Potassium naphthalene

Anionic polymerization of 1,4-DVB by n-BuLi leading to the microgels was also reported by Eschwey et al. [236,237]. In their experiments, n-BuLi was used at very high concentrations of 17 and 200 mol % of the monomer. Contrary to the results of Hiller and Funke [231], they observed a transition from microgel to macrogel with decreasing n-BuLi concentration. Similar results were also reported by Lutz and Rempp [238]. They used potassium naphthalene as the initiator of the 1,4-DVB polymerization and THF as the solvent. Soluble polymers could only be obtained above 33 mol % initiator, whereas below this value macrogels were obtained as by-products. 

Trineopentylstannylpotassium can be prepared from the reaction of hexaneopentyldistannane with potassium naphthaleneate, and shows. /( l9Sn-39K) coupling of 289 Hz and, in the crystal, rSnK of 354.8pm. 

The hydrolysis products of the potassium naphthalene dianion have been analyzed by proton NMR spectroscopy. As reported elsewhere (19), they agree with eq [l], whereas the ratio between the forms I and II is close to 3. 

Eq (3] takes into account the behavior of the potassium naphthalene dianion in the presence of an excess of naphthalene. 

In contrast to the potassium naphthalene dianion, EN gives rise to a dianionic species at concentrations higher than 0.03 mol.l- (Table II). Furthermore the EN dianion is unable to transfer one electron to another naphthalene molecule. These sharp differences are to be attributed to the participation of the -ethyl group in the metalation process. 

These results indicate that the naphthalene radical anion is not stable to the solvent tetrahydrofuran at room temperature on a time scale of 100 hours. Decomposition pathways are alkali metal dependent. Sodium and potassium naphthalene attack THF through a proton abstraction, cycloreversion mechanism, as previously described by Bates for the butyllithium/THF system (27). Lithium naphthalenide attacks the THF not only by the Bates mechanism but also by a nucleophilic ring opening, as is implicit in earlier high temperature work on lithium naphthalenide in THF (28) and in work on the attack of THF by tritylmagnesium bromide (29). The two smaller alkali metals, lithium and sodium, leave behind a... 

The tetrahydrofuran-insoluble residue obtained after two reactions (potassium, naphthalene, butyl iodide) contained only 45.01% carbon and 41.66% ash. The quantity of the sample was insufficient for further analysis. 

Following the method first reported for the preparation of triphenyltin sodium using Na naphthalenes trimethyltin potassium is prepared by the action of trimethyltin chloride on potassium naphthalene in tetrahydrofuran (THF), 1,2-dimethoxyethane (DME), or THF-tetraglyme mixture ... 

For the synthesis of the PEO stars, potassium naphthalene was used to generate the multifunctional initiator. The molar ratio [DVB] [K+] was less than 3 in all cases. The functionalities of the stars, as determined by LS measurements, were also rather large, ranging from 5 to 219. 

It was foimd that PS-h-PCHD block copolymers can be prepared in hydrocarbon solvents using s-BuIi as the initiator without the presence of any additive [34]. Efficient crossover reactions were obtained from either PSLi (Scheme 12 route A) or PCHDLi (Scheme 12 route B). Using potassium/naphthalene as a difunctional initiator PS-fo-PCHD-fc-PS and PCHD-fo-PS-fo-PCHD were prepared. However, the molecular weight distributions were rather broad, and side reactions were observed when copolymers with high CHD contents were required. To avoid this problem several additives were tested in order to improve the copolymerization characteristics. The best results were obtained with dimethoxyethane, DME, or... 

Acetal-terminated PEG is a modifier of CS and can be synthesised via ROP. In a recent study, 3,3-diethoxypropanol and potassium naphthalene were mixed in THF for 1 h. The purified ethylene oxide was then added to the obtained potassium... 

An acetal-terminated PEG-f -PLA copolymer, a micelle-forming polymer, was also synthesised via ROP. Firstly, 3,3-diethoxypropanol and potassium naphthalene were mixed in THF for 1 h. The purified ethylene oxide was then added to the obtained potassium 3,3-diethoxypropioxide solution and polymerisation was carried out for 48 h at 25 °C. After polymerisation, purified D,L-lactide was added to the solution. The resulting polymer was precipitated, stored in a freezer, centrifuged and then lyophilised in benzene [82]. 

A mixed solution of 0.16 of mL 2-methoxyethanol (2 mmol) and 5.6 mL (2 mmol) of a 0.35 M potassium naphthalene solution in tetrahydrofolate (THE) should be prepared. Then it should be inserted in a round bottomed-flask containing 30 mL dry hydrofolate (HE) under argon gas and stir for several minutes. 

Daxad 11KLS Potassium naphthalene-formaldehyde sulfonate dispersant, waiipaper pastes Drewsperse 470 dispersant, wash primers Disperbyk ... 

Another example is formation of graft copolymers of formaldehyde with starch, dextrin, and poly(vinyl alcohol)This procedure is also carried out in two steps. Potassium naphthalene is first reacted with the backbone polymer in dimethylsulfoxide. The formaldehyde is then introduced in gaseous form to the alkoxide solution. 

An interesting variation of this approach was recently reported by Yagci and coworkers [60], who showed that the stable TEMPO radical could undergo a one-electron redox reaction with potassium naphthalene. While the TEM PO alcoho-late thus formed does not initiate the polymerization of styrene, the polymerization of EO was readily accompHshed. PEO obtained in this way possessed TEMPO terminal units, and was subsequently used as an initiator for NMRP of styrene to produce block copolymers (Scheme 11.11). 

PEO-PIP-PEO symmetric triblock copolymers were also synthesized using sodium or potassium naphthalene as a difunctional initiator. In these samples, isoprene (IP) was polymerized first followed by the addition of ethylene oxide (EO) (Scheme 2). The final copolymers synthesized were well defined and exhibited compositional and molecular homogeneity. Due to the fact that Na or K naphthalenide is soluble in only polar solvents (e.g., THE), the microstructure of PIP was mostly 3,4-microstructure. 

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