Sodium naphthalene preparation

Usually prepared on the large scale by caustic soda fusion of sodium naphthalene-1-sulphonate, but can also be obtained by high-temperature alkaline digestion of... 

Prepared commercially by NaOH fusion of sodium naphthalene-2-sulphonate. 

The addition product, C QHgNa, called naphthalenesodium or sodium naphthalene complex, may be regarded as a resonance hybrid. The ether is more than just a solvent that promotes the reaction. StabiUty of the complex depends on the presence of the ether, and sodium can be Hberated by evaporating the ether or by dilution using an indifferent solvent, such as ethyl ether. A number of ether-type solvents are effective in complex preparation, such as methyl ethyl ether, ethylene glycol dimethyl ether, dioxane, and THF. Trimethyl amine also promotes complex formation. This reaction proceeds with all alkah metals. Other aromatic compounds, eg, diphenyl, anthracene, and phenanthrene, also form sodium complexes (16,20). 

The precipitated silica (J. Crosfield Sons) was heated in vacuo at 120° for 24h. before use. Two grades of surface areas 186 and 227 m g l (BET,N2), were used during this project. Random copolymers, poly(methyl methacrylates) and polystyrene PS I were prepared by radical polymerization block polymers and the other polystyrenes were made by anionic polymerization with either sodium naphthalene or sodium a methylstyrene tetramer as initiator. The polymer compositions and molecular weights are given in Table I. 

The first reported zirconacydopentadiene was 2,3,4,5-tetraphenyl-l-zirconacyclopenta-diene (la), prepared from two molecules of diphenylacetylene and a low-valent zircono-cene [3]. The low-valent zirconocene spedes was produced by the reaction of Cp2ZrCl2 with sodium/naphthalene (Eq. 2.1). 

Cleavage of the sulfonyl esters to the parent alcohols is accomplished in yields of 60-100% by treatment of the p-toluenesulfonates with 2-6 equivalents of sodium naphthalene in tetrahydrofuran at room temperature (yields 60-100%). Sodium naphthalene is prepared by stirring sodium with an equivalent amount or a slight excess of naphthalene in tetrahydrofuran for 1 hour at room temperature under an inert gas [701]. Benzenesulfonates and bromo-benzenesulfonates are also cleaved to the parent alcohols while alkyl methanesulfonates are reduced also to hydrocarbons [701]. 

Difunctional initiators such as sodium naphthalene are useful for producing ABA, BABAB, CAB AC, and other symmetric block copolymers more efficiently by using fewer cycles of monomer additions. Difunctional initiators can also be prepared by reacting a diene such as /n-diisoprope ny I benzene or l,3-bis(l-phenylethenyl)benzene with 2 equiv of butyl-lithium. Monomer B is polymerized by a difunctional initiator followed by monomer A. A polymerizes at both ends of the B block to form an ABA triblock. BABAB or CABAC block copolymers are syntehsized by the addition of monomer B or C to the ABA living polymer. The use of a difunctional initiator is the only way to synthesize a MMA-styrene-MMA triblock polymer since MMA carbanion does not initiate styrene polymerization (except by using a coupling reaction—Sec. 5-4c). 

Monomeric styrene is destabilized as in Example 3-1 and pre-dried with calcium chlo-ride.The monomer is now allowed to stand over calcium hydride for 24 h and then distilled under reduced pressure of nitrogen into a previously flamed-out Schlenk tube. Pure 4-vinylpyridine is distilled twice over KOH pellets in vacuum.lt is then vacuum distilled under nitrogen through a column packed with Raschig rings into a previously flamed out Schlenk tube (bp 62 °C/12 torr).The closed Schlenk tubes containing the monomers are stored in a refrigerator until required.The preparation of the initiator solution (sodium naphthalene) is described in Example 3-19. 

Eor comparison, polystyrene and poly(4-vinylpyridine) are prepared by anionic polymerization with sodium naphthalene as initiator. Poly(4-vinylpyridine) precipitates from THE the mixture is poured into 200 ml of diethyl ether and the polymer filtered off.The polymer is then reprecipitated from pyridine solution into a ten-fold amount of diethyl ether and dried in vacuum. 

Polymer Preparation. Poly-para-methylstyrene (P-p-MS) was prepared by anionic polymerization in benzene at 50"C initiated by n-butyllithium (9) or in THF at 25°C initiated by sodium naphthalene (10). Polymerizations in benzene allowed preparation of more monodisperse materials than those prepared in THF since the propagation rate is slower relative to the initiation rate in the nonpolar solvent (11). Two different molecular weight materials were chlorinated (P-p-MS 1 and P-p-MS2). 

On the other hand, Ishizu et al. [58] reported the synthesis of cyclic polystyrene using interfacial condensation reaction of a/o-dibromopolyslyrcnc prepared from living polystyrene initiated with sodium naphthalene and terminated with 1,4-dibromobutane and then tetramethylenediamine as depicted in Fig. 11. The reaction was carried out in organic solvent/water to yield in more than 90%. The effect of solvent on the yield of cycUc polymer was observed, and the yield of cyclic product obtained in DMSO was higher than that in toluene. Since DMSO dissolves in both water and toluene, the reaction proceeded faster than that in toluene. 

A block copolymer of styrene and ethylene oxide has also been prepared in this manner (70, 69). a-Methyl styrene in sodium-naphthalene-tetrahydrofuran also polymerized at — 78°. The polymerization is... 

Preparation of Cellulose-Polystyrene Graft Copolymers. The polystyr-yl mono- and di-carbanions were prepared in THF at -78 °C by using n-butyl lithium and sodium naphthalene as the initiators, respectively. The carban-ions were reacted with dry carbon dioxide. The products were precipitated in methanol, filtered, washed with water and methanol, and dried. Size exclusion chromatography (SEC) established that the molecular weight of the polystyryl monocarboxylate was 6,200 and that of the polystyryl di-carboxylate 10,2000. The mono- and di-carboxylates were reacted with mesylated cellulose acetate in dimethylformamide at 75 °C for 20 h to give the cellulose-polystyrene graft copolymer (GP 1) and crosslinked cellulose-polystyrene graft copolymer (GP 2), respectively. 

Technical Observations. The process described above is the best and least expensive. There is, however, another method which is analftgous to the preparation of -naphthol. Sodium naphthalene-a-sulfonate is fused with caustic soda at 290° (not to exceed 300°). The sulfonation is carried out at 80-90°, and the product is salted out in as concentrated a solution as possible. The sulfonate can also be isolated by removing the excess acid with lime or chalk, treating with soda, and evaporating to obtain the product. The sulfonate, thus obtained, can be used in the fusion without further purification, but the resulting a-naphthol is impure. 

In the early seventies Stork and his students have shown that the intermediate enolate can be trapped by suitable electrophiles, e.g. alkyl halides, giving substituted ring-opened products. These modes of cyclopropane opening have been used for the synthesis of several natural compounds ". A tetra-activated cyclopropane is cleaved by sodium naphthalene in a preparation of a specifkally substituted semibullvalene (equation 36) . ... 

Triphenyltin sodium is prepared from triphenyltin bromide with sodium naphthalene in either tetrahydrofuran (THF) or 1-2-dimethoxyethane (DME), and MejSnNa is prepared in ethers using MejSnCl with Na naphthalene in THF, DME and THF-tetraglyme. Trimethyltin sodium is also prepared by adding MejSnBr dropwise with a heated pipet to Na in liq NHj at — 78°C under Ar. 

Antonietti et al.183 synthesized bicyclic PS homopolymers. They prepared difunctional PS initiated by sodium naphthalene in THF at —40 °C. The cycliza-... 

Disodium tetracarbonylferrate (Collman s reagent) is prepared by the reduction of Fe(CO)5 with sodium naphthalene in THF or sodium benzophenone ketyl in dioxane. Though it can be isolated as a white precipitate, it is usually used in THF or dioxane solution without isolation because of its highly air-sensitive and pyrophoric character. It is reported that the solubility of Na2[Fe(CO)4] is 7 x 10 M in THF and that it can be stored for moderate periods in an inert atmosphere in the dark [36]. X-ray crystallography of Na2[Fe(CO)4] (Fig. 10.2) shows that the C—Fe—C bond angle opposite to the sodium cations is significantly distorted (129.7°) [37]. However, this distortion is reduced for the potassium analogue [38]. 

Since Chatt and Davidson discovered C—H bond activation by reduction of RuCl2(dmpe)2 with a sodium/naphthalene system, the iron analogues have been widely investigated. Actually reductions of FeCl2(diphos)2 or FeH2(diphos)2 have played the central role in this area and FeCl2(diphos)2 can be prepared by the reaction of purified FeCl2 with diphosphine. 

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