Ligands, copper tris ethyl amine

Styrene (S, 99%, stabilized), 2-ethylhexylaciylate (EHA, 99-i-%, stabilized), copper(l) cUoride (CuCl), copper(l) bromide (CuBr, 98%) and ethyl-2-bromopropionate (99%) were purchased from Acros. 2-Bromopropionyl bromide (97%), ethylene glycol (99%), l,l,l-tris(hydroxymethyl)propane (97%), pentaerythritol (99%), 2,2 -bipyridine (bpyr, 99 +%) and N,N,N, N",N -pentamethyldiethylenetriamine (PMDETA, 99 %) were purchased from Aldrich. Tris(2-(dimethylamino)ethyl) amine (Mce-TREN) (18-19) and alkylated linear amine ligands (ALAL) (20-22) were synthesized according to literature procedures. All other solvents and chemicals were reagent grade, and were used as received. 

Typically, phosphoms-based ligands are used to complex no-copper transition metals. Whereas, nitrogen-containing ligands have been used in copper-and iron-mediated ATRP, including 1,1,4,7,10,10-Hexamethyltriethylenetetramine (HMTETA), 2,2 -bipyridine (Bipy), NJ l,N d l ,N -pentamethyldiethylenetriamine (PMDETA), and tris[2-(dimethylamino)ethyl]amine (MceTREN) [26, 27], The activation rate constants for these ligands in copper bromide mediated ATRP and the proposed reaction mechanism of copper/2,2 -bipyridine are shown in Fig. 3.5. 

An extensive review of the use of copper(I) complexes as catalysts in click azide—alkyne 3 + 2-cycloadditions has been presented. The polytriazole ligand tris(2- 4-[(dimethylamino)methyl]-l/f-l,2,3-triazol-l-yl ethyl)amine (DTEA) has... 

A parallel development was initiated by the first publications from Sawamoto and Matyjaszweski. They reported independently on the transition-metal-catalyzed polymerization of various vinyl monomers (14,15). The technique, which was termed atom transfer radical polymerization (ATRP), uses an activated alkyl halide as initiator, and a transition-metal complex in its lower oxidation state as the catalyst. Similar to the nitroxide-mediated polymerization, ATRP is based on the reversible termination of growing radicals. ATRP was developed as an extension of atom transfer radical addition (ATRA), the so-called Kharasch reaction (16). ATRP turned out to be a versatile technique for the controlled polymerization of styrene derivatives, acrylates, methacrylates, etc. Because of the use of activated alkyl halides as initiators, the introduction of functional endgroups in the polymer chain turned out to be easy (17-22). Although many different transition metals have been used in ATRP, by far the most frequently used metal is copper. Nitrogen-based ligands, eg substituted bipyridines (14), alkyl pyridinimine (Schiff s base) (23), and multidentate tertiary alkyl amines (24), are used to solubilize the metal salt and to adjust its redox potential in order to match the requirements for an ATRP catalyst. In conjunction with copper, the most powerful ligand at present is probably tris[2-(dimethylamino)ethyl)]amine (Mee-TREN) (25). 

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