Chapter 13 - Alcohols,Phenols,Thiols and Ethers PDF

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Alcohols,Phenols,Thiols and Ethers...

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CHEM 133 CHAPTER 13 CHAPTER 13 ● Alcohols and Phenols ○ Alcohol and Phenols contain oxygen as a functional group ● Alcohols: Contain a hydroxyl group (-OH) bonded to a hydrocarbon chain ● Phenols: Contain a hydroxyl group (-OH) bonded to a benzene ring ● Thiols: Contain a sulfhydryl or thiol (-SH) bonded to a hydrocarbon chain ● Ethers: Contain an oxygen atom that is bonded to two carbon atoms by single bonds ○ Are used as anesthetics in medicine ● Naming Alcohols ○ Alcohols are simply named by replacing the -e in an alkane with -ol ○ If the hydroxyl group is attached to only one or two carbons, you do not have to identify the location of the -OH with a number ○ You can also name by common name, which is the name of the alkyl group followed by “alcohol” ○ If the -OH is attached to 3 or more carbons, you must identify the position of the -OH with a number ○ More than one -OH attached: ■ One: -ol ■ Two:-diol ■ Three: -Triol ● Naming Cyclic Alcohols ○ Name as “cycloalkanol” ○ The -OH is always position 1 in the ring ○ Only have to number the position of other substituent (-OH always have position 1) ● Naming Thiols ○ Ass -thiol to the end of the alkane ○ Give -SH group the lowest number possible

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○ Thiols are also present in cyclic compounds Naming Phenols ○ The -OH attached to the benzene ring is always at carbon 1 ○ Use numbers only to identify the position of other substituents ○ Remember ortho,meta,para could also be used ○ Name includes substituents and ends with -Phenol Benzenethiol ○ Named Benzenethiol or thiophenol ○ Name the same as phenols Naming Ethers ○ The oxygen of an ether can be attached to either alkyl or aromatic groups ○ Two ways of naming ethers: Common or IUPAC name ○ Common Name: Name the alkyl or aromatic groups attached to the oxygen followed by the word ether ○ Alphabetic order ○ IUPAC: The smaller alkane is combined with the oxygen to form an alkoxy group, followed by the name of the longer alkane ○ Number identifies position of alkoxy group Isomers: Alcohols and Ethers ○ Alcohols and Ethers can be structural isomers ○ Same molecular formula, different atom arrangement ■ Ex) Ethanol and methoxymethane (molecular formula: C2H6O) Properties of Alcohols ○ Alcohols are classified as primary,secondary or tertiary ○ Primary: Has 1 alkyl group attached to carbon bonded to -OH group (methanol is also primary) ○ Secondary: Two alkyl groups attached to carbon bonded to -OH group ○ Tertiary: Three alkyl groups attached to carbon bonded to -OH group ○ Alcohols are capable of forming hydrogen bonds with each other

○ Oxygen of alcohol has partial negative charge, while hydrogen has a partial positive charge ○ Oxygen of one alcohol will form a hydrogen bond with a hydrogen from another alcohol ○ Alcohols can also form hydrogen bonds with water ■ 1-3 Carbons: Soluble in water at all concentrations ■ 4 carbons: Slightly soluble in water ■ 5 ore more: Insoluble in water ● Properties of Ethers ○ Ethers cannot form hydrogen bonds with each other ○ Result: Alcohols have higher boiling points than ethers (more energy required to break H bonds) ○ Can form hydrogen bonds with water but not as well as alcohols ○ Ethers with up to four carbons are slightly soluble in water ● Properties of Phenols ○ The -OH on phenols gives it very similar properties to other alcohols ○ The -OH allows phenols to H-bond with each other, which gives phenols a high boiling point ○ The -OH allows phenols to H-bond with water, which makes them slightly soluble in water ○ Ionizes with water as a weak acid ○ Very corrosive and irritating to the skin ● Reactions of Alcohols ○ Alcohols can undergo a variety of reactions ○ Are flammable and undergo combustion reactions in the presence of oxygen ○ Alcohols can be dehydrated (loss of water) to form alkanes ○ Saytzeff’s Rules: Major product formed is the result of hydrogen being removed from the carbon bonded to the fewest hydrogen atoms ○ Does not apply to primary alcohols ○ In Primary alcohols, the Carbon with -OH group is attached to only one other carbon, so only one product is possible

● Formation of Ethers ○ Ethers are formed by the dehydration of two alcohols ○ Requires high temperature and a catalyst ○ H and OH are removed from adjacent alcohols ● What is Oxidation? ○ Involves the loss of electrons ○ May result in either a loss of hydrogen or addition of oxygen ■ Ex) Oxidation of an alkane to a carboxylic acid results in an increase in carbon-oxygen bonds ○ Increase in oxygen, decrease in hydrogen ○ Reduction: Gain of electrons. Decrease in oxygen, increase in hydrogen ○ Primary vs secondary alcohols give different end products ○ Primary can be oxidized to an aldehyde which is further oxidized to a carboxylic acid ○ Aldehydes are rapidly oxidized to carboxylic acids ○ Secondary alcohol can be oxidized to a ketone ○ No hydrogen left to remove from the carbon of the ketone group, so no further oxidation occurs ○ Tertiary to not oxidize because no hydrogen are attached to carbon bonded to OH...