2-phenylethane-, sodium

Fluorodediazoniation of 2-fluoro-2-phenylethylamines with sodium nitrite m Olah s reagent (70% anhydrous hydrogen fluoride-30% pyridine) gives high yields of 1,1-difluoro-2-phenylethanes arising from 1,2 migration of phenyl fJ] (equation 2)... 

This method is very useful for the construction of 1-substituted 3,4-dihydroisoquinolines, which if necessary can be oxidized to isoquinolines. A P-phenylethylamine (l-amino-2-phenylethane) is the starting material, and this is usually preformed by reacting an aromatic aldehyde with nitromethane in the presence of sodium methoxide, and allowing the adduct to eliminate methanol and give a P-nitrostyrene (l-nitro-2-phenylethene) (Scheme 3.17). This product is then reduced to the p-phenylethylamine, commonly by the action of lithium aluminium hydride. Once prepared, the p-phenylethylamine is reacted with an acyl chloride and a base to give the corresponding amide (R = H) and then this is cyclized to a 3,4-dihydro-isoquinoline by treatment with either phosphorus pentoxide or phosphorus oxychloride (Scheme 3.18). Finally, aromatization is accomplished by heating the 3,4-dihydroisoquinoline over palladium on charcoal. 

To a flask containing 6.9 gm (0.05 mole) of phenylethane-l,2-diol in 25 ml of chloroform is added dropwise at room temperature 5.95 gm (0.05 mole) of thionyl chloride. After the initial reaction in which hydrogen chloride is evolved, the solution is refluxed for 1 hr. The solution is cooled, washed with water, then with 2 % sodium bicarbonate solution, dried, and distilled to afford 5.7 gm (62%) b.p. 62°-64°C (0.15 mm), n 4-6 1.5421. 

Schenck and Kaizerman1 have condensed styrene oxide with sodium bisulfite, thereby obtaining only the sodium salt of 0-hydroxy- c-phenylethane sulfonic acid Eq. 2). Location of the sulfur atom on the bemylio epoxide carbon atom is consistent with the trend usually obsorved for add-catalyzed nucleophilic attack on styrene oxide. 

In the similar structure of l.l,1,2,4,4,4-heptafluoro-3-phenylbut-2-ene, the reduction with sodium borohydride takes place readily under mild conditions and both products of vinylic and allylic Sn2 displacement are obtained the relative amounts of the products can be controlled by adding triphenylphosphane to the mixture80 (Table 2). The nonfluorinated chain in Hpenta-fluorophenyl)-2-phenylethane (12) selectively activates the para C-F bond to reduction by lithium aluminum hydride, giving the monoreduced product 13 in high yield.81... 

Application of Accelerating Rate Calorimetry (ARC) in Evaluating a Reaction with a Potentially Explosive Nitro Compound. One of our process development projects required the preparation of 2-hydroxy-l-nitro-2-phenylethane via the addition of sodium methoxide to a mixture of one mole of benzaldehyde and one mole of nitromethane in methanol (Scheme 1). 

Reduction of T [l-(2-nitrophenyl)-l//-pyrrol-2-yl]sulfonyl -acetone or -1-phenylethan-l-one with sodium borohy-dride and 5% palladium on carbon, a reagent known to convert aromatic nitro compounds to hydroxylamines, triggers intramolecular interaction and gives pyrrolo[l,2- ][3,l,6]benzothiadiazocine derivatives 90 (Equation 11 <2001MI1405, 2004T8807>). This method was further successfully applied to the reductive cyclization of 2- [l-(2-nitrophenyl)-17/-pyrrol-2-yl]sulfanyl acetonitrile. 

Authentic Samples. Authentic samples of identified compounds were obtained from reliable commercial sources or synthesized by established methods. All samples were purified by GLC separation and their identities verified by mass or infrared spectrometry. 1-Nitro-3-niethylbutane and 1-nitro-2-phenylethane were synthesized according to the method of Kornblum et al.(j ) by the reactions of 1-bromo-3-methylbutane and 2-phenylethylbromide with sodium nitrite in dimethylformamlde and urea. 

As a catalyst, sodium hydride has several interesting uses. Hugel and coworkers (32,33) have shown that it is an effective hydrogenation catalyst, but its activity is restricted to those parts of the molecule with which sodium is capable of combining thus styrene is hydrogenated to phenylethane, naphthalene to tetra-hydronaphthalene, etc., at pressures above 200 pounds per square inch and temperatures above 300 °C. Kharasch and coworkers (34) have shown that sodium hydride is an excellent catalyst for the polymerization of butadiene to form nearly transparent rubbers of excellent properties. 

A more direct approach to acetylenes has been reported which utilizes phase-transfer generated tetrabutylammonium hydroxide to dehydrohalogenate a-halo-olefins or bis-dehydrohalogenate vicinal dihalides. An example of the latter is the reaction of 1,2-dibromo-l-phenylethane in pentane with 50% aqueous sodium hydroxide in the presence of tetrabutylammonium bisulfate. The product, phenylacetylene, is produced in 87% yield in less than an hour by this method (see Eq. 9.11) [27]. The advantage of this approach is apparent when one considers that in the traditional method, jS-bromostyrene (from the dehydrohalogenation and decarboxylation of cinnamic acid dibromide) is heated with KOH at over 200° and the phenylacetylene distills as formed in 67% yield [28]. 

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