lect32-apr21

lect32-apr21 - Chemistry 101-501 Spring 2010 Instructor:...

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Unformatted text preview: Chemistry 101-501 Spring 2010 Instructor: Dr. David P. Barondeau Office: Interdisciplinary Life Science Building Room 1196A Phone: 458-0735 E-mail: barondeau@tamu.edu (please put CHEM 101 in subject line) Lecture: MWF 9:10-10:00 Room 100 Heldenfels Office Hours: M 10:15 - 11:30 (Room 104A Heldenfels) W 10:15 - 11:30 (Room 104A Heldenfels) or by appointment Course Website: Blackboard Vista (http://elearning.tamu.edu/) Instructor Assistant: Jessica Garber jgarber@mail.chem.tamu.edu (Tues 7-9 Held 100) Supplemental Instructional Leader: Kathy Webb kmwebb2010@neo.tamu.edu 1 (Sun 9-10; Wed 7-8; Thurs 6-7 all in HRBB 15) Chemistry 101 • • • Homework problem set 7 has been assigned (due April 25th) Exam 4 will be on Friday April 30th (as originally scheduled) If you are having difficulty with the homework – – – Email: jgarber@mail.chem.tamu.edu (IA Jessica Garber) Email me at barondeau@tamu.edu My office hours • • M, W 10:15 to 11:00 (HELD 104A) T R 5-6:00 in ILSB room 1196A – TA Help desk HELD 116 SI Leader Kathy Webb kmwebb2010@neo.tamu.edu Sun 9-10; Wed 7-8; Thurs 6-7 all in HRBB 15 Instructional Assistant Jessica Garber jgarber@mail.chem.tamu.edu • Review sessions – – – Tues 7-9 HELD 100 2 Quiz 10 • • Define stereoisomers: molecules that have the same sequence of bonded atoms, but differ in the three-dimensional orientation of their atoms in space Draw 5 structural isomers (including hydrogen atoms) for the alkane C6H14. 3 Quiz 10 • Name the following two compounds 4 Quiz 10 • Describe the hybridization of the carbon atoms and the bonding interactions for a C=C double bond. What bond would have to be broken to interconvert the two species in question 3? 5 Functional Groups 6 Alcohols • Characterized by –OH group • Name: add –ol to name of hydrocarbon Me thanol Butanol 7 Alcohols Methanol – Used a solvent – As a fuel for high-powered As racing cars racing – Found in low Found concentrations in new wine wine – Like ethanol, causes Like intoxication intoxication • More poisonous because More the human body converts it to formic acid (HCO2H) and to H) formaldehyde (CH2O) formaldehyde • These compounds attack These the cells of the retina in the eye eye 8 “Sterno” • Alcohols burn in air Alcohols • A mixture of ethanol + mixture calcium acetate = STERNO STERNO 9 Alcohols 10 Alcohols How many different alcohol are derivatives of How pentane? Draw structures and name the alcohols pentane? 11 Alcohol properties s • Methane (CH4) iis a gas (boiling point, -161 °C) with low solubility in water solubility • Methanol (CH3OH) is a liquid (boiling point 65 °C) that OH) is miscible with water in all proportions miscible • Why the difference in properties due to the addition of Why one oxygen? one • Can think of alcohols as being related to water (HOH) – Substitution of H atom with an organic group – CH3 for methanol – CH3CH2 for ethanol • The two parts of the alcohol contribute to its properties – For example, methanol (unlike water) will burn--a property For associated with hydrocarbons – The boiling point of methanol, however, is more like that of The water water 12 Alcohol properties • The boiling point of a substance relates to the forces of The boiling attraction between molecules (intermolecular forces) attraction – The stronger the attractive intermolecular forces the higher the The boiling point boiling – These forces are particularly strong in water as a result of the These polarity of the OH group in the molecule polarity – Methanol is also a polar molecule, which leads to its high Methanol boiling point boiling – Methane is nonpolar and has a low boiling point as a result of Methane weak intermolecular forces weak 13 Alcohol properties • The solubility of alcohols are determined by their The solubility polar and nonpolar portions Methanol dissolves in water in Butanol is NOT soluble in Butanol water water 14 Ethers Ethers • Ethers have the general formula Ethers R-O-R’ R-O-R’ Diethylether is the best-known Diethylether ether ether – Colorless and highly flammable Colorless liquid liquid – Autoignition temperature of 170 °C Autoignition (can be ignited by a hot surface without a flame or spark) without – Low boiling point (34.5 °C) – Commonly used a laboratory solvent – Was used as a general anesthetic in Was surgery 15 Glycols: alcohols with two OH groups 1, 2ethanediol ethanediol (ethylene glycol) glycol) 1, 2propanediol propanediol (propylene glycol) glycol) 16 Types of alcohols H Primary R C H R S condary e R C H R Tertiary R C R 17 O H C 3C 2O , ethanol HHH C3 H O H rubbing alcohol H3C C H O H O H Amines Alcohols are derivatives of H2O (R–OH) (R–OH) and amines are derivatives of NH3 (Ramines are (RNH2) Methylamine Methylamine Primary amine Dimethylamine Secondary amine Trimethylamine Tertiary amine 18 Amines: properties Amines generally have terrible odors! You know the odor if you have ever You smelled decaying fish smelled Two amines, putrescine (1,4butanediamine) and cadaverine add butanediamine) to the odor of urine, rotten meat, and bad breath bad Cadaverine (1,5-pentanediamine) 19 Amines: properties Amines, like NH3, are bases 2 C6H5NH2 (aq) + H2SO4(aq) 2 C6H5NH3 +(aq) + SO42 -(aq) Aniline Anilinium ion 20 Amines Many natural products and Many drugs (such as nicotine and cocaine) are bases Two nitrogen atoms in the nicotine molecule can be protonated (form normally found) found) The protons can be removed The by treatment with a base by The deprotonated form is The much more poisonous and addictive addictive 21 Compounds with a carbonyl group Aldehyde Carboxylic acid Ketone 22 Oxidation of alcohols H H C H H C H OH (l) + O xi di z i n g ag e nt H H C O C H (l) Eth ano l H A c e t al d e h y d e + O xi di z i n g ag e nt H O C OH (l) Ethanol is a PRIMARY Ethanol ALCOHOL. It is oxidized to ALCOHOL It an ALDEHYDE and then to an ACID an H C H Ac e ti c aci d 23 Oxidation of alcohols OH oxidizi ng agent O R—C —R' H Secondary alcohol R—C —R' Ketone (–R and –R are organi c groups. They may be t he ' same or diff erent . ) SECONDARY ALCOHOLS are oxidized to KETONES — and reaction stops there 24 Oxidation of alcohols • Primary alcohols – Oxidation to aldehyde • R-CH2-OH → R-CHO + 2H+ + 2e- – Oxidation to carboxylic acid • R-CHO + OH- → R-COOH + H+ + 2e- • Secondary alcohols – Oxidation to ketone • R2-CH-OH → R-CO-R + 2H+ + 2e- • Tertiary alcohols – No oxidation • Common oxidizing agents – KMnO4 – K2Cr2O7 Potassium permanganate Potassium dichromate 25 Aldehydes and ketones • Have pleasant odors and are often used in fragrances • Benzaldehyde is responsible for the odor of almonds and cherries • Cinnamaldehyde is found in the bark of the cinnamon tree • Naming – Aldehydes end with “-al” – Ketones end with “one” Cinnamaldehyde 26 Aldehydes and ketones 27 ...
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