Mechanism of ester aminolyses in aprotic solvents

Menger, F. M.; Smith, J. L.

doi:10.1021/ja00766a027

Cited by 206 publications

(87 citation statements)

References 3 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Similar results were reported for the reaction of 4-chlorophenyl acetates with pyrrolidine and of phenylphenoxy acetate with benzylamines in CH 3 CN. 8,9 For the aminolysis of 4-nitrophenylacetate and triphenylmethylsulfenyl chloride 10 the k 3 term was not observed, but both k 2 and k 3 terms were observed for chloro-and dichloroacetates in CH 3 CN. 11 These results indicate that a strong electron acceptor in aryl moiety requires general base catalysis in aprotic solvent.…”

Section: Methodsmentioning

confidence: 99%

Aminolysis of 4-Nitrobenzenesulfenyl Chloride

Lee¹,

Lee²,

Koo³

2011

Bulletin of the Korean Chemical Society

View full text Add to dashboard Cite

Nucleophilic substitution reactions at a dicoordinated sulfur compound take place through a bimolecular mechanism 1,2 as well as a tricoordinated sulfur compound. [3][4][5] These reactions are well known to proceed through a stepwise mechanism with a hypervalent sulfur species(sulfuranide) as an intermediate or through a single step with synchronous bond formation and breaking (S N 2 type mechanism) as shown in Scheme 1.The tool of criterion for the mechanism of nucleophilic substitution reactions has been most frequently used Bronsted and Hammett eq. For example, a break or curvature in Bronsted plot has often been observed for the aminolysis of ester with good leaving group. 6,7 Nonlinear free energy relationships have been often interperated as a change of a rate determining step for a stepwise mechanism, while a linear Bronsted plot suggests no change in mechanism.The studies on nucleophilic substitution reactions of a dicoordinated sulfur compound are very rare in comparison with those of a tricoordinated or tetracoordinated sulfur compounds. The authors have performed the kinetic studies on the reaction of 4-nitrobenzenesulfenyl chloride with substituted (X)benzylamines in DMSO at 25 o C to gain further information into the aminolysis mechanism of a dicoordinated sulfur compound. Results and DiscussionThe reaction of 4-nitrobenzenesulfenyl chloride with benzylamines in DMSO obeyed pseudo-first order kinetics under large excess amine concentration. Pseudo-first-order rate constant (k obsd ) was obtained from the slope of the plot of ln(λ−λ t ) vs time and listed in Table 1.The k obsd value increases with increasing concentration of amine, but it shows the upward curvature at higher concentration of amine as shown in Figure 1. Therefore, the k obsd can be given by Eq. (1), where k o is the solvolytic rate constant, and k 2 , k 3 are the second order and the third order rate constants with X-benzylamine, respectively. When the reactions take place as described in Eq. (1), involving the term of general base catalysis, the plot of(2), should be linear, and the expected linear plot was obtained as seen in Figure 2. • ■ Scheme 1

show abstract

Section: Methodsmentioning

confidence: 99%

Aminolysis of 4-Nitrobenzenesulfenyl Chloride

Lee¹,

Lee²,

Koo³

2011

Bulletin of the Korean Chemical Society

View full text Add to dashboard Cite

show abstract

“…The large negative S # value indicates a rigid transition state or great participation of methanol molecules in the activated complex, Table 1. Menger and Smith (1972) suggested that the leaving group departs slowly in either a concerted mechanism, Scheme 1, pathway (a) or a stepwise mechanism, Scheme 1, pathway (b). They chose to favor a stepwise mechanism.…”

Section: Reactions Of 24-dinitrophenyl Acetate 1 With Hydrazine In Mmentioning

confidence: 99%

Nucleophilic Substitution Reactions of 2,4-Dinitrobenzene Derivatives with Hydrazine: Leaving Group and Solvent Effects

Ibrahim¹,

Abdel-Reheem²,

Khattab³

et al. 2013

IJC

View full text Add to dashboard Cite

The hydrazinolysis of 2,4-dinitrophenyl acetate in methanol proceed exclusively through acyl-oxygen scission by a concerted mechanism. The reaction of 1-chloro-2,4-dinitrobenzene with hydrazine in methanol, acetonitrile and dimethyl sulfoxide undergo uncatalyzed substitution and the formation of the zwitterionic intermediate is the rate-determining step. While 2,4-dinitrobenzene derivatives 1, 2, 3, 4, 5a-i, 6 with hydrazine in DMSO undergo uncatalyzed substitution and the departure of the leaving group is the rate-determining step. The process depends on the basicity of the leaving group and its steric hindrance as well as the possible intramolecular hydrogen bond in the transition state. The reactivity of compounds 5a-i depends on the substituent of the thioaryl ring while the small ρ Y value is due to the sulfides existing preferentially in the skew conformation. The small β lg value (-0.18, r = 0.99) indicated that the reaction of sulfides with hydrazine proceeds with advanced bond formation to the nucleophile and the bond cleavage proceed in a slow extent in the transition state.

show abstract

“…In this paper we report our results on the aminolysis of three phosphinate esters (3)(4)(5) as well as on p-nitrophenyl diphenylphosphinothionate (6), -phosphinothioate (7), and -phosphinodithioate (8). Compounds 4-8 were studied with butylamine only but ester 3 was studied with butylamine, a series of secondary amines, and diamines.…”

Section: Introductionmentioning

confidence: 99%

The aminolysis of phosphinates; the kinetics and mechanism of the aminolysis of phosphinate esters in acetonitrile

Cook¹,

Daouk²,

Hajj³

et al. 1986

Can. J. Chem.

View full text Add to dashboard Cite

. J. Chem. 64, 213 (1986).The aminolysis of aryl diphenylphosphinates, p-nitrophenyl diphenylphosphinothlonate, -phosphinothioate, and -phosphinodithioate by n-butylamine, by the secondary arnines piperidine, pyrrolidine, morpholine, and dipropylamine, as well as by a series of diamines, has been studied in acetonitrile. The general reactivity order is diamines > butylamine > sec-amines.Butylaminolysis follows a two-term rate law, one first order in amine and the other second order in amine. The second order in amine term predominates. sec-Arnines and diamines follow a rate law which is first order in amlne only. Leaving group effects, solvent effects, and activation parameters support a pathway which involves rate-determining collapse of a zwitterionic pentacoordinate intermediate. Operant dans I'acCtonitrile, on a CtudiC l'aminolyse des diphCnylphosphinates d'aryles et des diphCnyl-phosphinothionate, -phosphinothioate et -phosphinodithioate de p-nitro-phCnyle par la n-butylarnine, par les amines secondaires cornrne la pipendine, la pyrrolidine, la morpholine et la dipropylamine ainsi que par une sCrie de diamines. L'ordre de rCactivitC gCnCrale est le suivant: diamines, butylamine, amines secondaires. La butylaminolyse obCit a une Cquation de vitesse impliquant deux termes, un du premier ordre en amine et un autre du deuxieme ordre en amine. Le terme du deuxikme ordre en arnine prCdomine. Les reactions avec les arnines secondaires et avec les diamines obCissent a une Cquation du premier ordre en arnine seulement. Les effets de groupements nuclCofuges et de solvants ainsi que les parametres d'activation sont en accord avec un mCcanisme rCactionnel irnpliquant une Ctape dkterminante au cours de laquelle il y a dCcomposition d'un intermkdiaire zwitteriol~ique pentacoordonnC. Dans le cas de la butylamine, cette dCcomposition est sournise a une catalyse gCnCrale des bases et, pour les diarnines, la rCaction est soumise B une catalyse gCnCrale des bases qui est intramoltculaire.[Traduit par le journal]

show abstract

Mechanism of ester aminolyses in aprotic solvents

Cited by 206 publications

References 3 publications

Aminolysis of 4-Nitrobenzenesulfenyl Chloride

Aminolysis of 4-Nitrobenzenesulfenyl Chloride

Nucleophilic Substitution Reactions of 2,4-Dinitrobenzene Derivatives with Hydrazine: Leaving Group and Solvent Effects

The aminolysis of phosphinates; the kinetics and mechanism of the aminolysis of phosphinate esters in acetonitrile

Contact Info

Product

Resources

About