Chem 219 Unit 4 Exam Questions With 100% Correct Answers

Chem 219 Unit 4 Exam Questions With 100% Correct Answers What are the four halogen elements? - answerF, Cl, Br, I organohalide compounds - answerOrganic molecules containing halogen atoms (F, Cl, Br, I) Examples of how organohalide compounds are used by humans - answer- have been found in marine life (algae, mollusks, sponges, etc.), bc they metabolize the high concentrations of inorganic chlorides and bromides that are found in the seas. - Industrially, organohalides find uses as solvents, insecticides, herbicides, cleaning fluids, fire retardants, and refrigerants, among others. - In medicinal use, many organohalides are used as inhaled anesthetics and disinfectants. - The compound known as Teflon is a polymer that finds many uses as a lubricant and in non- stick applications such as cookware. Teflon is a polymer containing carbon-fluorine bonds instead of carbon-hydrogen bonds, as are seen in a typical organic molecule. What is the primary reason halogen-containing compounds are important in organic chemistry? - answerTheir reactivity They can be used as starting materials in the synthesis of larger and more complex organic molecules because of the variety of reactions that can occur in an organohalide molecule. What are two of the most important reaction types typical of organohalides? - answerSubstitution reaction (nucleophilic substitution reaction) Elimination reaction Substitution reaction - answerReplacing the halogen atom in a molecule with another atom or functional group Elimination reaction - answerA reaction that removes the halogen and hydrogen atoms from the original substrate molecule creating an unsaturated compound. Alkyl halides - answerAliphatic hydrocarbons (alkenes, alkanes, alkynes) that possess one or more halogen atom substituents. Since halogen atoms have the same bonding pattern as hydrogen atoms (forming one single covalent bond), they often take the place of hydrogen atoms in organic molecules. Aryl halides - answerAromatic hydrocarbons (benzene rings) with one or more halogen atoms attached to the ring (a compound in which a halogen is bound to the carbon of a benzene ring) Vinyl halides - answerHalogen is bound to a carbon of a double bond. Aromatic hydrocarbons - answerBenzene rings Aliphatic hydrocarbons - answeralkanes, alkenes, alkynes Nomenclature of halogen atoms - answerThe naming of alkyl and aryl halides follows the IUPAC systematic methods for nomenclature. Halogen atoms are treated as substituents on the parent chain of the molecule. The "-ine" suffix of the element name is removed and replaced with "-oro or -omo" as a suffix, corresponding to the specific halogen. Thus, chorine become chloro-, fluorine becomes fluoro-, bromine becomes bromo-, and iodine becomes iodo-. These substituent names are incorporated alphabetically into the IUPAC name of the compound. Ex: 1-bromo-1-chloro-3-iodocyclopentane What is the additional method of classification for Alkyl halides? - answerAlkyl halides are characterized according to the degree of "steric bulk" or structural substitution surrounding any carbon atom that bears a halogen. - the alkyl halide is primary (1°) if only one carbon is directly attached to the carbon bearing the halogen. - If there are two carbons directly attached to the carbon bearing the halogen, then the halide is classified as secondary (2°) - if three carbons are directly attached to the carbon bearing the halogen, the halide is tertiary (3°). - If there are only hydrogen atoms directly attached to the carbon bearing the halogen (no other carbons) then the halide is referred to as a "methyl" halide. Recognizing the degree of structural substitution of an alkyl halide molecule is important in being able to predict how the molecule will react under varying conditions and as to what products will form Subclassification of alkyl halides: if only one carbon is directly attached to the carbon bearing the halogen - answerprimary (1°) Image where R = a carbon Subclassification of alkyl halides: If there are two carbons directly attached to the carbon bearing the halogen - answersecondary (2°) Subclassification of alkyl halides: if three carbons are directly attached to the carbon bearing the halogen - answertertiary (3°) Subclassification of alkyl halides: If there are only hydrogen atoms directly attached to the carbon bearing the halogen (no other carbons) - answer"methyl" halide What symbol is used in place for a generic halogen atom? What symbole is used in place for a carbon atom sometimes? - answerX for a halogen atom R for a carbon atom What quality of the alkyl halide molecules is responsible for nucleophilic substitution reactions? - answerThe polarized carbon-halogen bond What does the polarization carbon-halogen bond look like in an alkyl halide molecule? - answerBecause halogens are more electronegative than carbon atoms the carbon becomes electron-deficient and as a result, gets a slight positive charge (as well as a slight negative charge on the halogen correspondingly). This phenomenon is present in all alkyl halide molecules. What is the abbreviation for a nucleophilic substitution reaction? - answerSn (Substitution, Nucleophilic) functional group interconversion - answerOne type of functional group (alkyl halide) is converted to another by substitution. By using nucleophilic substitution, a vast array of different types of compounds can be created starting from a simple alkyl halide.