Cyanide reactions

The cyanidation reaction proceeds under mild conditions and no special equipment is required. Stereochemistry of the product usually is the same as ia the carboaylatioa reactioa. However, ia hiadered systems stereoisomeric products may be formed (59,326). Annulation by cycHc hydroboratioa—cyanidatioa fiads appHcatioa ia the syathesis of aatural products (327,328). 

Hot spot formation witliin tlie reactor can result in catalyst breakdown or physical deterioration of tlie reactor vessel." If tlie endothermic cyanide reaction has ceased (e.g., because of poor catalyst performance), the reactor is likely to overheat. Iron is a decomposition catalyst for hydrogen cyanide and ammonia under the conditions present in the cyanide reactor, and e. posed iron surfaces in the reactor or reactor feed system can result in uncontrolled decomposition, which could in turn lead to an accidaital release by overheating and overpressure. 

Silver cyanide, reaction with alkyl halides in synthesis of iso-cyamdes, 46, 77... 

Hydrogen cyanide reactions catalysts, 6,296 Hydrogen ligands, 2, 689-711 Hydrogenolysis platinum hydride complexes synthesis, 5, 359 Hydrogen peroxide catalytic oxidation, 6, 332, 334 hydrocarbon oxidation iron catalysts, 6, 379 reduction... 

Potassium cyanide, reaction with N,N-dimethylaminomethyl ferrocene methiodide to yield ferrocenyl-acetonitrile, 40, 45... 

Sodium cyanide, reaction with chioro-trifluoroethylene to form 3-chloro-2,2,3-trifluoropropionic add, 40, 11... 

The behavior of Hg(CN)2 toward the dinuclear gold(I) amidinate complexes requires comment. In the case of the dinuclear gold(I) ylide, oxidation of the Au(I) to Au(II) resulted in the formation of a reduced mercury(O) product. Figure 1.19(a) [36]. In the mercury(II) cyanide reaction with the dinuclear gold(I) dithiophosphinate. Figure 1.19(b), the stability of the gold(I)-carbon bond compared... 

Silicon tetraisothiocyanate, reaction with 2,6-dimethylaniline to yield 2,6-diraethylphenyl thiourea, 46, 70 Silver cyanide, reaction with alkyl halides in synthesis of isocyanides, 46, 77... 

Figure 1. Phase volume corrected rate constant (ko ) phase volume ((f)) for the N-dodecylnicotinamide-cyanide reaction in (a) Brlj yE and (b) CTAB yE, Curves (c) and (d) are the ionic strength corrected Brij rate constants for Stern layer thicknesses of 4A and 2A, respectively (vide text).

It can be seen that addition of cyanide creates a new chiral centre, whereas addition of hydride does not. Therefore, cyanide reacts to give two epimeric products. We already have chirality in the rest of the digitoxose chain, so the cyanide reaction must yield two diastereoisomers. On the other hand, borohydride reduction gives just a single product. 

AF values for cyanide attack at [Fe(phen)3] +, [Fe(bipy)3] + and [Fe(4,4 -Me2bipy)3] " in water suggest a similar mechanism to base hydrolysis, with solvation effects dominant in both cases. Cyanide attack at [Fe(ttpz)2] , where ttpz is the terdentate ligand 2,3,5,6-tetrakis(2-pyridyl)pyr-azine, follows a simple second-order rate law activation parameters are comparable with those for other iron(II)-diimine plus cyanide reactions. Interferences by cyanide or edta in spectro-photometric determination of iron(II) by tptz may be due to formation of stable ternary complexes such as [Fe(2,4,6-tptz)(CN)3] (2,4,6-tptz= (66)). ... 

Addition of an alkyl nucleophile leads, due to the loss of one double bond, to a decrease of electron affinity and a concomitant negative shift of the reduction potential of about 100 to 150 mV per lost double bond. One possibility to compensate for this negative shift is the introduction of an electron-withdrawing substituent such as cyanide. Reaction of liCN or NaCN with Cjq at room temperature generates the monoadduct anion that can be quenched with various electrophiles [6]. 

The known dibromide 464 was converted in good yield to the dinitrile 465 by reaction with buffered potassium or sodium cyanide. Reaction of 2,5-dimethoxycarbonyl-3,4-dicyanomethylthiophene 465 with thionyl chloride and selenium oxychloride gave thieno[3,4-f]thiophene 466 and selenolo[3,4-f]thiophene 467, respectively (Scheme 57) <2002JOC2453>. In the case of thionyl chloride as the sulfur transfer reagent, an intermediate sulfoxide 468 must be involved, which then suffers a spontaneous base-catalyzed Pummerer reaction to give 466 in high yield. 

Spacer chain catalysts 3, 4, and 19 have been investigated under carefully controlled conditions in which mass transfer is unimportant (Table 5)80). Activity increased as chain length increased. Fig. 7 shows that catalysts 3 and 4 were more active with 17-19% RS than with 7-9% RS for cyanide reaction with 1-bromooctane (Eq. (3)) but not for the slower cyanide reaction with 1-chlorooctane (Eq. (1)). The unusual behavior in the 1-bromooctane reactions must have been due to intraparticle diffusional effects, not to intrinsic reactivity effects. The aliphatic spacer chains made the catalyst more lipophilic, and caused ion transport to become a limiting factor in the case of the 7-9 % RS catalysts. At > 30 % RS organic reactant transport was a rate limiting factor in the 1-bromooctane reations80), In contrast, the rate constants for the 1 -chlorooctane reactions were so small that they were likely limited only by intrinsic reactivity. (The rate constants were even smaller than those for the analogous reactions of 1-bromooctane and of benzyl chloride catalyzed by polystyrene-bound benzyl-... 

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