Control of the ambident reactivity of the nitrite ion.
نویسندگان
چکیده
In previous studies, it was reported that a neighbouring equatorial ester group is essential for a good yield of nitrite-mediated triflate inversion, whereas with neighbouring benzyl ether groups or axial ester groups, mixtures are generally produced. In the present study, the origin of this difference was addressed. The ambident reactivity of the nitrite ion has been found to be the cause of the complex product formation observed, which can be controlled by a neighbouring equatorial ester group. Both N-attack and O-attack occur in the absence of the ester group, whereas O-attack is favoured in its presence. A neighbouring group assistance mechanism is proposed, in addition to steric effects, based on secondary interactions between the neighbouring ester group and the incoming nucleophile. High-level quantum mechanical calculations were carried out in order to delineate this effect. The theoretical results are in excellent agreement with experiments, and suggest a catalytic role for the neighbouring equatorial ester group.
منابع مشابه
Kinetic spectrophotometric determination of trace amounts of nitrite ion using potassium bromate-murexide mixture in acidic media
A new, simple, rapid, and cheap method for determination of trace amounts of nitrite ion is reported.Determination is based on reduction of bromate ion by nitrite ion, in the presence of murexide inacidic media. During reaction of bromate ion with nitrite ion, the reaction mixture is decolorized.The absorbance changes is then monitored spectrophotometricaly at 520 nm, at 25 °C. Dynamicrange of ...
متن کاملThe investigation of pyrocatechol electrochemical mechanism in presence of nitrite ion on platinum electrode
In this study, the electrochemical mechanism of catechol in presence and absence of nitrite ion, is investigated in phosphate buffer medium (pH=7) using platinum electrode through cyclic voltammetry method in various scan rates. Electrochemical oxidation of catechol showed how quinone has changed to o-benzoquinone and also how o-benzoquinone has reacted with nitrite ion and potential scan rate ...
متن کاملKinetic-Spectrophotometric Determination of Track Amounts of Nitrite Ion Based on Its Reduction Reaction with Thionine in Acidic Media
A simple, sensitive and rapid method for determination of trace amounts of nitrite ion in real samples is reported. The reaction is initiated by adding known volumes of a nitrite ion solution of identified concentration to acidic solutions of thionine which causes decolorizaiton of reagent with time. The absorbance changes is then monitored spectrophotometrically at l...
متن کاملDeveloped Method Application for Nitrite Ion (NO2¯ ) Analysis of Tib -186 Macrophage Like Cell Lines by Rapid Isocratic HPLC System with High Sensitive Glassy Carbon Electrochemical Detector
A rapid isocratic method of high performance liquid chromatography system (HPLC) with a glassy carbon working electrode of electrochemical detector is set up for quantitative detection of trace amount of nitrite ion (NO2¯) in aqueous protein containing cell lysate, cell media, plasma, serum, urine and other body fluids. The solid extraction reversed phase cartridges ...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- Organic & biomolecular chemistry
دوره 11 4 شماره
صفحات -
تاریخ انتشار 2013