Organic Chemistry Tutorial
An organic chemistry tutorial covers many topics and lessons in order to be comprehensive. Naming and recognizing common collections of atoms called functional groups is one of the relevant topics. Atomic electronegativity is crucial to predicting general molecule behavior. You will practice predicting reaction products and transformations. Intermediate molecules and parallel reactions are important in predicting mass/energy dynamics during and after organic processes.
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Instructions
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Memorize common organic functional groups and the related naming scheme. For instance "-OH" is the hydroxyl functional group common in many organic compounds. Propyl alcohol and potassium hydroxide both contain the "OH" functional group even though the two substances are named slightly different with respect to the "OH." "Alcohol" and "hydroxide" refer to the same oxygen-hydrogen group. This "multiple naming" phenomenon is common in organic chemistry.
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Organize atoms by electronegativity. This is done to predict likely reaction paths. Groups with low electronegativity are electron donors. Higher electronegativity values imply electron acceptors. Partial charges help to indicate electron donors and acceptors. Consider methanol, expressed as CH3---OH. The "OH" hydroxyl has a higher electronegativity due to the oxygen than methyl (CH3). Therefore, the carbon end of the molecule has a slight positive charge and the "OH" electron acceptor has a corresponding slight negative charge.
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Practice predicting organic reaction products. Electrons and atoms shuffle between---and within---organic molecules with surprising complexity. Steric and kinetic effects influence correct, or even likely, reaction steps.
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Capture information about intermediates and parallel reactions. Intermediates exist briefly before transforming into other intermediates and/or products. Parallel reactions may be obvious or subtle, producing only tiny traces of "parallel product." Intermediate molecules and parallel reactions are inferred by methods such as spectroscopy, mass and energy balance as well as reaction mechanism predictions.
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Tips & Warnings
In organic chemistry notation the symbol R refers to a generalized portion of a molecule that is not of interest. Different generalized portions are differentiated by hash marks---R and R'---for instance.
The same molecule can be written differently, depending on the functional group of interest. For example, CH3---CH2---(C=O)---CH2---OH can be written as CH3-R to focus on the methyl (CH3) functional group. Alternatively, the molecule can be expressed as R---(C=O)---R' to draw attention to the central carbon-oxygen bond and R-OH if the hydroxyl is of primary concern.
Carbon and oxygen are the dominant atoms in methanol; they determine overall charge distribution and electron behavior. Oxygen has electronegativity of 3.44, while electronegativity of carbon is 2.55. The bigger oxygen values means that oxygen is has a thicker electron cloud and partial negative charge.
"Steric" refers to molecule geometry and size. For example, H2 reacting within a tight space in a complicated organic molecule will behave slightly differently than H---Br. Aside from electronegativity differences, reaction predictions would take into account the fact that the bromine (Br) is much bigger and heavier than hydrogen (H) atoms.
Organic chemistry has a vast experimental component. Follow all relevant rules about safe handling and proper waste product disposal.
References
- Northern Arizona University: Functional Group Table
- Tutoring and Homework Help: Electronegativity Table of the Elements
- Towson University: Writing Mechanisms in Organic Chemistry
- Colby College: Parallel Reactions---Competitive Reactions
- University of Wisconsin, Madison: Symbolic Notation in Organic Chemistry
Resources
- Photo Credit vitamin c - ascorbic acid image by Cornelia Pithart from Fotolia.com
