Lithium Alkylamide Research Articles

Direct Defluorination and Amination of Polytetrafluoroethylene and Other Fluoropolymers by Lithium Alkylamides.

Polytetrafluoroethylene (PTFE) and, by extension, fluoropolymers are ubiquitous in science, life, and the environment as perfluoroalkyl pollutants (PFAS). In all cases, it is difficult to transform these materials due to their chemical inertness. Herein, we report a direct amination process of PTFE and some fluoropolymers such as polyvinylidene fluoride (PVDF) and Nafion by lithium alkylamide salts. Synthesizing these reactants extemporaneously between lithium metal and an aliphatic primary di- or triamine that also serves as a solvent leads to the rapid nucleophilic substitution of fluoride by an alkylamide moiety when in contact with the fluoropolymer. Moreover, lithium alkylamides dissolved in suitable solvents other than amines can react with fluoropolymers. This highly efficient one-pot process opens the way for further surface or bulk modification if needed, providing an easy, inexpensive, and fast experiment protocol on large scales.

ChemInform Abstract: Amination by Lithium Alkylamide Reagents of Ketimines Derived from 2-( Trifluoromethyl)anilines and Methyl Halophenyl Ketones and Their Cyclization Products 2-(Halophenyl)quinolin-4-amines.

Abstract The title ketimines containing a fluorine atom at position 2 of the phenyl group are efficiently cyclized under mild conditions to N -[2-(dimethylamino)ethyl]-2-(2-fluorophenyl)quinolin-4-amines by the reaction with a lithium reagent derived from N , N -dimethylethylenediamine. The facile regioselective displacement of C2-F in the presence of another fluorine atom at the phenyl group by the same reagent or N -lithio- N ′-methylpiperazide at a higher temperature is explained in terms of a complex induced proximity effect (CIPE) process. The CIPE process is operative in amination of the 2-fluorophenyl ketimines by the more reactive piperazide reagent prior cyclization to quinolines. The 2-chlorophenyl derivatives are much less reactive in the CIPE assisted amination.

Amination by lithium alkylamide reagents of ketimines derived from 2-(trifluoromethyl)anilines and methyl halophenyl ketones and their cyclization products 2-(halophenyl)quinolin-4-amines

The title ketimines containing a fluorine atom at position 2 of the phenyl group are efficiently cyclized under mild conditions to N-[2-(dimethylamino)ethyl]-2-(2-fluorophenyl)quinolin-4-amines by the reaction with a lithium reagent derived from N, N-dimethylethylenediamine. The facile regioselective displacement of C2-F in the presence of another fluorine atom at the phenyl group by the same reagent or N-lithio- N′-methylpiperazide at a higher temperature is explained in terms of a complex induced proximity effect (CIPE) process. The CIPE process is operative in amination of the 2-fluorophenyl ketimines by the more reactive piperazide reagent prior cyclization to quinolines. The 2-chlorophenyl derivatives are much less reactive in the CIPE assisted amination.

ChemInform Abstract: A Synthesis of Novel Polyamine Macrocycles with Organosilyl Groups.

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A Synthesis of Novel Polyamine Macrocycles with Organosilyl Groups

Abstract Polyamine macrocycles having organosilicon moieties were synthesized through new addition reaction of lithium alkylamide toward vinylsilane derivatives. 6-Ethyl-3,3-dimethyl-3-sila-6,9-diazaundecane in the presence of lithium alkylamide took place polyaddition reactions, consisting of diamine and organosilicon units alternatively. By increasing possibilities of intramolecular nucleophilic attack, the 9- and 18-membered polyamine macrocycles with organosilicon moieties were obtained in good yield.

Reactivity of Lithium Alkylamide toward Vinylsilane Derivatives

Abstract Kinetic studies concerning the addition reactions of lithium diethylamide (Et2NLi) to several vinylsilane derivatives, such as H2C=CH–Si(CH3)2X [X: methyl, phenyl, ethoxy, 2-(diethylamino)ethyl and vinyl], and H2C=CH–Si(CH3)2OSi(CH3)2X [X: 2-(diethylamino)ethyl and vinyl], were carried out. The reactivity of vinylsilane derivatives toward nucleophile was strongly influenced by the nature of the substituents on the Si atom. The reactivity of trimethylvinylsilane [rate constant k (trimethylvinylsilane; cHx; 50 °C) = 2.9 ± 0.2 · 10−4 dm3 mol−1 s−1] was found to be of the same order of magnitude as that of para-alkyl-substituted styrenes, such as 4-methylstyrene [k (4-methylstyrene; cHx; 50 °C) = 3.2 · 10−4 dm3 mol−1 s−1]. The reactivities of vinylsilane compounds having an aryl substituent, e.g. dimethylphenylvinylsilane [k (dimethylphenylvinylsilane; cHx; 50 °C) = 14.8 ± 0.3 · 10−4 dm3 mol−1 s−1] and dimethyldivinylsilane [k (dimethyldivinylsilane; cHx; 50 °C) = 14.8 ± 0.6 · 10−4 dm3 mol−1 s−1], were higher than that of trialkyl-substituted vinylsilane. This fact may be explained by a π-conjugation between the phenyl (or vinyl) and vinyl groups through an empty d-orbital of the Si atom. A vinylsilane compound having a 2-(dialkylamino)ethyl substituent, [2-(diethylamino)ethyl]dimethylvinylsilane, showed unique reactivity toward lithium diethylamide, indicating that the β-nitrogen atom plays an important role regarding the reactivity of the vinyl group. In the reaction between lithium diethylamide and vinylsilane having an ethoxyl group, an addition reaction to the vinyl group and a cleavage reaction of the Si–O linkage proceeded concurrently. No cleavage reaction, however, proceeded in the reaction of lithium diethylamide with vinylsilane compounds having a disiloxane linkage. 1,1,3,3-Tetramethyl-1,3-divinyldisiloxane exhibited a much higher reactivity than did the other vinylsilane compounds.

Lithium Alkylamide Catalyzed Addition Reaction of Alkylamine to Vinyl Monomers. II. Preparation and Q,e-Values of New Styrene Derivative: (S)-N-α-Methylbenzyl-3-vinylphenethylamine

Abstract The lithium alkylamide catalyzed addition reaction of α-methylbenzylamine with 1,3-divinylbenzene (m-DVB)was found to produce N-α-methylbenzyl-3-vinylphenethylamine (1:1 adduct) (m-MBVPA), which is a new styrene derivative, and 1,3-bis(N-α-phenethyl-2-aminoethyl)benzene (1:2 adduct). The specific rotation of (S)-N-α-methylbenzyl-3-vinylphenethylamine derived from the optically active (S)-α-methylbenzylamine with m-DVB was found to be [α]D6=−62.2°(c 1.46, CH3OH). The higher reactivity of 1,4-divinylbenzene (p-DVB) compared to m-DVB in this addition reaction system is ascribable to a larger conjugation of p-DVB. The vinyl group of m-MBVPA has been found to show a higher reactivity compared to that in the adduct of MBA with p-DVB. The monomer reactivity ratios and Q,e-values obtained from the radical copolymerization of m-MBVPA (M1) and styrene (M2) were r1=0.48, r2=0.70; Q1=0.62, and e1=0.24.

A Novel Route to 7-(Substituted Amino)-5,6-dihydrobenz[c]acridines

The title compounds (3) are produced in a novel, lithium alkylamide- and dialkylamide-mediated cyclization of N-(1,2,3,4-tetrahydro-1-naphthylidene)-2-trifluoromethylaniline (2). The mechanism of this unusual transformation that involves the trifluoromethyl group is discussed

Synthesis of Soluble Poly(Divinylbenzene) Through Anionic Polymerizatio

Abstract Lithium diisopropylamide (LDA), in the presence of diisopropylamine (DPA), initiates the polymerization of 1,4-, or 1,3-divinylbenzene (DVB) to form a soluble poly(divinylbenzene). Initiation was confirmed to take place by addition of an alkylamino group to the DVB molecule. The population of the triad tacticity of the soluble poly(DVB) suggests the steric course of the polymerization reaction to proceed according to Bernoullian statistics with respect to the diad placements, m and r. The chain-transfer reaction was found to take place through proton transfer from DPA to the growing chain end. A kinetic study of the reaction between lithium alkylamide and poly(DVB) was carried out for comparison with some other styrene derivatives. The second-order rate constant (k) of the reaction between lithium diethylamide and the vinyl group of poly(DVB) was 1.19 × 10−3 L·mol−1 ·s−1, which is only about one-fiftieth of that for 1,4-DVB. LDA was found to metalate the methyl group of 4-methylstyrene to form 4-vinylbenzyllithium without any side reaction. This carbanion has the structure of 10π-conjugation and is stable in the reaction system for more than 30 min. The vinylbenzyl anion is regarded as a model for the growing end of poly(DVB). On the basis of these results, the reason for formation of soluble poly(DVB) in the LDA-induced DVB polymerization is summarized as follows: (i) Relatively short life time of the growing carbanion owing to chain transfer by DPA; (ii) lower reactivity of the pendent vinyl groups of the soluble poly(DVB) compared with those of DVB monomer; and (iii) lowered reactivity of the growing carbanion, which has a stabilized 10π-conjugation.

Lithium alkylamide catalyzed addition reactions of alkylamines to vinyl monomers, 1. Selective formation of N‐α‐methylbenzyl‐4‐vinylphenethylamine

AbstractThe lithium alkylamide catalyzed addition reaction of α‐methylbenzylamine (1) with styrene was found to produce selectively N‐phenethyl‐α‐methylbenzylamine (3). Under the same reaction conditions, addition of (S)‐α‐methylbenzylamine (1′) to 1,4‐divinylbenzene (5) takes place selectively leading to the optically active novel styrene derivative, (S)‐N‐α‐methylbenzyl‐4‐vinylphenethylamine (6), in a one‐step reaction. The specific rotation was found to be [α]4D = −70,1° (c = 1,61 g/dl, in methanol). The following Q, e‐values and the monomer reactivity rations of 6(M1) and styrene (M2) were obtained: Q1 = 1,59, e1 = −1,28; r1 = 0,86, r2 = 0,92.

Molecular characterization of soluble poly(1,4‐divinylbenzene) obtained by anionic polymerization of 1,4‐divinylbenzene with lithium alkylamide as initiator

AbstractA series of soluble poly(1,4‐divinylbenzene) (PDVB) samples was prepared by anionic polymerization of 1,4‐divinylbenzene (DVB) in tetrahydrofuran with a varying amount of diisopropylamine. The dilute solution properties of the PDVB samples were examined with conventional methods including viscosimetry, sedimentation equilibrium, and light scattering measurements. The results suggest a considerable amount of long branches in soluble PDVB though not all of the pendant vinyl groups are consumed to form branches. A tree‐like model was proposed for the present system. The data were analysed quantitatively according to this model which yielded a consistent pair of values of the z‐average mean‐square radius of gyration 〈S2〉 and the intrinsic viscosity [η].

Synthesis and copolymerization of a polyamine macromer: Molecular design of a new functional graft copolymer

AbstractTo develop a new method for molecular design of functional polymers, polyamine macromers 4, 10, and 16 were synthesized by lithium alkylamide catalyzed polyaddition reactions of N,N'‐diethylethylenediamine (1), 1,4,10,13‐tetraoxa‐7,16‐diazacyclooctadecane (7), and piperazine (12) to 1,4‐divinylbenzene (2), respectively. Copolymerization of these macromers with styrene gave a new type of graft copolymers 6, 11, and 19, having polyamine grafts. Copolymerization data indicated that the length and number of graft chains could be controlled by adjusting the molecular weight of the macromer and its initial concentration in the copolymerization system. The crystallinity of 16, 19, and other macromers (17, 18) having piperazine units was discussed.

Synthesis of new monomers having a secondary amino group by lithium alkylamide catalyzed addition reactions of primary amines with 1,4‐divinylbenzene

AbstractTo establish appropriate reaction conditions for the synthesis of new monomers having a secondary amino group, a lithium alkylamide catalyzed addition reaction of primary amines with styrene was examined as the model reaction. The selectivity of N‐alkyl‐2‐phenethylamines (2) and the rate constant of the reaction were determined. On the basis of results of the model reaction, new styrene derivatives having a secondary amino group (5) were synthesized by lithium alkylamide catalyzed addition reactions of primary amines with 1,4‐divinylbenzene.

Synthesis of new monomers having a primary amino group by lithium alkylamide catalyzed addition reaction of N‐alkylethylenediamines with 1,4‐divinylbenzene

Lithium alkylamide catalyzed addition reaction of N-alkylethylenediamines (1) with styrene was examined. It was found that N-alkyl-N-(2-phenethyl)ethylenediamine (3) was formed selectively in preference to N-alkyl-N′-(2-phenethyl)ethylenediamine (4). The identification of products was carried out by 13C NMR. On the basis of the results obtained, a new type of styrene derivative having a primary amino group (6) was synthesized by lithium alkylamide catalyzed addition reaction of 1 with 1,4-divinylbenzene.