Getting Practice

Now that we have answered all three questions, we are ready to draw the products (don t forget to draw both enantiomers that you get from syn addition)  

If you fail to ask all three questions, then you will not get the product correct. Many students fail to ask questions 2 or 3 (or sometimes both). Clearly, the answer is correct only if you get the stereochemistry and the regiochemistry correct. 

This section offers one approach for practicing predicting products For every reaction that you learn, we have already said that you should record it at the end of Chapter 8. Now we need to start a new list, right here in this chapter. Every time you learn a new reaction, you should write the reaction down using the arrows on the pages that follow, but do not show the mechanism or the product. Just show the starting compound and the reagents, like this  

As you learn more and more reactions, this list will grow. With every live new reactions, you should photocopy all of the reactions that you have recorded here. Then, start filling in the products on the photocopy. If you cannot fill them all in, go back to the end of Chapter 8 where you first recorded the reaction, and see how to answer the problem. If you did not fill out the end of Chapter 8, then look through your textbook and your class notes to determine the answer to all three questions (what kind of reaction regiochemistry and stereochemistry ). Repeat this procedure whenever you have entered five new reactions. 

Remember not to fill in the products or the mechanisms. For each reaction, just draw the starting material in front of the arrow and the reagents above the arrow. Leave the space for the product empty. You will fill in the products when you photocopy these pages  

Now photocopy this page, and try to fill in the products on your photocopied page. 

photocopy this page again, and fill in the products for every reaction on this page. 

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Now that we have established that formal charges must always be drawn and that lone pairs are usually not drawn, we need to get practice in how to see the lone pairs when they are not drawn. This is not much different from training yourself to see all the hydrogen atoms in a bond-line drawing even though they are not drawn. If you know how to count, then you should be able to figure out how many lone pairs are on an atom where the lone pairs are not drawn. 

You should get practice placing the mirror on either side (and you should notice that you get the same result whether you put the mirror on the left side or the right side). 

So let s get practice drawing intermediates. If you look closely at any step of a mechanism, you will see that the arrows tell you exactly how to draw the intermediate. Since you know how to classify every arrow into one of three categories... 

To do this, we need to make a list of reactions, but we will leave out the reagents, so that we can repeatedly photocopy the hst and get practice filling in the reagents. 

Here is where we run into a big problem. There is no way for me to give you problems that are appropriate. Every course goes at its own pace, in its own order, and with exams at different points in the course. I cannot give problems that will be perfectly appropriate for every student everywhere. So, how are we going to get practice Very simply. You are going to make your own problems, as described in the next section. 

These 10 sets of problems will familiarize you with arithmetic operations involving decimals (which are a really special kind of fraction). You use decimals every day, in dealing with money, for example. Units of measurement, such as populations, kilometers, inches, or miles are also often expressed in decimals. In this section you will get practice in working with mixed decimals, or numbers that have digits on both sides of a decimal point, and the important tool of rounding, the method for estimating decimals. 

In many cases it is easy to detect some catalytic activity of an enzyme in an organic solvent. However, in order to get practically useful reaction rates there is normally a need to design the enzyme preparation and the reaction conditions with much care and thought. Hopefully, this chapter and its references can help in this task. A more extensive collection of practical advice on this topic can be found in [75]. 

Go on fact-finding trips, not vacations. Even if you are using vacation time, take a few days and get practical. Visit the chamber of commerce, read the local newspaper, check out health care facilities, visit supermarkets and shopping malls, and attend church or synagogue. 

To do this, we need to make a list, very similar to the one we made in the previous chapter on predicting products. In the list we made last chapter, we left out the products, so that w e could repeatedly photocopy the list and fill in the products. This time, we will make a list of the same reactions, but we will leave out the reagents, so that we can repeatedly photocopy the list and get practice filling in the reagents. 

Christiansen et al. (54) applied the Naphtali-Sandholm method to natural gas mixtures. They replaced the equilibrium relationships and component vapor rates with the bubble-point equation and total liquid rate to get practically half the number of functions and variables [to iV(C + 2)]. By exclusively using the Soave-Redlich-Kwong equation of state, they were able to use analytical derivatives of revalues and enthalpies with respect to composition and temperature. To improve stability in the calculation, they limited the changes in the independent variables between trials to where each change did not exceed a preset maximum. There is a Naphtali-Sandholm method in the FraChem program of OLI Systems, Florham Park, New Jersey CHEMCAD of Coade Inc, of Houston, Texas PRO/II of Simulation Sciences of Fullerton, California and Distil-R of TECS Software, Houston, Texas. Variations of the Naphtali-Sandholm method are used in other methods such as the homotopy methods (Sec. 4,2.12) and the nonequilibrium methods (Sec. 4.2.13). 

To begin to get practice in systems analysis, start with something simple... 

The toughest test — predicting the product. The sooner you get practice the better. 

Skilled and successful underground chemists have usually taken a college level Organic Chemistry course, with lab, for at least one semester. In this lab, they get practice in distillation, extraction, and other skills involved in making methamphetamine. At the very least, they will go to a college bookstore and purchase the lab manual for the Organic Chemistry class. That book goes into some detail on how to distill, reflux, etc. 

We end this discussion with two comments. First, we note that the Nakajima-Zwanzig equation (10.100) is exact no approximations whatever were made in its derivation. Second, this identity can be used in many ways, depending on the choice of the projection operator P. The thermal projector (10.87) is a physically motivated choice. In what follows we present a detailed derivation of the quantum master equation using this projector and following steps similar to those taken above, however, we will sacrifice generality in order to get practical usable results. 

It is not yet clear if the variabilities of BR under field conditions are due to chemical instability or a lack of absorption into plant tissue. We have little information about absorption and translocation of BR in plants. However, these results suggest that formulation could be one of the important factors for getting practical field results. 

DSC analyses (Perkin-Elmer DSC-2C) of thiol/acrylate/benzopinacol systems show that polymerization can be initiated at temperatures as low as 85°C. However, the reaction is too slow at 85°C for the conformal coating application and temperatures of 100°C or higher are required to get practical heat cure times of 5 to 30 min. 

L. A. Underkofler Well, if you use 5-10% gelatinized product, you can get practically quantitative conversion to glucose. As you go higher, you begin to get a little isomaltose. If you use 30% starch paste you will probably get around 1/2%. If you use 50% glucose you will get several percent isomaltose. ... 

A second, and probably more important point is to show that, if sonochemistry is a really difficult topic from a theoretical point of view, in many cases it offers a very simple solution to synthetic problems. Provided a minimum easy-to-get practical knowledge is acquired, sonochemical methods can be used in most laboratories without the need for expensive equipment, and it is by no means a... 

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