Alcohols and Phenols - Survey of Chemistry Lab II | CHEM 1152L, Lab Reports of Chemistry

Download Alcohols and Phenols - Survey of Chemistry Lab II | CHEM 1152L and more Lab Reports Chemistry in PDF only on Docsity! O H R H O H . . . Hydrogen bonding CH2 OHCH3 CH OHCH3 C OHCH3 CH3 CH3 CH3 ethanol (primary) 2-propanol (secondary) 2-methyl-2-propanol (tertiary) ALCOHOLS & PHENOLS An important portion of this course is the recognition of organic chemistry functional groups. These are parts of a molecule, with a specific structure that functions in a certain way. Not only are you to learn to recognize the functional groups (a listing can be found in your textbook or on the back cover of this laboratory manual), but you are also to learn the physical and chemical properties of each of the functional groups studied in the course. This laboratory exercise will introduce you to two of these functional groups, alcohols and phenols, as well as some of their physical and chemical properties. Alcohols Although you may be familiar with "alcohol” as a beverage, the word actually represents an entire classification of organic molecules and not just one substance. Alcohols contain the OH (hydroxyl) functional group attached to a saturated carbon. Notice that we did not call this the hydroxide ion, because this group does not act as an ionic substance. Alcohols are classified into three categories: primary (1°), secondary (2°) and tertiary (3°). This classification is based on the number of carbon-containing groups (R for an alkyl or an aromatic group) attached to the carbon bearing the hydroxyl group. If the carbon bearing the OH has one R group, the molecule is a primary alcohol. If two R groups are attached, it is a secondary alcohol. If three R groups are attached, the alcohol is tertiary. I. Physical Properties of Alcohols The hydroxyl group present in all alcohols is a polar functional group. The polarity of this group allows alcohols to form hydrogen bonds. Small chain alcohols are able to mix with water because of the hydrogen bonding interactions that will occur between the hydroxyl functional group and the water. If the R-group of the alcohol becomes too large however, the solubility of the alcohol will decrease. ZnCl2 Procedure: 1. Place 10 drops of each alcohol (ethanol, 1-butanol, 2-butanol, 2-methyl-2-propanol and 1-octanol) into its own test tube. Add 1-2 ml of water to each tube. Record your observations on the data sheet. 2. Place another 10 drops of each of the above alcohols into its own test tube. Add 1-2 ml of dichloromethane. Record your observations on the data sheet. !!CAUTION!! DICHLOROMETHANE IS FLAMMABLE. KEEP ALL FLAMES AWAY. AVOID BREATHING FUMES. WORK IN THE HOOD AS MUCH AS POSSIBLE. WEAR SAFETY GLASSES IN THE LABORATORY AT ALL TIMES! II. Chemical Properties of Alcohols The classification of an alcohol as primary, secondary or tertiary (see above) affects the chemical properties of the alcohols. This difference in chemical properties can be used as a means of identification. The Lucas test and the chromic acid test are two common methods used to distinguish among primary, secondary and tertiary alcohols. A. Lucas Test: The Lucas reagent contains zinc chloride and hydrochloric acid. When the Lucas reagent is allowed to react with an alcohol, an alkyl halide is formed. This alkyl halide will not be soluble in water, thus cloudiness or a second layer of droplets will form if the test is positive. With this reagent, tertiary alcohols react immediately, secondary alcohols in 3 to 10 minutes, and primary alcohols may take an hour or longer, or may never react. R-OH + HCl R-Cl + H2O (insoluble) Procedure: 3. Place 2 mL of the Lucas reagent in a test tube. Add 4 drops of ethanol. Shake the tube to mix the materials and note the time required for the mixture to become cloudy or to separate into two layers. Record your observations. Repeat this procedure for 1- butanol, 2-butanol, and 2-methyl-2-propanol. Note: In the interest of time, this phenol experiment can be carried out at the same time as the alcohol experiments. Consult instructor if there is a problem. !!CAUTION!! Chromic acid is very corrosive. Any spill should be immediately flushed with water. Wear safety glasses in the laboratory at all times. B. Ferric Chloride test Addition of aqueous ferric chloride to a phenol creates a colored solution. Depending upon the structure of the phenol, the color can vary from green to purple. Procedure: 7. Place 20 drops of the ferric chloride solution into a test tube. Add 5 drops of phenol solution. Note and record any observations on the data sheet. It is clear that some of the procedures will require some time to observe the results. The well- prepared student, who has read the laboratory exercise in advance, may realize that the phenol tests can be carried out at the same time some of the other tests are being done. These items need not be tested sequentially. Ask the instructor if you need help. UNKNOWN Obtain an unknown sample which is one of the following: 1-butanol, 2-butanol, 2-methyl-2- propanol or aqueous phenol. Using the information and knowledge gained during this laboratory, and by utilizing your critical thinking skills, determine the identity of this unknown. You can assume that if a test was not performed on a substance, the substance did not react with the reagent. Your report must include completion of the second data sheet which outlines the procedure for determining the unknown. You should make a hypothesis and then design or select an experiment which will support or invalidate your hypothesis. To verify the conclusion of your unknown, you must have at least three experiments designed to check and/or verify your hypotheses. Please be brief but clear and complete with your hypotheses, planned investigations, and conclusion. For the conclusion, use complete sentences, proper grammar, etc. DATA SHEET I Date Name Alcohols & Phenols Partners Solubility: Experiment ethanol 1-butanol 2-butanol 2-methyl-2- propanol 1-octanol phenol Solubility in H2O  Comp letely Soluble  Partia lly Soluble  Insolu ble  Comp letely Soluble  Partia lly Soluble  Insolu ble  Comp letely Soluble  Partia lly Soluble  Insolu ble  Comp letely Soluble  Partia lly Soluble  Insolu ble  Comp letely Soluble  Partia lly Soluble  Insolu ble Solubility in CH2Cl2  Comp letely Soluble  Partia lly Soluble  Insolu ble  Comp letely Soluble  Partia lly Soluble  Insolu ble  Comp letely Soluble  Partia lly Soluble  Insolu ble  Comp letely Soluble  Partia lly Soluble  Insolu ble  Comp letely Soluble  Partia lly Soluble  Insolu ble  Comp letely Soluble  Partia lly Soluble  Insolu ble Chemical Properties: Experiment ethanol 1-butanol 2-butanol 2-methyl- 2-propanol phenol Lucas Test Chromic Acid Test Ferric Chloride Test