Anionic poly sulfides

In its solutions in liquid NIL. cesium is like the other alkali metals, a powerful reducing agent, so that in such solutions, titrations of cesium poly sulfide with cesium are made by eleclrumeiric methods. The solubility of cesium salts in liquid NHi increases markedly with the radius of an anion (the chloride. CsCI. 0.0227 moles per kg. the bromide. CsBr, 0.215 moles per kg. and the iodide. Csl. 5.84 moles per kg), though the values are less than for the corresponding rubidium compounds. 

In principle, deprotonation of any of the sulfanes gives poly sulfide anions. In practice, this route is not employed... 

There is a range of polysulfide dianions 8 that can be obtained by reaction of sulfur with simple sulfides, by high-temperature reaction of an alkali metal with sulfur, or by reaction of alkali metals with sulfur in liquid ammonia. Often, once formed, the anions are in equilibrium in solution, but individual anions can be complexed successfully. 8tructures of the free poly sulfide anions are shown in Figure 31. 

In the polymerization of propylene sulfide and 1,2-butylene sulfide mainly tetra-mers were observed. Cycles were formed mostly during the slow degradation process that followed rapid polymerizations. Degradation can also be induced by adding cationic initiators to polymer prepared by other mechanisms, e.g. by anionic processes. Thus, poly(trans-2,3-butene sulfide) is rapidly degraded to equimolar amounts of 3,5,6,7-tetramethyl-l,2,5-trithiacycloheptane and trans-butene 47). Poly(cis-2,3-butene sulfide) forms, however, a mixture of tetramer, trithiacycloheptane derivative and cis-butene 47 . If one is forced to use cationic processes for the synthesis of poly-sulfides, the reaction conditions should be controlled to avoid macrocyclization. If cyclic products are desired, the kinetics of their formation should be studied to determine optimum yields. 

Comparing the process of electrochemical activation to standard base-promoted addition of sulfur, the ylidene sulfur adduct 12 is formed by addition of a S -cyanomethyl anion onto t ano group (Scheme 9), while in the previous version the poly sulfide-like anion affects the methylene group of the a,p-unsaturated nitrile 10 (Scheme 8). However, if the activation with sulfur does not occur properly, the ylidene-sulfur adduct of presumed structure 10 or 12 is not formed and the side-reaction takes place. 

Brunelle, in Chapter 5, has provided a solution to the problem of quaternary ammonium catalysts being unstable at elevated temperatures in the presence of highly nucleophilic anions. He found that catalysts based on p-dialkylaminopyridinium salts are approximately one hundred times more stable than simple tetraalkylammonium salts and are useful even up to temperatures of 180 C. Especially valuable is the fact that under these conditions a variety of nucleophilic displacement reactions on aryl halides occurs, making possible the economical commercial synthesis of otherwise difficulty available poly aryl ethers and sulfides. 

Examples of organometallic polymers containing both phosphorus atoms and transition metals in the backbone include polyferrocenylphosphines 8 (and the corresponding phosphine sulfides 9), which are accessible via the thermal ROP of phosphorus-bridged [1] ferrocenophanes [16,17]. Polymers of this type have been previously prepared by condensation routes and the catalytic potential of some of their transition metal derivatives has already been noted [18]. Living anionic ROP of phosphorus-bridged [l]ferrocenophanes has recently been demonstrated and provides a route to block copolymers such as 10 (PI = poly-isoprene) [19] ... 

Scheme 2.16 displays the thermal ROP of a number of phosphorous-bridged ferrocenophanes, resulting in the isolation of phosphorus(III)- and (V)-containing polymers 59a-c.115 Reaction of poly(ferrocenylphosphines) 59a-c with elemental sulfur generated poly(ferrocenylphosphine sulfides) 60a-c. Polymers 60a-c could not be directly prepared from thermal ROP of phosphine sulfide-bridged ferrocenophanes due to partial decomposition of the products. However, ferro-cenophane 58a polymerized via anionic ROP and reacted with sulfur.116 The resultant polymers had Mn = 3600-32,000 for monomer-catalyst ratios that were varied from 11 1 to 100 1. 

A number of poly(dimethylsiloxane) and poly(ferrocenylsilane) copolymers have been prepared using thermal, anionic, and transition metal catalyzed ROP.97,98,121,124-131 Manners et al.132 described the ring-opening of [l]thia- and [l]selenaferrocenophanes using anionic initiators. Electrochemical studies of poly(ferrocenyl sulfide)s prepared by these methods elicited two reversible oxidation processes, indicating that strong Fe-Fe interactions exist in the polymers. 

The halogen functional polymer can react with a thiol by nucleophilic reaction, resulting in a polymeric thioether and a hydrogen halide. The latter is trapped by a basic additive, preventing a reverse reaction. Snijder et al. [135] used this technique to modify the end group of poly( -butyl acrylate) into a hydroxy-functional polymer. With 2-mercaptoethanol, the yield of functionalization was higher with the addition of 1,4-diazabicyclo[2,2,2]octane (DABCO) to the reaction mixture. The addition of DABCO allows for the formation of a sulfide anion, which is a stronger nucleophile. They studied this... 

Modification of the polystyryl anion was also necessary for the preparation of block copolymers with living cationic poly(l -/-butylaziridine). In the absence of modification only a mixture of homopolymers was obtained. Thus, the carbanion was first converted with propylene sulfide to the thiolate anion 126) which was then coupled with the living aziridinium cation ... 

Beryllium complexes, 3 amines, 7 anionic, 10 hydrates, 6 phthalocyanine, 59 poly carboxylic acid, 33 Schiff bases, 28 Beryllium dichloride ether complexes, 8 Beryllium difluoride ammine complexes, 7 Beryllium dihalides sulfide complexes, 10 Beryllium halides amine complexes, 8 ammonia complexes, 7 carbonyl complexes, 9 Beryllium nitrate basic, 32... 

PREPARATIVE TECHNIQUE Poly(propylene sulfide) can be prepared by ring-opening polymerization, using anionic, cationic, and coordinate catalyst. Anionic and cationic systems give an amorphous atactic polymer, while coordinate catalytic system, such as cadmium salts, give an isotactic or crystalline polymer. ... 

Anionic and Cationic Polymerizations o Radical Polymerization Advances o Coordination Polymerizations 0 Step-Growth Polymerization Advances 0 Synthesis of Tactic Polymers o Stereoblock Copolymers o Dispersion Polymerizations o Cellulosic Graft Copolymers o Diels-Alder Polymer Forming Reactions o A New Path To Phenolic Resins o Nitrogen Heterocycle Polymerizations o Optically Active Polymers o Poly (Phenylene Sulfide) o Poly (Aryl Ethers) o (Poly (Aryl Ether Sulfones) o Epoxy and Isocyanate Resin Replacement o Azlactone Functionalized Oligomers o Epoxy Resin-Isocyanate Reactions o Chelating Polymers o Oxazoline Functionalized Polymers o Poly (Alkyl Methacrylates) o Macromers... 

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