A spectrophotometric kinetic experiment illustrating consecutive reactions. The methanolysis of methyl p-nitrophenyl sulfate

Buncel, Erwin; Raoult, A.; Wiltshire, J. F.

doi:10.1021/ed051p814

Cited by 4 publications

(3 citation statements)

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“…The spectral changes observed during the course of a kinetic run are illustrated in Fig. 3 and are typical of an A -t B -t C process (13). In the early stages, before a significant amount of C has formed, the isosbestic point of 272 nm is some- what poorly defined.…”

Section: Reactions With the Hznnh3+/+h3nnh3+mentioning

confidence: 97%

Bond Scission in Sulfur Compounds. Part X. The Hydrazinolysis of Methyl p-Nitrophenyl Sulfate

Buncel¹,

Chuaqui²

1975

Can. J. Chem.

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ERWIN BUNCEL and CLAUDIO CHUAQUI. Can. J. Chem. 53, 1275Chem. 53, (1975. Reaction of methyl p-nitrophenyl sulfate with the hydrazine-hydrazine hydrochloride system in methanol gives rise to different types of behavior depending on the state of ionization of the reagent. For the H2NNH2/H2NNH3+ combination the observed reaction is conversion of methyl p-nitrophenyl sulfate to p-nitrophenyl sulfate ion (alkyl-oxygen scission). For the H2NNH3+/+H3NNH3+ combination, or with +H3NNH3+ alone, one observes the consecutive processes methyl p-nitrophenyl sulfate + p-nitrophenyl sulfate ion + p-nitrophenol (alkyl-oxygen followed by sulfur-oxygen scission). For the alkyl-oxygen scission process, i.e. nucleophilic displacement on the alkyl carbon, the observed pseudo first-order rate constant is given by the contributions of several nucleophilic species; k,,,. A method for the dissection of k,,, into the constituent terms is given. The sulfur-oxygen scission process is an acid catalyzed reaction and the measured kinetic data have been utilized for the derivation of the pK. of +H3NNH3+ in methanol. Rate data for the conversion of sodium p-nitrophenyl sulfate to p-nitrophenol in methanol containing HCI have also been determined in this connection.ERWIN BUNCEL et CLAUDIO CHUAQUI. Can. J. Chem. 53, 1275Chem. 53, (1975. La riaction du p-nitrophinyl sulfate de methyle avec le systime hydrazine -chlorhydrate d'hydrazine dans le mkthanol donne lieu a differents types de reaction dependant de I'Ctat d'ionisation du reactif. Pour la cornbinaison H2NNH2/H2NNH3 +, la reaction observte est la transformation du p-nitrophknyl sulfate de mkthyle en ion p-nitrophenyl sulfate (scission alkyle-oxygene). Pour la combinaison H 2 N N H 3 + / + H 3 N N H 3 + ou avec +H3NNH3+ seul, on observe des rkactions consecutives allant du p-nitrophknyl sulfate de methyle + I'ion p-nitrophknyl sulfate + p-nitrophenol (scission alkyle-oxygene suivie par une scission soufreoxygene). Pour le processus de scission alkyle-oxygene, i.e. le deplacement nuclCophile sur le carbone de la chaine alkyle, la constante de vitesse du pseudo premier ordre qui est observee est obtenue a partir des contributions de plusieurs espkes nucleophiles; k,,, = k,,, + kc,-IC1-1 + ~H~N N~~+ [ H~N N H~+ ] + ~H~N N H~[ H~N N H~] .Ondonne une methode pour ladissection du k,,, en ses termes constituants. Le processus de scission soufre-oxygene est une rkction acido catalyske et on a pu utiliser les valeurs cinetiques mesurkes pour dtterminer les valeurs de pK, du +H3NNH3+ dans le mkthanol. A cet effet on a aussi determine la vitesse de transformation (dans du methanol contenant du HCI) du p-nitrophknyl sulfate de sodium en p-nitrophenol.[Traduit par le journal]Methyl p-nitrophenyl sulfate is the first member of the family of mixed alkyl aryl sulfates to be subjected to intensive investigation. This particular substrate offers several possible electrophilic centers in its reactions with nucleophiles: the alkyl carbon, the sulfonyl sulfur, and the aryl carbon. So far we have reported on ...

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Section: Reactions With the Hznnh3+/+h3nnh3+mentioning

confidence: 97%

Bond Scission in Sulfur Compounds. Part X. The Hydrazinolysis of Methyl p-Nitrophenyl Sulfate

Buncel¹,

Chuaqui²

1975

Can. J. Chem.

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“…CH3CH(OMe)(OEt), and CH3CH(OMe)2, respectively. The kinetic equations which represent the reactions in (3) may be written dX/dt = -kiX +£-,Y (4) dY/d( = ktX -(k-i + k2)Y + fc_2Z (5) dZ/dt = k2Y -k--2Z (6) Although these equations have been solved (4), the solution is extremely difficult and the resulting expressions very complex. In practice, several assumptions have to be made before the experimental data can be analyzed.…”

Section: Methanolysis Of Acetalmentioning

confidence: 99%

Analog computer simulation of the methanolysis of acetal

Giachino¹

1978

J. Chem. Educ.

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The use of analog computers to obtain the solutions of differential equations such as those encountered in chemical kinetics and quantum mechanics is becoming more common in chemistry, and several articles have appeared in this Journal (1) on the subject. Most of these applications have dealt with general rather than specific problems, and often the computer has been programmed (i.e., ''patched") by the instructor and used as a black box by the students. Although solutions to general problems are certainly very useful, students will appreciate the power of an analog computer more if it is also used on a problem with which they are familiar. The

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“…The modern spectrophotometer is one of the most basic and widely used instruments in analytical chemistry. Many undergraduate experiments using a spectrophotometer have been described in this Journal, such as quantitative determinations (1, 2), identification of compounds (3,4), simple kinetics experiments (5)(6)(7), kinetics experiments including spectra of products or intermediates (8,9), structural studies (10,11), equilibrium and thermodynamic experiments (12,13), and spectrophotometric titrations (14). Other exercises have been described which introduce students to the operation of a spectrophotometer (15,2).…”

mentioning

confidence: 99%

Determination of a performance parameters of a spectrophotometer: An advanced analytic experiment.

Cope¹

1978

J. Chem. Educ.

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A spectrophotometric kinetic experiment illustrating consecutive reactions. The methanolysis of methyl p-nitrophenyl sulfate

Cited by 4 publications

References 4 publications

Bond Scission in Sulfur Compounds. Part X. The Hydrazinolysis of Methyl p-Nitrophenyl Sulfate

Bond Scission in Sulfur Compounds. Part X. The Hydrazinolysis of Methyl p-Nitrophenyl Sulfate

Analog computer simulation of the methanolysis of acetal

Determination of a performance parameters of a spectrophotometer: An advanced analytic experiment.

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