Chemistry Notes: Naming Alkanes, Halides, Ethers, Alcohols, Conformations & Rotations - Pr, Assignments of Organic Chemistry

Download Chemistry Notes: Naming Alkanes, Halides, Ethers, Alcohols, Conformations & Rotations - Pr and more Assignments Organic Chemistry in PDF only on Docsity! Comments about Chap 2…2/1/08 About structure, nomenclature, conformations, cycloalkanes. Important topics: 1. Names of C1-C10 alkanes. Alkyl group common and IUPAC names. Know iso, tert-, sec-. What are structures, for example, of pentane, isopentane and neopentane? What are isobutyl, t-buty and s-butyl? 2. IUPAC system. 2-Chloropentane…can this be called sec-pentyl chloride? 3. Cycloalkanes…number so substituents have lowest possible numbers. 4. Alkyl halides…X’s are treated the same as alkyl groups for nomenclature purposes 5. Ethers…name the two substituents, end with “ether” 6. Alcohols…OH is attached to lowest numbered C. Eg, 3-methyl-2-butanol. “ol” is at the end of name because it id’s a functional group. 7. Amines…most complicated. Possibly can name substituents and end with amine. Eg, ethylmethylamine. If IUPAC is needed, id longest chain linked to N and use this as parent. Eg, CH3-NH-CH2-CH2-CH3 would be N-methyl-1-propanamine or N-methylpropan-1-amine. What is another name for ethylisopropylamine? 8. Properties (2.9)…self-study (slides # 16-18). We won’t cover this in class. HW problems assigned to this section provide an excellent guide as to what you should know. 9. C-C bond rotation (2.10) and conformations…different conformations of a molecule are related by rotations about a C-C bond. Newman projections. Staggered and eclipsed. a. ethane…12 kJ/mol (3 x 4 kJ/mol)…no need to remember corresponding kcal/mol values b. propane…eclipsed 14 kJ/mol (4 + 4 + 6) > staggered c. butane C2-C3 conformations…anti is most stable conformation (rel E = 0 kJ/mol). Gauche is 3.8 kJ/mol higher. Highest is 4 + 4 + 11 = 19 kJ/mol. Draw Newman projection for the conformation with relative E of 16 kJ/mol. 10. Cyclopropane…lots of angle and H eclipsing strain. Highest E/CH2. 11. Cyclobutane…butterfly shape provide some relief of angle strain 12. Cyclopentane…envelope shape 13. Cyclohexane…chair conformation. Effectively 0 angle strain and NO eclipsing. Two unique postions, axial and equatorial, are in equilibrium by ring flipping. Lowest E position for a substituent is equatorial. Other conformations are boat (no angle strain, yes eclipsing, serious flagpole H..H interactions), twist boat, half-chair. 14. Relative stabilities of cis-1,2-diXcyclohexane conformations, trans-1,2-…, cis and trans- 1,3- and 1,4- analogs.