This text is specifically designed to help introductory Organic Chemistry students understand the fundamental concepts covered in undergraduate organic chemistry. The purpose of this book is three-fold: to explode the misconceptions and misgivings that are prevalent regarding this vast subject, provide additional insight for students on a number of concepts essential to mastery of organic chemistry, and explore alternative learning strategies to assist the beginning organic chemistry student in applying a specialized problem solving technique which centers on structure, function and a mechanistic approach. Examples of key chemical transformations are dissected and analyzed to assist students in improving their problem-solving skills. Each chapter contains a number of additional problems and the solutions to those problems are provided at the end of each chapter.
Succeeding in Organic Chemistry
A Systematic Problem-Solving Approach to Mastering Structure, Function and MechanismBy Joseph C. SloopAuthorHouse
Copyright © 2010 Joseph C. Sloop
All right reserved.ISBN: 978-1-4520-1737-2 Contents
Chapter 1 - Studying for Success.........................................................1Chapter 2 - Fundamentals.................................................................6Chapter 3 - Drawing Chemical Structures..................................................23Chapter 4 - Stability of Carbon Compounds and Reactive Intermediates.....................31Chapter 5 - Isomerism and Stereochemistry................................................52Chapter 6 - Function of Reagents in Organic Chemistry....................................64Chapter 7 - Step-by-Step: How Reactions Occur............................................68Appendix A - Reducing Agents.............................................................125Appendix B - Oxidizing Agents............................................................128Index of Key Terms.......................................................................132Index of Chemical Species................................................................134
Chapter One
Studying for Success
1.1 Exploding the Myth
A frequent comment heard from beginning organic chemistry students is that "I'll never be able to learn this - there's too much to memorize." At least part of this statement is true - there is too much material to commit to memory. Unfortunately, many students attack organic chemistry this way, that is, they never get past the idea that memorization is the only key to success.
For those who take foreign languages, learning a foreign alphabet, numbers, grammatical rules and certain idiomatic expressions are necessary before being able to speak, read and write in that language with some degree of fluency. Much of this requires memorization. It is the continued use of these components of a language and not the fact that you memorized the rudiments that eventually leads to an understanding of how to put words together in spoken and written forms.
Organic chemistry is similar. It has a unique language students must know. So, some memorization of the lexicon early is critical. Without it, we could never get to the good part of organic chemistry - understanding how and why chemical reactions take place. Once we can speak, read and write of organic chemistry using the accepted terminology, grasping concepts that are based in that common language no longer need be just memorized - they can be understood and applied. It is the continued use of these concepts through a systematic method of working and solving problems in organic chemistry that moves the true student of organic chemistry beyond the memorization mode.
1.2 Being the Student of a Subject
The difference between simply taking a course and being a student of a subject cannot be overstated. Although on the surface these may have similar implications, e.g. grades and movement into more advanced science coursework, the road a student takes to negotiate organic chemistry will be established early. What this means is that someone learning about organic chemistry can either see this fascinating subject as the beginning of a journey to greater understanding or, as is often the case, a means to some end - another block checked on the way to graduation, preparation for postbaccalaureate studies, etc.
The truth is organic chemistry is not like the general chemistry courses that most undergraduates study. Although it is a survey of many topics in this field, it is something more important: it is the gateway and linch pin for other chemical and life science courses a student may study. Without a firm grasp of the concepts in organic chemistry, chemical engineering, biology, biochemistry, toxicology, and other advanced chemistry courses do not make as much sense as they should. Once you understand this external thread of continuity, the reason for learning organic chemistry is obvious.
In addition, an internal thread of continuity runs through organic chemistry. Think of it as a grand, unfinished play - one with many acts and scenes, tied together by the plot. There may be numerous characters, but they propel the play forward within the context of the plot. While organic chemistry contains many subjects, certain fundamental concepts of structure and function, if studied and understood early, will propel you, as a student forward toward better understanding of this subject and enable you to solve the many different types of problems you will encounter.
One last thing. Organic chemistry is, as are all sciences, a snapshot in time. As students, we must realize that new discoveries, investigations and research continually change organic chemistry. The dozens of academic journals devoted to organic chemistry produce upwards of 100,000 pages of new research results annually. This may add to the complexity of it, but it also makes clear the relevance of learning the fundamentals, so that we may apply them to new cases we may learn of later.
1.3 Studying Organic Chemistry
Now that you understand a bit more about why you want to be a student of organic chemistry, what steps can be taken to enable your success? As in every course, success in organic chemistry depends on many factors - but a few bear special discussion. These include:
* knowing and using all available study resources, * creating an effective study environment and * implementing study sessions using a review, read and practice, preview methodology. * Solving problems using a systematic approach.
Let's look at the first of these, the study resources available for your course.
Knowing and Using All Available Resources
o Frame of mind is key. While institutions choose organic chemistry texts and a variety of other resources in print or electronic media to suit the needs of the chemistry curriculum, you bring the most valuable resource to the table - your mindset. As you prepare to study, your frame of mind will determine, in large part, how well you will retain the subject material when studying. Without a positive attitude, the other reference materials will not be of much use.
o Learning is your responsibility. The teacher cannot force you to learn, you control it. How effectively you study and learn is influenced by your external surroundings and internal level of commitment - factors you determine. By the time you take organic chemistry, you have probably developed some sort of study habits, good and bad. In the end, you must be the judge of what works for you, but remain open to the idea that you may have to "unlearn" some poor study habits and replace them with better ones.
o Use your visual resources - text packages, electronic media and modeling kits. The study of organic chemistry is visually oriented. A wide variety of media is available to enhance your learning experience. Only if you explore the options can you decide what will help you the most.
More than twenty undergraduate organic chemistry texts are available and in use today. For the most part, these text packages are more than satisfactory, providing coverage of essential theory, practical reactions and discussions of how key transformations take place. In that the choice of text is made for you, your success begins with getting the most out of it.
Nowadays, many texts offer study guides (solutions manuals), electronic media (CD-ROMs), online study resources and even smart cell phone applications such as flash cards for nomenclature and stereochemistry. Your instructor will be able to point you in the direction of these. Many students never discover the wealth of information that is out there. As a student, you should not only ensure that you have access to these resources, but also explore all available materials that come with your text to get the most benefit from them.
Finally, aside from the text, there is one important item that you must have to truly be able to visualize the three-dimensional structure and nature of molecules - a molecular modeling kit. Many types of kits are available; your instructor will probably recommend that you obtain one for use during your course. Because organic chemistry is a visual science, building models of molecules helps you gain a better understanding of their three-dimensional structure. This will aid you in several ways. First you'll be better able to grasp how molecules appear in nature. Next, if you can build it, you can draw it correctly. Finally, when you begin to learn about reactions between organic molecules, models will assist you in visualizing how organic molecules can react to form products.
o Know your chemistry department and professor. You must know what resources your institution's chemistry department offers. Frequently, college chemistry departments will offer old tests, online homework assignments, problem sets and lecture notes to assist you. Nothing replaces working additional problems. Tutorial services available through your school can clarify difficulties you may have in understanding the course material.
More importantly, know your professor - they have a vested interest in your success. This means understanding what he or she thinks is important for you to know. Usually that is provided for you in a syllabus and in some cases lesson and course objectives. Your instructor may have this information posted online in a course website or via applications like WebCT or Blackboard. In addition, many instructors provide airliner videos to help guide students through difficult concepts.
Where possible, obtain copies of previous years' tests to learn the types of questions they ask. Don't be afraid to ask for assistance from your professor early when you are unsure of the material. Do not view your teacher as an impasse to your progress, but as a bridge to better understanding.
Create and Use an Effective Study Environment
Having a sound study plan that considers both your environment and study session is essential for success. Study in surroundings that are free from distractions, yet comfortable enough to enable you to focus. Noises, sights and interruptions can make studying less productive, so try to reduce those to a minimum. While soothing music playing on the Ipod may help some to focus, it's not for everyone. You must determine what works best for you. Last, gather all the materials you need to study before you begin so that you won't have to stop to find them.
Plan to study the material for the day's lesson while you are fresh and can devote sufficient time to the task. A good rule of thumb is that you should spend about 1-1 hours of quality study time for each hour of lecture. Once your environment is set, you will find your study efforts are maximized if you maintain a high level of internal commitment. Your study of organic chemistry includes how you approach both in-class lecture and out-of-class study.
Study organic chemistry using the review, read and practice, preview technique.
o Review - First, go over the last day's lesson by reviewing your lecture notes, the pictures and diagrams from the reading material for that lesson, and the problems you worked that amplify the material. Taking about 10-15 minutes to do this will help solidify important concepts emphasized by your professor during lecture and help you discover the relationship between this and the next lesson.
o Read and Practice - Once you have refreshed yourself, begin studying the upcoming lesson by reviewing the lesson outline while scanning the section of text to identify the major points. A common mistake beginning organic chemistry students often make is to read straight through the text highlighting every single passage. Rather, as you scan, consider diagrams, tables and figures first, as these are often used by authors to illustrate key concepts and trends discussed in the body of the text. Unless you understand them, you miss out on an important part of learning organic chemistry - the ability to recognize analogies that help you grasp concepts beyond the material you are presently covering. If online guides, a CD-ROM, your modeling kit or other supplementary learning aids are available to help you understand the material, this is the time to use them.
After you have gleaned the author's main points in the pictures, graphs and tables, begin critically reading the text material, to clarify those topics that you may not have understood fully, highlighting the important areas. Simultaneously, work example problems as you cover the portion of the reading that concerns them. Like diagrams and tables, authors use these problems to illustrate important points brought out in the text. Solving these problems (which usually contain the solutions) provides a check on your level of understanding. If you find your answer does not agree with the author, re-read the portion of the text that explains the concept. Also work assigned homework problems, as most professors will assign problems they believe best illustrate the lesson objectives while helping students grasp the material. If no problems are assigned, select problems that are related to the reading material for the lesson. Attempt to solve the problems on your own first, using the solutions manual only when required to help if you get stumped, and then as a final check of your progress.
In following this read and practice technique, you will have now studied the lesson three ways, by visually reviewing the graphics, by reading and by working problems. This should take about an hour. If you finish with questions, write them down to discuss during the next lecture period.
o Preview - Finally, take another 10-15 minutes, and preview the next day's lesson, focusing on the graphics. The objective here is to determine the linkage between these lessons - again that internal thread of continuity. The result is exposure to a given lesson's material on three occasions, once during the preview, again as you study that part of the text as the lesson of the day, and finally in a review.
Solve problems using a systematic approach.
Much of organic chemistry is about solving problems: drawing structures, nomenclature, predicting the products of a reaction or writing a step-by-step explanation for how molecules react. Regardless of the task, students do better when they have a strategy for solving problems. Ultimately, you must decide on the method that works best. Here are a few suggested steps that use the acronym GFPSC.
o G: Write down the Given information, draw the structures or reactions given as accurately as possible.
o F: Identify what you must Find and write it down. Make sure you answer the question that is being asked.
o P: Devise a Plan to solve the problem. What techniques, rules or guidelines do you need? Identify trends or analogous examples that may apply and help you.
o S: Solve the problem using the given information and your plan. Ensure your work is complete.
o C: Check your work for accuracy. Review all information used in your solution ensuring the data you used was what was required.
1.4 Optimizing your classroom experience.
Attendance in the classroom is paramount in organic chemistry because what is discussed in class one day will often be used at other times throughout the course - the internal thread of continuity. Sit where you can see and hear everything being presented. It is here where knowing your professor really pays off. Be observant - note what he or she emphasizes. Organic chemistry is a visual subject, so if the professor takes the time to discuss it, write something on a board, overhead or present it in a slide show, it is important enough for you to transcribe in your notes or to get a copy.
If, while in class, you have a question, ask for clarification before you depart. Students are often afraid to ask questions, but professors are generally pleased when a student shows enough interest to formulate a question. The beginning of understanding is recognizing what you don't know and resolving it.
Likewise, when the professor asks a question of the class, be bold and attempt to provide an answer. Answering questions you know has a calming and reassuring effect that puts your mind into a more effective mode for tackling more difficult questions.
1.5 Working additional problems
Once you have studied the reading materials and prepared questions that require answering, when time permits, work additional problems in the text. These are usually found at the end of the chapter. Check the problems to ensure your answers are accurate.
1.6 Seeking additional help if required
If questions remain after study and lecture on a particular concept or problem, seek additional help early. Students at all levels need a jump-start occasionally, so don't be afraid to ask.
1.7 Test Taking
Although taking your first organic chemistry test can be a major source of consternation, it need not be. If you have followed the guidelines set forth in this chapter, a two to three hour review of the major concepts covered in the chapters being tested (with problem solving) will usually be sufficient to garner a good grade. Having said that, here are a few suggestions to assist you during the actual test itself.
Don't forget your tools. Use a sharpened pencil for your test and ensure you have a good eraser. There is nothing worse than a test submitted with scratch-throughs and cross-outs. It is distressing for the instructor to grade tests that are messy. Bring your model kit. Most organic chemistry instructors will encourage you to use your kit, so have it available.
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Excerpted from Succeeding in Organic Chemistryby Joseph C. Sloop Copyright © 2010 by Joseph C. Sloop. Excerpted by permission.
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