Anions sequence similarities

For cationic polymerization with an acid whose anion Z is nucleophilic, initiation involves the sequence described by Eq. 7-51 plus the formation of XXIX. XXIX propagates by a sequence similar to that described by Eqs. 7-52 and 7-53 except that a growing polymer chain possesses a Z—CO— end group instead of a lactam end group. 

Sequence Similarities in Metal and Anion Binding Sites0... 

Sequences similar to the ones detailed in O Sect. 2.1 in which the anionic carbon is present at positions other than C6 have also been described such as the C4-branched lithium species derived from iodide 66 reported by Preuss and Schmidt [45] (O Scheme 13). 

The relationship between the atlantones and deodarone is obvious. One can imagine the Michael addition of water to the two activated double bonds of a-atlantone (6.93) followed by dehydration of the resultant diol to produce the ether link of deodarone (6.95). Confirmation of the structure of deodarone relied on such interconversions. The first to show the relationship between the two ketones was the great Indian natural products chemist, Sukh Dev.6 5 He carried out a sequence similar to this hypothetical scheme. The hydroxide ion is a very poor nucleophile in Michael reactions and so Sukh Dev used the hydroperoxide anion... 

The data in Table 4.9 indicate that the Gutmann acceptor numbers (AN) follow a sequence similar to Ej and Z values. There is also a close, almost linear, correlation between the heats of solvation of certain anions, e.g., chloride and Fe(CN)6", and the acceptor numbers. 

Since the sequence is also Li ) Na ) K in the ion spectrum of negative proteins and these ions bring about fairly strong complex relations in this case also, the interpretation with regard to the cation sequence in the suppression of the tricomplex flocculation is exactly the same as that described in detail above. For the anion sequence, arguing similarly as above, the ion sequence in the ion spectrum of gelatin (p. 299, Fig. 22) is to be expected. This is indeed the same as that found experimentally in the suppression of the tricomplex. 

Similar results were found by other authors who showed that electroactivity was highly dependent on the nature of the anion. In particular, the cathodic current of PPP cycled in PC was shown to increase with the anion sequence CF3S03 [Pg.262]

The transfonnation is called nucleophilic aromatic substitution. The key to its success is the presence of one or more strongly electron-withdrawing groups on the benzene ring located ortho or para to the leaving group. Such substituents stabilize an intermediate anion by resonance. In contrast with the Sn2 reaction of haloalkanes, substitution in these reactions takes place by a two-step mechanism, an addition-elimination sequence similar to the mechanism of substitution of carboxylic acid derivatives (Sections 19-7 and 20-2). 

In general, alkali salts of lactams or suitable nucleophilic agents (e.g. KOH, potassium tert-butoxide or complex hydrides) are mainly used as initiators of the PD anionic polymerization. Similar to the CL polymerizahon [96], the counterions affect polymerization activity and a similar sequence in their efficiency was identified [97]. 

Note Some of Grahame s values for and included in this table. For a common cation, the sequence of anions in order of increasing adsorption is similar to that of the Hofmeister series in coagulation studies, and it is evident that specific adsorption properties are involved. 

Methyl propiolate and pyridine give a rather unstable 2 1 molar adduct which is the 1,2-dihydropyridine (112). The reaction sequence proposed to account for its formation is identical in principle to a similar scheme proposed earlier in the acridine series (Section II,A,2) and is also supported by the observation that the 1-benzoyl-pyridinium cation with the phenylacetylide anion yields (113). ... 

The sequence (81 84) has been proposed - to account for this process which involves decomposition of the aci-nitro anion by strong acid. The a-carbonyl group presumably stabilizes the aci-salt and thus could be responsible for inhibiting the normal Nef reaction. A similar transformation has been observed in the case of a 16-nitro-17-0X0 steroid. 

The lithium salt of 2-(di-wo-propylamino)-l,2-thiaborolide with [( -Cp ) RuC1]4 or [(i -Cp )ZrCl3] yields sandwiches similar to 39 (M = Ru, ZrCl2) (OOOM4935). The same anionic ligand enters a sequence of reactions with dimethylchlorosilane, lithium cyclopentadienyl, lithium di-wo-propylamide, and zirconium(IV) chloride to give sandwich 41. 

A similar elimination in which the tin is attacked by fluoride anions (cf. the reaction of silanes with F ) has been used179 to synthesize terminal methylene compounds as in equation (75). An analogous reaction sequence using a trimethylsilyl group in place of the trialkyltin group has been published by Hsiao and Shechter180 as part of a synthesis of substituted 1,3-butadienes. 

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