Acrylate telomerization

A simple template-free methyl acrylate telomerization was conducted using the cyclohexyl iodide/allyltributyltin system in order to identify retention times for the telomers 26 from the ACT reactions. Telomerization of methyl acrylate (900 mM) with 120 mM cyclohexyl iodide and 300 mM allyltributyltin gave 27% of the n=4 telomers. Scheme 8-10. Under the best GC conditions found, only four different n=4 telomers, out of a possible 16, were observed in this product mixture. This experiment gives a baseline value for telomer distribution obtained without the use of a template. It is clear that simple template-free telomerization is not useful for the preparation of an oligomer of a specific length. 

Scheme 8-10 Histogram for template-free methyl acrylate telomerization with 900 / 20 /300 ...

The feasibility and practicality of the ACT sequence in obtaining diastereomerically pure n=4 telomers were investigated using the optimum conditions determined for template 24. The possibility of isolation of the desired n=4 template from all of the other reaction products by the use of HPLC was explored. In a standard template-free stereorandom methyl acrylate telomerization, three peaks are observed for the = 3 telomers by normal-phase HPLC and three more broad peaks are separated for the =4 telomers. Each of these latter peaks represents a mixture of isomers as determined by GC analysis. 

Photolysis of this polymer gives radicals on which side chains can be formed, giving graft polymerization 122, 123, 153). Similarly the polymerization of styrene (152) or vinyl acetate (157) in the presence of bromotrichloromethane gives telomers carrying terminal bromine atoms and trichloromethyl groups. By ultraviolet irradiation (3500 A) in the presence of methyl methacrylate the carbon-bromine links are broken and block copolymers are formed. The telomerization of acrylonitrile and acrylic acid with bromoform is based on the same technique the end groups of both polyacrylonitrile and polyacrylic acid were photolyzed in the presence of acrylamide and afforded polyacrylamide blocks linked to polyacrylonitrile or polyacrylic acid blocks (164, 165). 

From a, bis(triehloromethyled) telogens, we carried out various telomerizations with methyl undeeylenate [59], ethylene [60], vinyl acetate [61] aUyl acetate [62-63], and with acrylates [61, 64]. We can notice that the aJlyl and acrylic derivatives lead to a mixture made of monoacetate and diadduct [63] ... 

Vinyl chloride can also be telomerized by free-radical initiation uo> in the presence of trichloroacetic acid or of the monoadduct of CC14 and acrylic (or methacrylic) acid (obtained with Cu+ +/CH3CN) ... 

A similar strategy was reported by Asahi Glass which prepared fluoroacrylic (FA) diblock copolymem used as surface active agents [117]. Acrylates containing perfluorinated groups were telomerized with mercapto acetic acid followed by the condensation of the telomer produced with polypropylene oxide (PPO) to yield PPO-t-PFA diblock copolymers. 

The telomerization process is certainly an appropriate technique for the synthesis of (meth)acrylic-type macromonomers, but also of (meth)acrylo-nitrile-derived macromonomers. This technique is open to almost all conventional monomers but is also devoted to original monomers such as NIPAM. We can note that macromonomers based on halogenated monomers were synthesized by telomerization, using redox catalysis. 

A series of telomerizations were performed in which the auxiliaries were varied in an attempt to determine which factors influence the penultimate effect. Bulky auxiliary groups analogous to those shown in Fig. 3 were used, and mixed auxiliary telomerizations were performed in which methyl acrylate was co-telomerized with the acrylimides. In cases where auxiliaries were sterically bulky and especially when... 

Palladium(I) intermediates have been proposed for the telomerization of butadiene with acetic acid yielding acetoxyoctadienes, and in a recent review the involvement of Pd(I) has been snggested for processes in which Pd(II) had been formerly suggested. These processes include alkene isomerization, methoxycarbonylation of alkynes to acrylic esters, and the aryloxycarbonylation of allyl alcohol. 

The first successful result was seen in the grafting of poly(octadecyl acrylate) onto silica and its application for separation of PAHs in a reversed phase mode. The polymer is obtained by telomerization of octadecyl acrylate, initiated with 3-mercaptopropyltrimethoxysilane (Fig. 1). The following immobilization is carried out by mixing with porous silica in a suitable solvent. The resultant polymer-grafted silica shows, not only extremely high separation of PAHs, but also specific temperature dependency on the selectivity, which is induced by an ordered-to-disordered transition of the grafted polymer. The detail is described later. 

It is difficult to control the stereoregularity of polymers in radical telomerization. However, the side chain ordering in the polymer can be realized if a long-chain alkyl compound is chosen as a vinyl monomer for telomerization. A preliminary example is reported with poly(octadecyl acrylate), ODA . The resultant polymer can be easily grafted onto porous silica through a terminal trimethoxy-silyl group. Toluene and tetrachloromethane are good solvents for this procedure. 

In this entry, several kinds of comb-shaped polymers with highly ordered side chains have been introduced as attractive organic phases for RP-HPLC. Poly(octadecyl acrylate), ODA , is one of the simplest comb-shaped polymers, and its grafting for introduction onto silica surface is done by a one-step telomerization with 3-mercaptopropyl trimethoxysilane followed by immobilization with the terminal trimethoxysilyl group grafting-to method). The chromatographic results are summarized as follows ... 

The free-radical addition of TFE to pentafluoroethyl iodide yields a mixture of perfluoroalkyl iodides with even-numbered fluorinated carbon chains. This is the process used to commercially manufacture the initial raw material for the fluorotelomer -based family of fluorinated substances (Fig. 3) [2, 17]. Telomeri-zation may also be used to make terminal iso- or methyl branched and/or odd number fluorinated carbon perfluoroalkyl iodides as well [2]. The process of TFE telomerization can be manipulated by controlling the process variables, reactant ratios, catalysts, etc. to obtain the desired mixture of perfluoroalkyl iodides, which can be further purified by distillation. While perfluoroalkyl iodides can be directly hydrolyzed to perfluoroalkyl carboxylate salts [29, 30], the addition of ethylene gives a more versatile synthesis intermediate, fluorotelomer iodides. These primary alkyl iodides can be transformed to alcohols, sulfonyl chlorides, olefins, thiols, (meth)acrylates, and from these into many types of fluorinated surfactants [3] (Fig. 3). The fluorotelomer-based fluorinated surfactants range includes noiuonics, anionics, cationics, amphoterics, and polymeric amphophiles. 

Both dJorofluorocarbons (CFCs) and carbon dioxide appear to be very good solvents for amorphous, low-melting fluoropolymers. Since environmental restrictions have limited the use of CFCs drastically, carbon dioxide has become a highly viable alternative solvent for the production of amorphous fluoropolymers [59]. Examples of polymerization of fluorinated monomers in a homogeneous reaction medium of SCCO2 are the polymerization of fluorinated acrylates (see, for example Refs. 59-61, fluoroalkyl-derivatized styrene [62], fluorinated vinyl and cyclic ethers [63], and the telomerization of 1,1-difluoroethylene [64]. Other options to run a... 

OEA synthesis can also be achieved by additive telomerization of cychc ethers. Typical of this method is the reaction between anhydrides and epoxides. The process takes place in the presence of the telogenes in the category of acrylic acid or of its derivatives. An example is shown in the following reaction [15] ... 

Oligocarbonateacrylate (OCA) synthesis uses, in the main, the method of condensation telomerization. In some patents issued from 1945 to 1947 [20-23] experimental results are presented that prove that carbonic acid forms oligomers containing polymerizable groups of the allylic or acrylic type and one or more carbonate groups. The production of dimethacrylic esters of carbonic acid and of glycol is demonstrated. The process develops in several stages, in the presence of acid catalysts. 

Tkatchenko and coworkers reported that cationic palladium complexes are very effective in the dimerization of methyl acrylate [53], as it has been already observed for other oligomerization and telomerization reactions... 

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