Nitrogen-lithium bond

Polymerization and Copolymerization with Lithium—Nitrogen-Bonded Initiator... 

From the above studies, it is clear that a copolymer of butadiene and styrene can be prepared from lithium-nitrogen bond initiators. The styrene content of the copolymer is highly dependent on the type of initiator and the polymerization conversion. These lithium-nitrogen bond initiators do not yield a randomized copolymer even with the presence of built-in polar modifier. This may be due to the heterogeneous nature of the initiator. In order to understand the mechanism of copolymerization with lithium-nitrogen bonded initiator. More work along these lines is needed. 

Similar conclusions are reached for the distribution of electron density in the isomeric adduct 101, where the carbon atoms adjacent to the reaction center are shifted upheld with respect to the corresponding 1,4-dihydropyridazine. Somewhat higher shielding is found for the C-5 atom (8.0 ppm) than for C-3 (3.7 ppm), but in either position the electron density appears to be appreciably lower than for C-4 in adduct 100. Such differences are presumably to be related to the nature of the lithium-nitrogen bond, but clearly to a hrst approximation all the adducts from diazines and phenyllithium can be described as undissociated species, whether that bond is ionized or strongly polar covalent. 

Hydrazones treated with alkalis decompose to nitrogen and hydrocarbons [845, 923] Woljf-Kizhner reduction) (p. 34), and p-toluenesulfonylhydra-zones are reduced to hydrocarbons by lithium aluminum hydride [812], sodium borohydride [785] or sodium cyanoborohydride [813]. Titanium trichloride hy-drogenolyzes the nitrogen-nitrogen bond in phenylhydrazones and forms amines and ketimines which are hydrolyzed to the parent ketones. Thus 2,4-dinitrophenylhydrazone of cycloheptanone afforded cycloheptanone in 90% yield [202]. 

The only example of nitrogen-nitrogen bond cleavage promoted by lithium and a catalytic amount of DTBB (10%) in THF at room temperature was performed with alkyl and aryl azides 87. After hydrolysis, the corresponding primary amides 88 were isolated (Scheme 37). ... 

Until recently, the synthesis of ionic/covalent nitrides was relatively unexplored except for the pioneering work of Juza on ternary lithium nitrides.11 However, within the last decade, several groups have begun to explore ternary nitride systems, many of which have relied on the inductive effect. The inductive effect is based on the donation of electron density from an electropositive element to an adjacent metal-nitrogen bond, thereby increasing the covalency and stability of that bond and of the nitride material itself. The success of this method is illustrated by the fact that almost all of the known ionic/covalent ternary nitrides contain electropositive elements. Only recently has a small number of transition metal ternary nitrides been synthesized in the absence of the inductive effect at moderate temperatures, by taking advantage of low temperature techniques, such as the ammonolysis of oxide precursors and metathesis reactions.6,12-17... 

The azoles and benzazoles contain the hetero-nitrogen bonded in the same manner as pyridine, and thus reduction of the bases with lithium aluminum hydride or the salts with sodium borohydride... 

A study35,36 concerning the ambidentity of the lithium salts of imines resulted in the discovery that the lithium is bonded to the nitrogen, e.g. compare 8 (equation 3). However, the evolution of the products on the carbon or nitrogen is influenced by the nature of the electrophile reactants like methyl iodide that ionize with difficulty will form a six-centered transition state 21 where the C-alkylation product will be evolved after elimination of lithium iodide. In the same way, the intermediate in aldol condensation is 22. 

Several brief preliminary reports in the literature indicate the formation of products from nitric oxide containing nitrogen-nitrogen bonds. Lithium aluminum hydride plus nitric oxide is reported to give rise to hyponitrite ion (17), Grignard reagents (27) and aluminum triethyl (3), when reacted with NO, give rise to intermediates which upon hydrolysis produce nitrosated alkyl-substituted hydroxyl-amines. These materials are reported to be unstable and evidence for their existence is indirect. If these products are indeed formed, the reactions can be easily incorporated into the BNO scheme. 

In a number of cases, the addition of lithium reagents to ketone mono- and di-tosylhydrazones can be improved by the inclusion of Cu which activates the carbon-nitrogen bond toward nucleophilic addition. However, the formation of complex product mixtures with many ketone tosylhydrawnes limits its synthetic utility. ... 

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