Silver perchlorate initiator

A similar transformation results when trimethylsilyloxy-substituted allylic halides react with silver perchlorate in nitromethane. The resulting allylic cation gives cycloaddition reactions with dienes such as cyclopentadiene. The isolated products result from desilyla-tion of the initial adducts ... 

The first successful polymerizations were obtained in solution, with cationic initiators, under conditions typical of ring-opening polymerization. Bredereck and Hutten polymerized the perbenzyl ether and peracetate of levoglucosan, using, as initiators, various carbonium ions formed in situ from organic halides and silver perchlorates. The products were apparently not stereoregular, but were definitely poly-... 

There are some indications that silver perchlorate has initiating properties since in some unexplained cases, the large crystals detonate on slight friction in a way similar to the detonation of crystals of lead azide or silver azide (Hein [127]). 

Easily dissociable, highly polar organic compounds were used occasionally as cationic initiators. Thus, triphenyl methyl chloride (77), triphenyl methyl chloromercurate (72), alkyl, acyl, and nitronium tetra-fluoro borates (13), silver perchlorate (77, 14), lithium perchlorate (75), acetyl, benzoyl, and tert.-butyl perchlorate (16) and acetyl fluoroborate (16) were mentioned at various times as catalysts for cationically initiable monomers. 

The ABA-type block copolymers B-86 to B-88 were synthesized via termination of telechelic living poly-(THF) with sodium 2-bromoisopropionate followed by the copper-catalyzed radical polymerizations.387 A similar method has also been utilized for the synthesis of 4-arm star block polymers (arm B-82), where the transformation is done with /3-bromoacyl chloride and the hydroxyl terminal of poly(THF).388 The BAB-type block copolymers where polystyrene is the midsegment were prepared by copper-catalyzed radical polymerization of styrene from bifunctional initiators, followed by the transformation of the halogen terminal into a cationic species with silver perchlorate the resulting cation was for living cationic polymerization of THF.389 A similar transformation with Ph2I+PF6- was carried out for halogen-capped polystyrene and poly(/>methoxystyrene), and the resultant cationic species subsequently initiated cationic polymerization of cyclohexene oxide to produce... 

Silver-initiated ring cleavage of bicyclo[1.1.0]butanes in protic solvents leads predominantly to mixtures of cyclopropanes and the corresponding dienes, e.g. a mixture of the norcarane ether 32 and the corresponding homoallylic ether 33 is observed in the reaction of 2,6-dimethyl-tricyclo[4.1.0.0 ]heptane (31) with silver perchlorate. This reaction is of little practical value for the synthesis of cyclopropane derivatives from bicyclo[1.1.0]butanes. 

The initiator was prepared by reaction of the prepolymer (Table I) with silver perchlorate for three hours at 0°C in CH3N02. 

Ethylene may be converted to pol3mier of 3,100-15,000 number average molecular weight by dialkylperoxydicarbo-nate-initiated polymerization in aqueous silver perchlorate solution at 0-40 C and l-20 bar. The narrow molecular weight distribution = 2.5-3.0) suggests that... 

Xu and Pan reported on a similar system. Bromine-terminated pSt was reacted with silver perchlorate to prepare a macroinitiator for the living CROP of THF [279]. Using macroinitiators of Mj =4250 and 7890,block copolymers were synthesized with Mj =9420 to 17,450 and M = 11,860 to 32,980, respectively. The were < 1.45 in aU cases. They also prepared a pSt based macroinitiator via ATRP using a hydroxy functional bromine-based initiator which was then used as a chain transfer agent for the CROP of 1,3-dioxepane (DOP, Scheme 35) [280]. The pSt macroinitiators obtained using the CuBr/bpy catalyst system had M = 6300 (M Mj =1.18) and 11,360 (M M =1.19). The ROP of DOP, using a slow addition of monomer technique, resulted in block copolymers with M = 17,540 (M /Mn=1.43) and Mj =30,880 (M M =1.46), as determined by NMR. Con-... 

In addition to the analysis of the thermal stability of the perchloric acid organic reaction media mixtures, a procedure was worked out to determine the fate of the perchloric acid by chlorine analysis of the batch, effluent streams, etc. Preliminary analyses on selected process samples showed no tendency for perchloric acid to concentrate in recycle material and therefore build up in the reactor. A total of less than 1% of the initial charge of perchloric acid (total chlorides calculated as perchloric acid) was found in the combined recovered acid-ester and olefin fractions. Less than 1 % of the initial charge of perchloric acid was found in the finished ester. The analytical method used was an oxygen bomb decomposition, followed by titration of chlorides with 0.0liV silver nitrate, using a recording automatic titrator. The eventual fate of the perchloric acid catalyst was... 

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