An Introduction to Organic Chemistry: The Saturated Hydrocarbons

ALCOHOLS, PHENOLS, ETHERS AND THIOLS Ibrahim EU Serafi ND, PhD.

[Audio] 1. AlcoholsStructureandPhysicalProperties 2. AlcoholsNomenclature 3. MedicallyImportantAlcohols 4. ClassificationofAlcohols 5. ReactionsInvolvingAlcohols 6. OxidationandReductioninLivingSystems 7. Phenols 8. Ethers 9. Thiols Human&MedicalPerspective 31October2025 IbrahimEl-Serafi 2.

[Audio] The characteristic functional group of the alcohols and phenols is the hydroxyl group (-OH) In an alcohol, a hydroxyl group (-OH) is attached to a carbon chain In a phenol, a hydroxyl group (-OH) is attached to a benzene ring 31 October 2025 Ibrahim El-Serafi 3.

[Audio] Ethers have two alkyl or aryl groups attached to the oxygen atom May be thought of as substituted alcohols The functional group is R-O-R Thiols are a family of compounds that contain the sulfhydryl group (-SH) Structure similar to that of alcohols 31 October 2025 Ibrahim El-Serafi 4.

[Audio] Many important biological molecules (carbohydrates, lipids, proteins) contain hydroxyl and/or thiol groups In biological systems, the hydroxyl group is often involved in a variety of reactions such as oxidation, reduction, hydration, and dehydration Such as in glycolysis The thiol group is found in the structure of some amino acids and is essential for keeping proteins in the proper three-dimensional shape required for their biological function 31 October 2025 Ibrahim El-Serafi 5.

[Audio] Organic compound that contains a hydroxyl group (-OH) attached to an alkyl group The hydroxyl groups of alcohols are very polar Oxygen and hydrogen have significantly different electronegativities Hydrogen bonds can form between alcohol molecules 31 October 2025 Ibrahim El-Serafi 6.

[Audio] As a result, alcohols boil at much higher temperatures than hydrocarbons of similar molecular weight Large amount of heat needed to break the hydrogen bonds that attract the alcohol molecules to one another The boiling point of Butane = -0.5 oC Propanol = 97.2 oC Both have almost the same molecular weight 31 October 2025 Ibrahim El-Serafi 7.

[Audio] Alcohols are able to form intermolecular hydrogen bonds with water molecules One to four carbon atoms are very soluble in water Five or six carbons are moderately soluble in water Alcohols of seven carbon atoms or more are nearly insoluble in water As the nonpolar (hydrophobic) portion of an alcohol (the carbon chain) becomes larger to the polar (hydrophilic) region (the hydroxyl group), the water solubility of an alcohol decreases 31 October 2025 Ibrahim El-Serafi 8.

[Audio] An increase in the number of hydroxyl groups along a carbon chain will increase the influence of the polar hydroxyl group Proteins and nucleic acids have polar hydroxyl groups Allows intramolecular hydrogen bonding Keeps these molecules in the shapes needed for biological function 31 October 2025 Ibrahim El-Serafi 9.

[Audio] 1. Determine the name of the parent compound, the longest continuous carbon chain containing the -OH group 2. Replace the -e ending of the alkane chain with the -ol ending of the alcohol Alkane becomes alkanol Ethane becomes ethanol Propane becomes propanol 3. Number the parent chain to give the carbon bearing the hydroxyl group the lowest possible number 31 October 2025 Ibrahim El-Serafi 10.

[Audio] 4. Name and number all substituents, and add them as prefixes to the "alkanol" name 5. Alcohols containing two hydroxyl groups are named –diols 6. Alcohols containing three hydroxyl groups are called –triols A number giving the position of each of the hydroxyl groups is needed in these cases 31 October 2025 Ibrahim El-Serafi 11.

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[Audio] The common names for alcohols are derived from the alkyl group corresponding to the parent compound The name of the alkyl group is followed by the word alcohol For some alcohols, historical names are used (ethylene, glycol, glycerol) 31 October 2025 Ibrahim El-Serafi 13.

[Audio] Methanol Methanol (methyl alcohol, CH3OH) is a colorless and odorless liquid Used as a solvent and as the starting material for the synthesis of methanal (formaldehyde) Often called wood alcohol because it can be made by heating wood in the absence of air Toxic and can cause blindness and death if ingested 31 October 2025 Ibrahim El-Serafi 14.

[Audio] Ethanol Ethanol (ethyl alcohol, CH3CH2OH) is a colorless and odorless liquid Widely used as a solvent and for the preparation of other organic chemicals Used in alcoholic beverages Chronic alcoholism mothers: fetal alcohol syndrome (FAS), babies with abnormalities including mental retardation, poor growth (before and after birth), facial malformations Mothers who only social drinking may have children with fetal alcohol effects, reduced birth weight, some learning disabilities, behavioral problems 31 October 2025 Ibrahim El-Serafi 15.

[Audio] 2-Propanol 2-Propanol (isopropyl alcohol), was commonly called rubbing alcohol Patients with high fevers were often given alcohol baths to reduce body temperature Rapid evaporation of the alcohol results in skin cooling (no longer commonly used) Used as a disinfectant, an astringent (skin-drying agent), an industrial solvent, a raw material in the synthesis of organic chemicals It is colorless, has a very slight odor, and is toxic when ingested 31 October 2025 Ibrahim El-Serafi 16.

[Audio] 1,2-Ethanediol 1,2-Ethanediol (ethylene glycol), is used as automobile antifreeze When added to water in the radiator, it lowers the freezing point and raises the boiling point of the water It has a sweet taste but is extremely poisonous (color additives are used to ensure that it is properly identified) 1,2,3-Propanetriol 1,2,3-Propanetriol (glycerol), is a viscous, sweet-tasting, nontoxic liquid It is very soluble in water and is used in cosmetics, pharmaceuticals, and lubricants Important lipid structure (triglyceride) 31 October 2025 17.

[Audio] The carbon bearing the hydroxyl (-OH) group is called carbinol carbon Primary (1o), secondary (2o), or tertiary (3o) Depending on the number of alkyl groups attached to the carbinol carbon If no alkyl groups are attached, the alcohol is methyl alcohol A single alkyl group, the alcohol is a primary alcohol Two alkyl groups bonded to the carbinol carbon, a secondary alcohol Three alkyl groups bonded to the carbinol carbon, a tertiary alcohol 31 October 2025 Ibrahim El-Serafi 18.

[Audio] Classify each alcohol as 1) primary, 2) secondary, or 3) tertiary: OH | A. ___CH3—CH—CH2—CH3 B. ___ CH3—CH2—CH2—OH C. ____HO—CH2—CH2—CH2—CH2—CH3 31 October 2025 Ibrahim El-Serafi 19.

[Audio] Preparation of Alcohols The most important reactions of alkenes are addition reactions Addition of a water molecule to the carbon-carbon double bond of an alkene produces an alcohol (hydration) Requires a trace of acid (H+) as a catalyst 31 October 2025 Ibrahim El-Serafi 20.

[Audio] Preparation of Alcohols Alcohols may also be prepared via the hydrogenation (reduction) of aldehydes and ketones Similar to the hydrogenation of alkenes 31 October 2025 Ibrahim El-Serafi 21.

[Audio] Dehydration of Alcohols Alcohols undergo dehydration when heated with concentrated sulfuric acid (H2SO4) or phosphoric acid (H3PO4) Dehydration is an example of an elimination reaction -OH and -H are "eliminated" from alcohol to produce an alkene and water Dehydration is a reverse process for alcohol preparation from alkenes by hydration 31 October 2025 Ibrahim El-Serafi 22.

[Audio] Dehydration of Alcohols In some cases, dehydration of alcohols produces a mixture of products The dehydration of 2-phosphoglycerate to phosphoenolpyruvate is a critical step in the metabolism of the glucose 31 October 2025 Ibrahim El-Serafi 23.