Student Exercises

1 Using Table 1.4, calculate the exact mass for the above compounds (a-o). 

3 Write the structure for the molecular ion for each compound (a-o) showing, when possible, the location of the radical cation. 

4 Predict three major fragmentation/rearrangement pathways for the above compounds. For each pathway, cite the rule from Section 1.5.4 that supports your prediction. 

5 For each fragmentation/rearrangement pathway from exercise 1.4, show a detailed mechanism using either single barbed or double barbed arrows as appropriate. 

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For a complete description of WebSpectra see pp 118-120 of the January 2001 issue of the Journal of Chemical Education Using the SDBS as the basis for student exercises in organic spec troscopy is described in the September 2001 issue of the Journal of Chemical Education pp 1208-1209... 

The separate parts in the school chemistry textbooks are accompanied by student-exercises that mainly aim to train the students ability to reproduce the chemical knowledge presented. It takes quite a large number of chemistry lessons before a student will come to a point where the new chemical knowledge may be related to society and the everyday world. Only some students start to ask about nitrates and environmental problems while climbing the ladder. Mary never make such a coimection. According to the common ciuriculum philosophy that students first need to climb the ladder , it takes a long climb for students to see the relevance to societal themes in fact it is impossible within the (time) limits of the school chemistry curriculum. 

The first strategy is to rmdertake a superficial scan of mainstream textbooks that everyday situations have been connected to cormnon school chemistry textbooks. For example, student-exercises may contain informatiorr, about contaminants in a river such as lead salts, about acid-base indicators in plants or about food additives for the preservation of wine. However, implicit confusion may (and frequently will) occur when the textbook and the teacher aim at reaching the right answer, for example the correct calculation of the concentration of an additive in gram per litre or parts per million (ppm). Students may still pose questions such as How many glasses of wine can I drink before 1 will get sick What is the effect of alcohol on my body Why is the addition of sulphite to wine important Is the same fact tme for red wine Or even further Shouldn t the government prohibit the addition of sulphite In this way students can become personally involved in subjects that can be related to their learning of chemical substances, and even to atoms and molecules. But, the student-activities in mainstream school chemistry textbooks often are not focused on this type of involvement they do not put emphasis in the curriculum on personal, socio-scientific and ethical questions that are relevant to students lives and society. 

A good student exercise is to draw a graph oiy = a ln ior a fixed a, You ll see the same kind of increase in y followed by a decrease as you do for hyperspheres. Draw a 3-D plot showing the relationship between sphere hypervolume, dimension, and radius. 

It is an instructive student exercise to compare plots of Vlj and VMorse for fixed s and RQ, noting the dramatic differences at both large and small R despite matching bond length and strength. One size does not fit all ... 

Cognate preparation. Reduction of 2,4-dinitrophenol. It is an interesting student exercise to carry out the reduction of 2,4-dinitrophenol under the conditions described above for m-dinitrobenzene. The spectroscopic features of the isolated and purified product, together with the melting point, in comparison with the literature values for the possible isomers, should enable a deduction to be made on the regioselectivity of the reaction. 

The DEPT sequence (distortion enhancement by polarization transfer) has developed into the preferred procedure for determining the number of protons directly attached to the individual 13C nucleus. The DEPT experiment can be done in a reasonable time and on small samples in fact it is several times more sensitive than the usual 13C procedure. DEPT is now routine in many laboratories and is widely used in the Student Exercises in this textbook. The novel feature in the DEPT sequence is a variable proton pulse angle 9 (see Figure 4.11) that is set at 90° for one subspectrum, and 135° for the other separate experiment. 

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