Turning experiments

These addition reactions require formation of an imino-cyclohexadiene intermediate (Fig. 13.41). In cases where the ipso substituent is a proton, tautomeriza-tion to form the substituted aniline derivative is fast, and such intermediates have not been isolated. On the other hand, in situations where the nucleophile adds to a substituted ring position, the intermediate can undergo further secondary reactions. For example Novak et al. showed that the 4-biphenylylnitrenium ion reacts with water forming the imine cyclohexadiene intermediate 74, which in turn experiences an acid-catalyzed phenyl shift reaction to 76 via 75 (Fig. 13.42). 

Boud, D., Keogh, R. cind Walker, D. (Eds) (1985). Reflection Turning Experience into Learning. Kogan Page. 

They reflect on what they learn and turn experience into insight. 

Judgment Techniques represent those techniques that attempt to turn experience, judgment, and intuition into formal forecasts. There are six popular techniques within this category ... 

The system was modeled using the one-dimensional SIN code with C-J Burn in plane and spherically diverging geometry and using the two-dimensional TDL code with C-J burn and multiple-shock Forest Fire. The HOM equation of state and Forest Fire rate constants used were identical to those used to model the PHERMEX corner turning experiments in the mid 1970 s and listed in Chapter 4. 

The design of a pulsed EPR spectrometer depends heavily on tlie required pulse lengdi and pulse power which in turn are mainly dictated by the relaxation times of tlie paramagnetic species to be studied, but also by the type of experiment perfomied. When pulses of the order of a few nanoseconds are required (either to compete... 

Figure B2.5.2. Schematic relaxation kinetics in a J-jump experiment, c measures the progress of the reaction, for example the concentration of a reaction product as a fiinction of time t (abscissa with a logaritlnnic time scale). The reaction starts at (q. (a) Simple relaxation kinetics with a single relaxation time, (b) Complex reaction mechanism with several relaxation times x.. The different relaxation times x. are given by the turning points of e as a fiinction of ln((). Adapted from [110].

The existence of anode and cathode areas can be seen by the following experiment. A few drops of phenolphthalein are added to a solution of potassium hexacyanoferrate(III) and hydrochloric acid added, drop by drop, until the solution is colourless. (The phenolphthalein turns pink due to hydrolysis of the potassium hexacyano-ferrate(III).) Drops of this solution, about 1 cm in diameter, are now placed on a sheet of freshly abraded steel when pink cathode areas and blue anode areas appear. 

Experiment 4. Choice of Solvent and Complete Recrystallisation. Students should be supplied with distilled water and with the more common organic solvents, and also with the compounds mentioned below. Taking each compound in turn they should decide, by the methods described in (i) above, which of these six solvents is the best for recrystallisation. They should then recrystallise about 5 g. of at least two of the compounds, dry the product, and whenever possible take its melting-point. 

The oxime is freely soluble in water and in most organic liquids. Recrystallise the crude dry product from a minimum of 60-80 petrol or (less suitably) cyclohexane for this purpose first determine approximately, by means of a small-scale test-tube experiment, the minimum proportion of the hot solvent required to dissolve the oxime from about 0-5 g. of the crude material. Then place the bulk of the crude product in a small (100 ml.) round-bottomed or conical flask fitted with a reflux water-condenser, add the required amount of the solvent and boil the mixture on a water-bath. Then turn out the gas, and quickly filter the hot mixture through a fluted filter-paper into a conical flask the sodium chloride remains on the filter, whilst the filtrate on cooling in ice-water deposits the acetoxime as colourless crystals. These, when filtered anddried (either by pressing between drying-paper or by placing in an atmospheric desiccator) have m.p. 60 . Acetoxime sublimes rather readily when exposed to the air, and rapidly when warmed or when placed in a vacuum. Hence the necessity for an atmospheric desiccator for drying purposes. 

Use the results of your integrations to answer questions a-e. Turn in the results of this experiment with a short discussion. 

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