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Ch 12 Alcohols, Ether, Thiols 1. Naming Functional Groups containing Oxygen Functional Groups • -OH hydroxyl group • -O- ether “ • C=O carbonyl “ carboxyl “ Molecule Class Alcohols Ethers Aldehydes, Ketones Carboxylic Acid Molecules and Functional Groups containing oxygen • have a bent shape • are polar, soluble in water • form H-bonds I. Alcohols • industrial ethanol production Alcohol Naming -OH 5 4 3 2 H3C -CH2- CH2 –CH- CH2-CH3 1 CH2-OH 1. Find longest C-chain containing -OH group. 2. Name: drop the alkane ‘e’ replace with ‘-ol’ pentanol 3. Number: –OH is attached to lowest C number Name: location-alkan-ol: 1-pentanol 4. Locate/list other substituents in front 2-ethyl-1-pentanol Multiple Hydroxyls • Include Carbon number • add –di, -tri, -tetra….ol • 1,2-propandiol 1,1-propandiol Warm-up A.) B.) A.) 3-methyl-2-pentanol B.) 4-methyl-2,3-pentandiol OH Hydroxyls on alkenes/ynes • OH group location overides double/triple bond numbering • Use the functional group name: Hydroxyl • List alpha • 2-Hydroxyl-4,4-dimethyl-trans-3-pentene Phenol • Benzene + Alcohol Group, must be called Phenol • Hydroxyl is always on C#1 Practice 2-methylphenol Classification of Alcohols: Primary, secondary, tertiary -OH attached to carbon with one other carbon and two H -OH attached to carbon with two other carbon and one H -OH attached to carbon with three other carbon and no H Practice • Draw the following alcohols in Kekule 1. 1-Hexanol 2. 3-Hexanol 3. 1,2,3-Hexantriol • Name and classify as 1st, 2nd, 3rd alcohol A B Sulfur Instead of Oxygen • Same number of valence e• Same number of bonds as oxygen • -SH is called a Sulfhydryl/Thiol group Polarities • EN of O: 3.5, S: 2.5, H: 2.1 Evaluate the polarities of the following bonds 1. O-H 2. C-O 3. C-S 4. S-H 5. C-H C-S produces a ____ polar bond than C-O Thiols -SH • Longest carbon chain including thiol: lowest number • Name: location-alkanethiol 1-propanethiol • multiple: locations- alkanedithiol, -trithiol 1-propanethiol 2-methyl-1-propanethiol 2- propanethiol -SH on complex Hydrocarbons • List alpha as thiol, the highest oxidized group determines numbering (O beats S) SH 2-hydroxyl- 3-methyl- 4-thiol-trans-2-pentene Ethers -O• Carbon chains on either side of ether are named alkyls according to length followed by etherlocation not necessary!!! • List alphabetically or use di- if identical • diethyl ether ethyl phenyl ether ethyl methyl ether 2. Alcohols, Ethers and Thiols in Nature Alcohols in Nature • Methanol: smallest alcohol in nature, toxic • Ethanol: byproduct of alcoholic fermentation (degradation of sugar in the absence of oxygen) C6H12O6 → 2C2H5OH + 2CO2 Glucose Ethanol CO2 causes fizzing, leavening bread… • Isopropanol: alcohol for disinfection, rubbing alcohol • Many flavors and aromas are alcohols: vanilla, thymol (thyme) eugenol (cloves), menthol Thiols in Nature • Strong, borderline smells in nature are usually Thiols: onion, garlic, aged cheese: break down of amino acid Methionine Ethers in Nature • First anesthesia was done with diethyl ether • Inhalation anesthesia • Very volatile, and explosive • Many side effects • Not in use anymore history of ether anesthesia 3. Polarity of Alcohols, Thiols and Ethers The Role of Oxygen • Oxygen has the second highest electronegativity of the PT: 3.5 Complete the table below: (EN: H: 2.1 and C: 2.5) bond C-H ∆EN Polar/ nonpolar? O-H C-O Polar Bonds = Polar Molecules! • In order to be a polar molecule it needs to have both: a. Polar bonds and b. Polar symmetry Polar Symmetries: Net Dipole Dipole Bent Pyrimidal δδ+ δδ+ Characteristics of Alcohols, Thiols and Ethers • Oxygen containing functional groups makes molecules polar! (Sulfur is not very electronegative (2.5) so does not make hydrocarbons very polar – only structural asymetry) • Hydroxyl will change the Melting, Boiling Point and Solubility Example: • Methane: gas • Methanol: liquid 4. Characteristics of Alcohols, Thiols and Ethers Melting/Boiling Point, Solubility in Water Characteristics of Hydrocarbons • • • • Non-polar Have low Melting/Boiling points Do not dissolve in water Only attractive forces are Van-de-Waals Characteristics of Alcohols (to some degree Thiols and Ether) • • • • Are polar Have a higher Melting/Boiling Point Dissolve in water Attractive forces include: H-bonds, Dipole Interactions and Van-de-Waals 3 Intermolecular Attractions: how they influence MP/BP and solubility in water 1. Hydrogen bonds – strongest intermolecular attraction • Intermolecular attraction of adjacent polar points (δ+, δ-) involving a Hydrogen • Indicated by a dotted line 2. Dipole Interactions • attraction of adjacent polar points δ+, δ- not involving H 3. Van-De-Waals attractions caused by very weak EN differences (0.4 and lower) Solubility in Water -A • Requires Hydrogen Bonds group polar HC chain length vs # of OH-groups Long HC chains reduce polarity/solubility in water alkane chain: non-polar alcohol group: polar not soluble so soluble forms H-bonds Solubility of alcohols vs HC Dissolving Molecules in H2O 1. Draw the molecule in VSEPR 2. Draw in all partial charges (δ+, δ+) 3. Associate 1 (one) H2O molecule per each δ+/- in the correct orientation (+ attracts -) 4. Draw in dotted lines 5. Example: Methanol Type and number of intermolecular attractions between molecules determines MP/BP Hydrocarbon VdW Dipole H-Bond + - Ether Alcohols + + - + + + Comparison of Alkanes, Ethers and Alcohols Compound Molar mass g/mole BP Soluble in H2O Butane 58 g/mol 0 Celcius no Ethyl methyl ether 60 g/mol 8 Celcius yes Propanol 60 g/mol 97 Celcius yes Melting and Boiling Points Fermentation Fermentation Warm-up 10 minute summary How and why does alcohol affect the body and how does the body deal with it. You may want to address the following…. a) which organs/tissues are affected by alcohol? b) which organs/tissues are responsible for break down? c) What are the long term affects of chronic alcohol abuse?