazole-like ligands were also specifically synthesized for improved solubility in ionic liquids (258). The catalysts were applied for the Heck Coupling of iodobenzene with -butyl acrylate in [BMIM]PF6 in the presence of Et N at 120°C. One catalyst (Scheme 27) was especially well retained without any loss of activity even at fairly low catalyst loading (0.2mol%) for more than five repeated uses. In all cases, > 99% yield was achieved within 1 h. 

The Heck reaction is a C-C coupling reaction where an unsaturated hydrocarbon or arene halide/triflate/sulfonate reacts with an alkene in presence of a base and Pd(0) catalyst so as to form a substituted alkene. Kaufmann et al. showed that the Heck reaction carried out in presence of ILs such as tetra-alkyl ammonium and phosphonium salts without the phosphine ligands, resulted in high yields of product. They attributed the activity to the stabilizing effect of ammonium and phosphonium salts on Pd(0) species. Carmichael et al. used ionic liquids containing either A,A -dialkylimidazolium and A-alkylpyridinium cations with anions such as halide, hexafluorophosphate or tetrafiuoroborate to carry out reactions of aryl halide and benzoic anhydride with ethyl and butyl acrylates in presence of Pd catalyst. An example of iodobenzene reacting with ethyl acrylate to give trans-et vy cinnamate is shown in Scheme 14. 

Palladium(II) effects orthometalation of acetanilides to form the corresponding palladacycles [185]. De Vries, van Leeuwen, and coworkers exploited this reactivity to achieve regioselective oxidative coupling of acetaniUdes and n-butyl acrylate that proceeds efficiently with BQ as the stoichiometric oxidant (Eq. 46) [ 186], The use of TsOH as an additive and acetic acid as a cosolvent significantly improves the results. Inferior results are observed with hydrogen peroxide or copper(II) acetate as the stoichiometric oxidant, but efforts to use molecular oxygen were not described. 

Most recently, the test has been applied to examination of the mechanism of a heterogeneous Heck reaction, promoted by Pd on alumina [25]. In the presence of the solid catalyst, 4-iodobenzamide coupled efficiently with butyl acrylate yielding the cinnamate, and it was suspected that the catalytic agent was a soluble form of palladium released from and then recaptured by the alumina support. To test this, the amide was attached to a commercially available resin with suitable functionality, and the supported amide (15 in Scheme 9.10) was allowed to react with the acrylate and Pd on alumina. The same product, identified after release from the polymer by TFA treatment, was formed, and further experiments were able to narrow down the form of the soluble catalysing palladium species. 

Figure 7.1.9 Contour plot obtained for a typical GPC-NMR on-line coupling analysis of a styrene-butyl acrylate copolymer...

Figure 7.1.11 Study of the copolymerization course of the butyl acrylate-styrene system, using GPC-NMR coupling, in the first two time-intervals (- -) 15 min (- -) 30 min...

Figure 2.12 Dimer-monomer pre-equilibrium and catalytic cycle for the Heck coupling of p-bromocyanobenzene and n-butyl acrylate.

Table 1. Coupling of aniline derivatives with n-butyl acrylate using Pd(OAc)2a.

General Procedure for Coupling Acetanilide Derivatives to n-Butyl Acrylate... 

Homopolymer PS and block copolymer poly(tert-butyl acrylate)-b-styrene, prepared by nitroxide-mediated living free-radical polymerization, were utilized for the functionalization of shortened SWCNTs through a radical coupling reaction (Scheme 1.33) [194]. 

The first palladium catalyzed reaction reported in an ionic liquid, by Kaufmann in 1996, was a Heck reaction.15 A series of aryl bromides were efficiently coupled with n-butyl acrylate in tributylhexadecylphosphonium bromide ([Ci6PBu3]Br) and tetrabutylammonium bromide ([NBu4]Br) to afford the trans-cinnamates in yields of over 90% in some cases (Scheme 1). Product isolation was achieved by distillation from the ionic liquid or by solvent extraction. 

The first example of a Heck reaction in a molten salt stems from as early as 1996 when tetraalkylammonium and phosphonium halides were used as reaction media for the coupling between arylhalides and n-butyl acrylate. Particularly good results were achieved in trihexyl(tetradecyl)phosphonium chloride, both in terms of reactivity and ease of product isolation. 

To begin with, the reactivity of 9.92 was compared to a typical substrate, butyl acrylate, in solution. Reaction with a common aryl halide produced similar reaction yields of 9.94 and 9.95, respectively (Fig. 9.37, top). The reactivity of 9.92 and butyl acrylate were then compared on solid phase, using 9.93, standard coupling conditions, and various reaction times (Fig. 9.37, bottom). The coupling to give 9.96 was complete after 4 h, with the fluorescence of the beads treated with 9.92 being either weak (55% conversion by fluorescence measurement, 2 h) or strong (quantitative conversion, 4 h). 

These palladium and platinum (completely analogous to palladium) complexes were used in the C-C coupling reaction of aryl bromides carrying functional groups in the para position with styrene or n-butyl acrylate at elevated temperatures. 

The same nickel catalyst was also used for the Heck reaction between 4-bromobenzoni-trile and butyl acrylate [453] as well as Suzuki coupling between substituted aryl halides (Cl, Br) and phenylboronic acid (see Figure 3.151). 

A phosphine-based nickel(II) bromide complex (Ni-2) also induces living radical polymerization of MMA specifically when coupled with a bromide initiator in the presence of Al(0-i-Pr)3 as an additive in toluene at 60 and 80 °C.133 The reaction rates and the effects of radical inhibitors are similar to those with Ni-1, whereas chloride initiators are not effective in reaction control. Additives are not necessary when the polymerization is carried out in the bulk or at high concentrations of monomer, either methacrylate or /v-butyl acrylate (nBA).134 An alkylphosphine complex (Ni-3) is thermally more stable and can be employed for MMA, MA, and nBA in a wide range of temperatures (60—120 °C) without additives.135 A fast polymerization proceeds at 120 °C to reach 90% conversion in 2.5 h. A zerovalent nickel complex (Ni-4) is another class of catalyst for living radical polymerization of MMA in conjunction with a bromide initiator and Al(0-i-Pr)3 to afford polymers with narrow MWDs MJMn = 1.2—1.4) and controlled molecular weights.136 The Ni(0) activity is similar to that of Ni(II) complexes whereas the controllability... 

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