Azide ion, alkylation

Azide ion Alkyl halide Alkyl azide Halide ion... 

Azide ion ( N=N=N ) Sodium azide IS a reagent used for carbon-nitrogen bond formation The product IS an alkyl azide... 

Azide ion ( N=N=N ) is a good nucleophile and an even weaker base than cyanide It reacts with secondary alkyl halides mainly by substitution... 

Nucleophilic substitution by azide ion on an alkyl halide (Sections 8 1 8 13) Azide ion IS a very good nucleophile and reacts with primary and secondary alkyl halides to give alkyl azides Phase transfer cata lysts accelerate the rate of reaction... 

Alkyl azides prepared by nucleophilic substitution by azide ion in primary or secondary alkyl halides are reduced to primary alkylamines by lithium aluminum hydride or by catalytic hydrogenation... 

The reactions of 3-unsubstituted iso.xazolium salts (123) with hydroxide, alkoxide, cyanide and azide ions have also been studied, and they can in general be rationalized in terms of the ketoketenimine intermediate (124). The results of these reactions are summarized below. The application of such reactions to 3-unsubstituted isoxazolium salts bearing substituents other than alkyl and aryl groups has received little attention, but 5-aminoisoxazolium salts have been studied (74CB13). 

Azide synthesis (Section 24.6) A method for preparing amines by S 2 reaction of an alkyl halide with azide ion, followed by reduction. 

Alkyl azides can be prepared by treatment of the appropriate halide with azide ion. ° Phase-transfer catalysis,ultrasound,and using reactive clays as a... 

Chlorooxadiazoles (82) react with amino compounds R NH2 (R = NH2, NHPh, alkyl, or aryl), secondary amines R R NH and azide ion to give products of nucleophilic displacement (76e), (76b), and (54i) respectively <84Mi 406-03, 90AP(323)595>. Reaction with anthranilic acid resulted in nucleophilic displacement with subsequent cyclization to oxadiazoloquinazolone (83) <84JIC436>. 

Anomalous ring expansions occur with 2-alkoxynaphtho-l,4-quinones, e.g. (202 R] = Me, R2 = H), in that attack by azide ion takes place at the more hindered carbonyl function (i.e. C-l) to give the l//-l-benzazepine-2,5-dione (203 R OH, R2 = R3 = H). In contrast, the 6-methoxy derivatives (202 R1 = alkyl R2 = MeO) suffer attack at the 4-carbonyl group to yield benzazepinedione (203 R1 = H, R2 = OMe, R3 = OH) (74CJC610). These results have led the authors to conclude that electronic as well as steric factors are important in the Schmidt reaction in determining the direction of ring expansion. 

Preparation of alkyl azides The azide ion (N3 ), a good nucleophile, can displace leaving groups from 1° and 2° alkyl halides. Alkyl azides are easily prepared from sodium or potassium azides and alkyl halides. The reaction mechanism resemhles the formation of nitrile. 

Alkyl and aryl azides are prepared by the nucleophilic displacement by azide ion on halide, sulfate, phenyldiazonium, hydroxyl, nitrate, iodoxy, alkoxy, and tosylate groups [6]. Sodium azide is the most useful and practical reagent. The use of silver azide is not necessary in most cases. Some examples from the literature [8-33] employing these methods are shown in Table I. 

Sheinker and Syrkin [21] discovered a difference between the absorption spectrum of the ion Nf- in inorganic and organic azides (salts). They concluded that the transition from- the azide ion to the azide linked with alkyl group by a covalent bond involves a change in the symmetry of the N3 group due to the change in length of the bonds N — N. 

Alkyl azides can be prepared by treatment of the appropriate halide with azide ion.939 Phase transfer catalysis940 and ultrasound941 have been used. Other leaving groups have also been used,942 for example, OH,943 OMs, OTs,944 and OAc.945 Epoxides react with NaN3, with HN3 in DMF,94 or with HN3-Et3Al947 to give 3-azido alcohols these are easily converted to aziridines,948 e.g.,... 

S-Alkylated N, N-disubstituted thioamides react with azide ion at room temperature to form what are suggested to be trisubstituted 1,5-dihydro-1,2,3,4-thia(5 v)triazoles70 [Eq. (26)]. 

Figure 5.5 Correlation between stability, measured by solvolysis rate in 80 percent aqueous acetone, and selectivity, determined by relative rate of reaction with azide ion (kN) and water (kw), for carbocations derived from alkyl chlorides. Reprinted with permission from D. J. Raber, J. M. Harris, R. E. Hall, and P. v. R. Schleyer, J. Amer. Chem. Soc., 93, 4821 (1971). Copyright by the American Chemical Society.

The +C(SH)3 cation and the radical dication derived from it have been the subject of high-level calculations.67 The ability of two adjacent sulfur atoms to stabilize cations, anions, and radicals makes these species usefiil for relating bond-breaking and electron-transfer energies.68,69 Electrophilicity parameters for the dithiocarbenium ions (27) have been worked out,70 and the stabilities of the cations (28), (29) and (30) have been estimated using PM3 calculations.71 Cation (31) can be captured by solvent or azide ion, or it may ring close to (32), which subsequently alkylates another (31) cation as shown.72... 

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