The reactivity of cyclic germoxycarbene complexes of manganese and rhenium towards nucleophiles

1976 ◽  
Vol 54 (16) ◽  
pp. 2557-2562 ◽  
Author(s):  
M. J. Webb ◽  
W. A. G. Graham
Keyword(s):  
Infrared Spectra ◽  
Empirical Formula ◽  
Sodium Methoxide ◽  
Lithium Bromide ◽  
Subsequent Treatment ◽  
Nucleophilic Attack ◽  
Tetraethylammonium Bromide ◽  
Carbene Complexes ◽  
Methoxide Ion

Several acylate salts and noncyclic carbene complexes of manganese and rhenium, containing organogermanium ligands, have been prepared via the reactions of the cyclic germoxycarbene complexes of empirical formula Ph2GeM(CO)4COMe (M = Mn, Re) with the nucleophiles methyllithium or methoxide ion. In each case the observed product could be rationalized in terms of nucleophilic attack at germanium. Treatment of Ph2GeRe(CO)4COMe with methyllithium, followed by ethylation with aqueous Et3OBF4, afforded cis-Ph2MeGeRe(CO)4C(OEt)Me. The manganese analog of this product could be obtained if excess methyllithium were used in the first step. The use of a deficit of methyllithium, however, followed by ethylation, yielded cis-Ph2FGeMn(CO)4C(OEt)Me. Solution infrared spectra have indicated that lithium methoxide and lithium bromide impurities in the methyllithium are involved in this reaction. The reaction of Ph2GeMn(CO)4COMe with sodium methoxide is presumed to involve nucleophilic attack at germanium to give a methoxygermanium species. Subsequent treatment with aqueous tetraethylammonium bromide gave the hydroxygermanium complex, [cis-Ph2(HO)GeMn(CO)4C(O)Me][Et4N]. Ethylation of the same species with aqueous Et3OBF4 afforded cis-Ph2FGeMn(CO)4C(OEt)Me.

Mechanisms of Nucleophilic Attack at Carbon-Nitrogen Double Bonds. The Reaction of Benzohydrazonoyl Compounds With Methoxide Ion

1995 ◽  
Vol 48 (12) ◽  
pp. 2041 ◽  
Author(s):  
JE Rowe ◽  
DA Papanelopoulos
Keyword(s):  
Nucleophilic Attack ◽  
Rate Data ◽  
Double Bonds ◽  
Elimination Mechanism ◽  
Methoxide Ion

Rate data for the reaction of a number of benzohydrazonoyl compounds with methoxide ion are reported. The stereochemistry of the products was determined by h.p.l.c. The mechanism of the reactions and the stereochemistry of the products resulting from an addition-elimination mechanism are discussed.

Quaternary Nitrogen Heterocycles. VII. Reactions of some Tricyclic Heteroaromatic Cations in Basic Solutions

1974 ◽  
Vol 52 (6) ◽  
pp. 981-987 ◽  
Author(s):  
John W. Bunting ◽  
William G. Meathrel
Keyword(s):  
Nitrogen Heterocycles ◽  
Resonance Energy ◽  
Nucleophilic Attack ◽  
Quaternary Nitrogen ◽  
Basic Solutions ◽  
Methoxide Ion

Pseudobase formation and methoxide ion addition have been investigated spectroscopically for some N-methylacridinium, -phenanthridinium, and -benzoquinolinium cations. Susceptibility to nucleophilic attack decreases in the order 10-methylacridinium (pKROH = 9.86) > 5-methylphenanthridinium (pKROH = 11.94) > 1-methyl-5,6-benzoquinolinium ≈ 1-methyl-7,8-benzoquinolinium (pKROH &([a-z]+); 14). A qualitative correlation of pKROH with loss of resonance energy upon pseudobase formation is shown to exist. For the 9,10-dimethylacridinium cation, the C-9 pseudobase (or methoxide adduct) is the kinetically preferred product in basic solutions but this is subsequently converted to the thermodynamically more stable anhydrobase. With the corresponding 9-ethyl- and 9-benzyl-10-methylacridinium cations, the pseudobase, rather than the anhydrobase, seems to predominate at equilibrium.

Kinetic Studies of the Reaction of Picryl Chloride with Sodium Methoxide in Methanol

1974 ◽  
Vol 52 (1) ◽  
pp. 18-24 ◽  
Author(s):  
Leong Huat Gan ◽  
Albert Richard Norris
Keyword(s):  
Kinetic Parameters ◽  
Sodium Methoxide ◽  
Kinetic Studies ◽  
Analogous Reaction ◽  
Picryl Chloride ◽  
Methoxide Ion ◽  
Thermodynamic And Kinetic Parameters

Picryl chloride reacts rapidly with methoxide ion in methanol to form a σ-complex containing methoxide ion attached to the C-3 position of the picryl chloride. Thermodynamic and kinetic parameters characterizing this reaction are presented and compared with corresponding parameters for the analogous reaction of methoxide ion and 2,4,6-trinitroanisole in methanol. Details concerning the much slower formation of the σ-complex containing methoxide ion added to the C-1 position of picryl chloride are also presented.

Trifluoromethylsulfonyl aryl derivatives: competitive nucleophilic attack at an aromatic carbon and at the sulfur atom of an aromatic SO2CF3 group

1980 ◽  
Vol 58 (1) ◽  
pp. 65-71 ◽  
Author(s):  
François Terrier ◽  
Jean Morel ◽  
Marie-José Pouet ◽  
Marie-Paule Simonnin
Keyword(s):  
Nitro Group ◽  
Sulfur Atom ◽  
Negative Charge ◽  
Chemical Shifts ◽  
Nucleophilic Attack ◽  
Aromatic Carbon ◽  
Methoxide Ion ◽  
Aryl Methyl

The reaction of methoxide ion with 2-nitro-4-trifluoromethylsulfonylanisole, 4-nitro-2-triftuoromethylsulfonylanisole and 2,4- bis(trifluoromethylsulfonyl)anisole in DMSO has been studied by 1H and 19F nmr. Evidence for the transient formation of gem-dimethoxy σ-adducts arising from nucleophilic attack at the aromatic C1 carbon is given. Concurrent methoxide ion attack occurs at the sulfur atom of the SO2CF3 group to give the aryl methyl sulfonates ArSO3CH3, which are slowly converted into aryl sulfonates ArSO3−. The 1H chemical shifts of the anisoles are consistent with a greater electron-withdrawing effect of the SO2CF3 group compared to the nitro group. In contrast, a 4-nitro group appears to be more efficient than a 4-SO2CF3 group in delocalizing the negative charge of the σ-adducts.

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