Understanding Organic Chemistry

here is your guide for understanding Chemistry

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BASIC ORGANIC CHEMISTRY MENU

PROPERTIES OF ORGANIC COMPOUNDS MENU

ORGANIC MECHANISMS MENU 1

ORGANIC MECHANISMS MENU

Quizzes

five-step

 How do we study for this course?  Here is our official five-step guide for how to study for organic chemistry. 

Step 1: Remain calm and just study.  Nobody but the gifted and boring can get an A in organic chemistry without studying.  Gosh darn it, you have to commit to this class if you want a good grade.  That doesn’t mean that you need to freak out over it, but you will need to bear down and take this monster seriously. 

Step 2: Learn the language.  Organic chem is a different language for most people.  Literally.  And if you don’t know that language or are slow in its translation, you will be behind everyone else who is fluent.  Think about it this way: If your professor rattles off a long thought and uses a lot of organic terminology, how long would it take you to decipher it?  Might the professor already have moved  on to the next thought by the time you have decoded the previous one?  Make sure you know the language so you can learn the skills.

Step 3: Know the easy reactions cold.  What are the easy reactions?  SN1, E1, SN2, E2, and alkene addition are the first five that you need to know without even thinking about it.  Don’t waste time on an exam struggling through the easy reactions. 

Step 4: Learn the basic premise of organic chemistry mechanisms, which is that electrons always flow from nucleophile to electrophile.  If you can identify which is the nucleophilic site and which is the electrophilic site, you will be well on your way to figuring out the answer to that problem. 

Step 5: Do 50 billion practice problems.  And once you have done that many, try to get to 60 billion.  Do all of the problems in your textbook.  Buy or make your own flashcards.  You cannot do too many of these.  Not only will it help you to learn how to do the problems, it will also help ensure that you are not surprised by a problem you have not seen before.
 

Study less, Study smart

SUCCEEDING IN ORGANIC CHEMISTRY

SUCCEEDING IN ORGANIC CHEMISTRY

Organic chemistry is a subject in which there is a large amount of knowledge which is expanding at an ever increasing rate. At first sight learning organic chemistry might seem an impossible task. But you can learn organic chemistry and do very well in the course. The most important factors in learning organic chemistry is a willingness to work hard, a good knowledge of general chemistry (particularly chemical bonding), the ability to think logically and to reason by analogy. It is not necessary to have a good memory to do well; in fact, the less you try to memorize material, the better. What is most important is to be able to draw logical conclusions from data and to discern logical connections relating new material to information you have already seen.

Study Hints

Different people learn at different rates, but the average person should expect to spend 10 hours or more per week outside of class on this course. People learn in different ways, but below are some suggestions that students have found helpful in the past.

1. Read each chapter at least twice, once before it is covered in class. Some people find it helpful to takes notes as they read or to highlight the text.
2. . Rather than spend all day on organic chemistry, try to spend smaller amounts of time every day. You will remember more of what you have learned this way.
3.  Do all of the assigned problems and more if you have time. It does little good to read the problem and then look up the answer in the solutions manual. You can easily convince yourself that you understand the material when you really don't. However, if you've spent some time on a problem and can't find a solution, go ahead and look at the answer and then try some similar problems.
4.  Meet regu1arly with a study group. You may want to work on problems, quiz each other, discuss difficult points in the lecture or text, etc.
5.  Some people find it useful to tape the lectures and listen to them again or to recopy their notes as soon as possible after the lecture. This reinforces the material in their minds.
6.  Come to me during my office hours or at other times if you are having difficulty or wish to discuss something. I am happy to help and will try to make specific suggestions for you. Some people find tutors to work with. Note that there are few student tutors at MCC for a course like organic chemistry since almost everyone who has completed the course has moved on.
7. Particularly as we start studying organic reactions in the middle of the semester, I urge students to keep a list of reactions. I suggest doing this on index cards where you might' write the name of the reaction, an example of it and some information on reaction conditions, competing reactions, etc.
8.  Try to keep a good overview of the material and avoid getting bogged down in minor details (“the trees and forest" syndrome). It might be helpful to make diagrams for yourself.
9.  Try to keep a positive attitude and continue working when you encounter difficultie. One bad performance on an exam is not a disaster and you will have chances to recover.

Exam Strategies

The following are suggestions for taking exams in organic chemistry that should help improve your performance. You should realize that a well-constructed exam will have some questions that are very simple and straightforward, and some that are more complex and challenging. Don't get upset or frustrated when you see a problem that you don't know how to answer

1. You are allowed to bring in a sheet of paper with relevant information. Prepare this carefully by writing important reaction, formulas, concepts, etc. This can be a good way of organizing your studying for the exam.
2. Arrive early for the exam. Don't waste the first few minutes taking off your coat, getting pens and pencils, etc.
3. Read over the exam quickly and begin by answering questions you know the answer to or can figure out very quickly. Answer the question completely but don't waste time giving information that is not asked for.
4. Attempt the difficult questions only after you have finished the simpler ones.
5. The point value of each question is given on the exam. Don't waste a lot of time on a question that is worth only a few points.
6. On essay questions or questions calling for an explanation, express yourself in complete, logical thoughts and be specific.
7. If you don't understand a question or what is being asked for, ask the instructor about it during the exam.
8. If you get very nervous during exams, you might want to contact the Counseling Center and take one of their short workshops on relieving test anxiety.

basic concept

in this video he have tried to give the basic concept behind the topics of organic chemistry such as 1. Nomenclature 2. Isomerism 3. Acid 4. Base 5.

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Is Organic Chem hard ? yes ..

Here's why

1) There is a ton of vocabulary to learn.

 David Klein, author of the acclaimed book “Organic Chemistry as a Second Language“  really hit the nail on the head with that title: organic chemistry is a language unto itself. Here’s an example of some of the vocabulary we encounter within the first 5 chapters of a typical organic chemistry textbook:

• common names of a large variety of chemical compounds
• the names of all the functional groups
• all the terms to do with structure, bonding, and stereochemistry.
• in addition, everything we’re supposed to know from General Chemistry like acidity, basicity, equilibria, thermodynamics and so forth

That’s a lot of vocabulary – when you add it up, well over 100 individual terms.

2) There are a lot of symbols to learn. 

There is a rich visual language to chemistry in addition to the spoken one. Prominent examples:

• condensed formula notation and line notation
• Fischer projections, Newman projections, wedge/dash notation, cyclohexane “chair” drawings
• Arrow notation: reaction arrows (single and double) curved arrows (single and double), retrosynthesis arrows
• The symbols for various elements, including Lewis structures

On top of the vocabulary and the symbols, at the beginning of the course we cover chemical nomenclature, including numbering/naming compounds and assigning (R), (S), (E), (Z) and so on.

This is just vocabulary, grammar, and punctuation – and we haven’t even got into the actual content yet!


3) Then there are all the facts to know. 

While a rote knowledge of facts isn’t as important as it might be in a biology course, to take one example, there are still a wide range of facts that should be at our command as we make our way through the course:

• the pKa’s of different classes of molecules
• electronegativities
• solvent polarities
• a feel for the relative values of various bond strengths
• most importantly - different reaction types

4) As if that wasn’t enough, then there are all the concepts. 

This is where things start to get really hairy. While I said that knowing rote facts isn’t stressed so much on exams, knowing the trends of those facts (and understanding them) is key. 

The students who understand the concepts are the ones who do well in the course, because this is the level of understanding that is generally tested for on exams.  Here are some examples of general questions that reflect a more conceptual understanding of organic chemistry:

• how does structure affect boiling points and water solubility?
• what factors affect acidity/basicity?
• what are the factors that affect nucleophilicity and electrophilicity?
• what are the ways in which structure affects chemical reactivity?

5) There aren’t that many formulas that help to simplify things. 

Even if you have a strong distaste for math, you have to admit that formulas have their uses.  They’re enormously simplifying. For instance, it would be nice if there was a straightforward formula for nucleophilicity, since it’s one of the most important concepts in organic chemistry. Well, sorry – you’re out of luck.  We learn that iodide is more nucleophilic than fluoride, for instance, except when we’re using a polar aprotic solvent, in which case the order is reversed. It’s all these exceptions which tend to lead to frustration. Be prepared – there’s a lot of them!

6) All of these build upon each other, like a pyramid.

 Just like we have to learn vocabulary and grammar before we can have conversations, we have to learn the vocabulary and conventions before we can make sense of a lot of the facts. Furthermore, it isn’t until we’ve seen a lot of the facts in action that we start to get a handle on the concepts. The course moves very fast. Without a command of the vocabulary and conventions introduced at the beginning of the course, the facts and concepts introduced later on will be much harder to grasp – which will translate into poorer grades.

7) Finally, the sheer complexity generated by all these conventions, facts, and concepts leads to the need to learn a great number of different skills.

 By skills, I mean applications of all of these types of knowledge toward solving different problems, for example -

• naming organic compounds
• predicting products of a chemical reaction
• determining the structure of a compound given spectral data
• planning the synthesis of small molecules

Is there any other course like it? Probably not.

 Organic chemistry is in the middle ground between a fact-heavy course like biology and a highly quantitative course like physics. So you end up getting the worst of both worlds, as far as course difficulty is concerned. It’s a course that tests our memory as well as forcing us to think. And we haven’t even mentioned the labs yet, which add a whole other practical dimension to the course. Can you think of another field of study which involves so much 1) book learning 2) making decisions based on thinking through conflicting data, and 3) working with one’s hands?

The good news is that you’ve already learned something that’s even more difficult than undergraduate organic chemistry. The fact that you’re reading this means you’ve already learned English. Think about how tough English is – the huge vocabulary, all the colloquialisms,  the weird grammar that follows no clear rules, the myriad exceptions to all the rules – English drives people nuts. Being able to read, write, and speak well in English is (in my opinion, of course) a more difficult task than learning organic chemistry. It doesn’t take a genius to learn English – but it does take motivation, time, discipline, and a lot of grunt work.

In spite of everything, success in organic chemistry is a very achievable goal. It is within the average student’s power to do well in organic chemistry, given  1) motivation, 2) sufficient time, and 3) effective study strategies.

Organic Chemistry 1

Introduction

What do people think organic is? A survey was conducted to ask participants about what they thought organic meant. Most of the replies referred to organic foods, while only a few science majors said carbon compounds. Organic chemistry is the study of the structure, properties, and reactions of carbon compounds. Even though organic chemistry focuses on carbon, many organic compounds can contain hydrogen, nitrogen, oxygen, phosphorous or other elements. Carbon molecules have many different functions; they are commonly used in medicine, food, paints, and gasoline.

Carbon-containing Compounds

Organic chemistry focuses on the structure, properties, and applications of various carbon-containing molecules that make up important biological molecules such as proteins, enzymes, carbohydrates, lipids, nucleic acids, and vitamins. A number of organic compounds are found in nature such as cotton, wool, and natrual petroleum while others are purely man-made. Industries have been able to synthesize many organic compounds such as plastics, photographic film, synthethic fabrics, and pharmeceutical drugs using applications of organic chemistry.

 

Organic Foods

Many people think of organic food as the healthier alternative because they associate organic foods with no pesticides, no chemicals and are not genetically modified. That may be true because the United States Departments of Agriculture has specific standards farmers have to follow. The questions are what is the difference between organic and non-organic produce? Are organic foods more nutritional? There have not been any real evidences about whether organic foods are more nutritional than non-organic foods. There are not as many differences between organic and non-organic as one would think, people claim that they can taste the difference between the two, but taste is solely based on personal preferences. The only differences between organic and non-organic foods are the way the food were grown, they do not look as "perfect" as non-organic foods and they spoil faster.

The definition of organic is: "having properties or characteristics of living organisms" (21). It is true that organic foods were from living beings, but the fact that people are associating organic foods as: pesticide free, hormone free, and other natural processes, is not the correct perspective. "Organic" just means things from living organisms, including: organs, hair, fruits, and even seeds.

A Brief History of Organic Chemistry

The word organic comes from the term "organism", thus explaining the focus of organisms in organic chemistry. In 1770, a Swedish chemist named Torbern Bergman made an important distinction between organic and inorganic substances. In 1807, Jöns Jacob Berzelius was the first person to call components from biological sources "Organic Chemistry". Before the modernization of organic chemistry in the early 19th century, scientists had discovered major distinctions between extracts of living and non-living things. A theory called the vital force theory, or vitalism, stated that there was a force in organic molecules that inorganic molecules do not have. In 1828, Friedrich Wöhler converted ammonium cyanate (inorganic compound) into urea.  This event is considered the start of organic chemistry. Wöhler proved the vitalism theory to be incorrect because it was believed that it was not possible to make organic compounds out of inorganic compounds.

 

This animation displays how Ammonia and Cyanate combined to form Urea.

Why learn Organic Chemistry?

Organic chemistry is everywhere as every living organism contains organic compounds. Organic chemistry has many applications in medicine, biology, technology, industrial production, and business. Other applications of organic chemistry include making plastics, gasoline, detergent and plenty of other industrial products. Organic chemistry is an important aspect of our lives.

Why is Carbon so special?

Carbon has an atomic number of 6; it is a second row element in the p-block.

 

Carbon is the sixth most abundant element in the universe (24). Carbon is able to form strong polar and non-polar covalent bonds by sharing its electrons to construct long chains and various structures. Some examples of polar covalent bonds are: C-F, C-O, and C-N. Some examples of non-polar covalent bonds are: C-C and C-H. Carbon can also attach with many metallic and nonmetallic elements. When a carbon shares its electrons with hydrogens, a hydrocarbon is formed which is considered to be the simplest organic compound. A unique property of carbon is that it can form many polymers in different structures like tubes, spheres, rings and chains. Carbon likes to form four bonds, which allows it to interact with a variety of molecules. The 4 bonds are essential for the formation of stable molecules. Carbon can bond in many different ways with many different elements.

How is Organic Different from Inorganic Chemistry?

Organic chemistry is defined as chemistry of living things. Most compounds discussed in organic chemistry are made up of carbon molecules. Many people think that organic chemistry revolves around carbon. However, that is not the case; there are some carbon molecules that are inorganic, such as carbon dioxide (CO2). Organic chemistry not only focuses on carbon but also on how electrons move in carbon compounds. The most simple answer for how organic is different from inorganic is that organic molecules are from living organisms while inorganic comes from non-living resources.

Introduction to Organic Chemistry

Organic chemistry is the chemistry of carbon; we know that carbon can also bond with many different elements forming various compounds.

Click here

Before learning organic chemistry, a review of the following topics may be useful:

Molecular Representations

There are a number of ways that a molecule or atom can be drawn. Some are simpler than others, depending on the type of information that the image is trying to convey. These representations are especially important in organic chemistry when considering the connectivity of atoms, electron distribution, formal charge, or bond type.

Skeletal Structure (Kekulé Structure)

 

In this form of representation, atoms are placed on a plane and lines are drawn between atoms to represent bonding electrons. Lone pairs are not included in this representation.

 

 

Condensed Structure

 

A simplified version of the bond-line structure that omits the lines. When there are 2 or more of the same kinds of atoms attached to a central atom, a subscript is used to indicate how many of these atoms are attached.

 

Lewis Structure

 

In this structure, valence electrons are represented as dots. This structure shows us what atoms are bonded together, which electrons are involved in bonding, lone pairs, and any formal charges.

 

Perspective Formula

 

In this formula, bonds that are on the plane are drawn normally. Bonds that protrude out of the plane towards the viewer are drawn as black wedges. Bonds that go into the plane away from the viewer are drawn as dashed wedges.

 

 

Naming Hydrocarbons

The simplest organic compounds are hydrocarbons. Hydrocarbons are compounds that consist of hydrogen and carbon atoms.

When naming hydrocarbons, the prefixes vary depending on the number of carbons in a compound, the prefixes are:

See Nomenclature for Organic Chemistry for more information on how to properly name organic molecules.

A trick to remember the prefixes of Met-, Eth-, Prop-, and But- is: Monkeys Eat Pink (or Plenty) Bananas.

The simplest type of hydrocarbons are called alkanes which consist only of single bonded atoms with a molecular formula of CnH2n+2 where n is equal to the number of carbons. They are named using the prefixes above, and by adding the suffix, "-ane."

Alkanes:                                                                          

CH4 - Methane

C2H6 - Ethane

C3H8 - Propane

C4H10 - Butane

Other kinds of hydrocarbons include: alkenes and alkynes. Alkenes are carbon compounds with at least 1 double bond between 2 carbon atoms, with the molecular formula CnH2n. They are named by adding the suffix, "-ene" to the prefix based on the number of carbons.

Alkenes:

 

C2H4 - Ethene

C3H6 - Propene

C4H8 - Butene

Alkynes are carbon compounds with one triple bond between two carbon atoms and are expressed with the molecular formula, CnH2n-2. They are named by adding the suffix, "-yne" to the prefix based on the number of carbons.

 

C2H2 - Ethyne

C3H4 - Propyne                              

C4H6 - Butyne

 

Naming Alkyl Compounds

Alkanes are often present as alkyl substituents (alkyl groups) that attach to other groups in larger organic molecules. Their molecular formulas have one less hydrogen than a normal alkane. They are named by replacing the normal alkane ending "-ane" with "-yl." The letter "R" commonly refers to any alkyl functional group.

Alkyl Substituents:

CH3- methyl

CH3CH2- ethyl

CH3CH2CH2-propyl

CH3CH2CH2CH2- butyl

R- any alkyl group

Examples of compounds with alkyl groups:

CH3I: methyl iodide   CH3CH2OH: ethyl alcohol   

CH3CH2CH2NH2: propylamine   R-O-R: an ether

CH3NH2: methylamine   CH3CH2OCH3: ethyl methyl ether  

 CH3CH2CH2CH2Cl: butyl chloride   R-NH2: an amine

Note that when there are two or more alkyl groups present, as in an ether, they must be stated in alphabetical order.

Structures of Organic Compounds

Alcohols:

consists of a hydrocarbons chain that has a hydroxide in place of hydrogen (anywhere in the compound). The common formula for an alcohol is R-OH, where R is any hydrocarbon (residue group). Naming alcohols is not hard either; for example propanol which comes from the propane hydrocarbon therefore instead of having the –ane suffix you have –anol.  Other examples are ethanol, butanol, Alcohols have the ability of making acids solutions. A common reaction of alcohols is with carboxylic acids to make water and an ester.

Ethers:

consists of two hydrocarbons joined by a oxygen between the them. Naming theses two compounds is as easy as naming the two alkyl groups (in alphabetical order) and ether at the end. An example is ethyl ether propyl, the structural formula is CH3CH2OCH2CH2CH3. Another example is ethyl ethyl ether more commonly named as diethyl ether. The common formula for ethers is R-O-R, this means there are two alkyl groups (aka residue groups).

Carboxylic Acids:

consists of an alkyl group missing three hydrogen that were replaced by double bonded oxygen and a hydroxide group. The common formula for carboxylic acids is R-COOH. Naming carboxylic acids is not hard, starting with propane and replaces the suffix –ane with -anoic acid, this compound is propanoic acid and has the structural formula of CH3CH2COOH. Some characteristics of this compound are reacting with alcohols to form water and an ester. Carboxylic acids also have a similar property to that of alcohols; both alcohols and carboxylic acids form weak acidic solutions in water.

Ester:

are generally formed through the reaction of carboxylic acids and alcohols. Esters are the reason why certain foods have certain scents; this makes the useful with perfumes. The general formula for an ester is R-COOR; naming esters is a little harder than naming other compounds but basically the alcohol gets the alkyl name ending and the carboxylic acid gets the –anoate i.e. methanol reacting with butanoic acid to make water and methyl butanoate; structural formula being CH3COOCH2CH2CH2CH3.

Aldehydes:

have the general formula R-CHO. Naming these compounds should not be confused with alcohols; aldehydes have the –al suffix while alcohols have the –ol suffix. For example methanal (aka formaldehyde) is the simplest aldehyde.

Ketones:

have the general formula R-COR and contain the suffix –one. An example of a ketone is butanone also know as methyl ethyl ketone to distinguish where the oxygen is located. Other was of identifying the location of the oxygen is by naming each carbon numerically and adding the number of the carbon, where the oxygen is found, to the formula, such as 2-butanone.

Halocarbons:

are essentially hydrocarbons where hydrogens have been replaced by halogens. When the halogens are in the compound you change the name, fluorine to fluoro, chlorine to chloro, bromine to bromo, and iodine to iodo. An example of this compound is 2-choloropropane, CH3CHClCH3. Like ketones, you should denote where the halogen is located in the compound by numbering the carbons in the compound.

Amines: 

contain a nitrogenous base and have the structural formula R-NH2. These compounds have the ability of making weak basic solutions by attracting hydrogen to form A R-NH3+. Naming this compounds just requires the addition of the suffix –amine after the alkyl name i.e. methylamine, CH3NH2.

Cycloalkanes

Cycloalkanes are alkanes that have ring, or cyclic structures. They have the molecular formula CnH2n. Because the atoms are arranged in a ring shape, the bond angles are less than they would be in ideal sp3 carbon. This is referred to as ring strain. As a result of ring strain, the bond energies of cycloalkanes are much less than those of regular alkanes. In order to avoid ring strain, cycloalkanes in nature are often found in different conformations. One example is the chair conformation of cyclohexane.

Cyclohexane

Cyclohexane, C6H12, is a cycloalkane with 6 carbons.

 

Cyclohexane is rarely found in its ring structure though because of its ring strain. More often it is found in a chair conformation. The bond angles in the chair conformer are very close to the ideal bond angles of sp3 carbons. About 110.9o compared to 109.5o (25) which is why this conformation is more stable than the ring structure.

 

Benzene

Benzene is a very important organic compound that is commonly used in manufacturing and as an organic solvent in labs. Its molecular formula is C6H6. In your organic chemistry textbook, you may see it presented in a ring structure:

 

It may be confusing as to how these "lines" can be a molecular structure. This notation is a quick method for chemists to draw organic molecules because the molecules can be very complex. In every corner, there is a carbon, bonded to hydrogen because carbon likes to make 4 bonds.

This is what the above structures of benzene actually represent:

 

Isomers and Stereochemistry

The structures of organic molecules are very important in considering their properties. Most organic molecules display geometric properties such as isomerism. Isomers are compounds with identical molecular formulas, but with different structures. There are 2 kinds of isomers: constitutional isomers and stereoisomers. Constitutional isomers differ in the connectivity of their atoms. Stereoisomers are compounds that maintain the same connectivity, but differ in the way their atoms are spatially arranged. There are 2 kinds of stereoismers: cis-trans isomers and enantiomers. Cis-trans isomers have different orientations of their functional groups. In a cis isomer, the highest priority functional groups are located on the same side of the double bond. In a trans isomer, the highest priority functional groups are located on opposite sides of the double bond. Enantiomers are compounds that have nonsuperimposable mirror images of each. A molecule or object that has a nonsuperimposable mirror image is chiral.

Constitutional Isomers: CH3CH2OH and CH3OCH3

Cis-trans Isomers:

 

Enantiomers:

 

Chirality and Enantiomers

In organic chemistry, the concept of chirality is often applied in medicine or compounds because the D-Dopa and the L-Dopa have different functions, one of them does the desired function, while the other one does not. This is because many biological receptor proteins in the body are shaped so that only one enantiomer can bind to the substrate, while the other cannot fit.  An example is sugar in biological systems, sugar is preferred in the D-Dopa form because in biological system, amino acids is preferred in the L-Dopa. The mirror images of the molecules does not have the same function as the other, they are usually called chiral. The two chiral molecules are called enantiomers. Non-chiral molecules are molecules that have a plane of symmetry in them and they are called achiral.

 

 

 

 

 

 

 

References

McMurry, John. Organic Chemistry Fourth Edition. Pacific Grove, CA: Brooks/Cole Publishing Company, 1995.

Bruice, Paula Y. Essential Organic Chemistry. 2nd. Upper Saddle River, NJ: Prentice Hall, 2010.