LOGO Course lecturer : Jasmin Šutković 16th November 2015 Organic Chemistry – FALL 2015 Lecture 6: ORGANIC COMPOUNDS THAT CONTAIN OXYGEN, HALOGEN, OR SULFUR

CHAPTER OUTLINE International University of Sarajevo 14.1 Introduction 14.2 Structure and Properties of Alcohols 14.3 Nomenclature of Alcohols 14.4 Interesting Alcohols 14.5 Reactions of Alcohols 14.6 FOCUS ON HEALTH & MEDICINE: Ethanol, the Most Widely Abused Drug 14.7 Structure and Properties of Ethers 14.8 FOCUS ON HEALTH & MEDICINE: Ethers as Anesthetics 14.9 Alkyl Halides Organic Compounds That Contain Sulfur Book chapter 14

Introduction  CHAPTER 14 concentrates on four families of organic compounds that contain a carbon singly bonded to a heteroatom—alcohols (ROH), ethers (ROR), alkyl halides (RX, X = F, Cl, Br, or I), and thiols (RSH).  Alcohols are the most widely occurring  Ethers are the most common anesthetics in use today  Alkyl halides, widely used as industrial solvents and refrigerants  The –SH group of thiols plays an important role in protein chemistry.

Alcohols can be prepared from, and converted into, many other kinds of compounds.

Alcohols, ethers, alkyl halides, and thiols are four families of compounds that contain a carbon atom singly bonded to a heteroatom—oxygen, halogen, or sulfur

Alcohols contain a hydroxyl group (OH group) bonded to a tetrahedral carbon atom. Alcohols are classifi ed as primary (1°), secondary (2°), or tertiary (3°) based on the number of carbon atoms bonded to the carbon with the OH group Structure of Alcohols

Common features Because oxygen is much more electronegative than carbon or hydrogen, the CO and OH bonds are polar. Since an alcohol contains two polar bonds and a bent shape, it has a net dipole. Alcohols are also capable of intermolecular hydrogen bonding, since they possess a hydrogen atom bonded to an oxygen.

Nomenclature  In the IUPAC system, alcohols are identifi ed by the suffi x -ol

 The most general method for preparing alcohols, both in the laboratory and in living organisms, is by the reduction of a carbonyl compound. Reaction of Alcohols

Alcohols also undergo —dehydration and oxidation. DEHYDRATION When an alcohol is treated with a strong acid such as H2SO4, the elements of water are lost and an alkene is formed as product. Loss of H2O from a starting material is called dehydration.

 Perhaps the most valuable reaction of alcohols is their oxidation to give carbonyl compounds—the opposite of the reduction of carbonyl compounds to give alcohols.  Primary alcohols yield aldehydes or carboxylic acids,  Secondary alcohols yield ketones,  Tertiary alcohols don’t normally react with most oxidizing agents Oxidation

 Recall section 12.8

FOCUS ON THE HUMAN BODY OXIDATION AND BLOOD ALCOHOL SCREENING  The first devices used to measure blood alcohol content in individuals suspected of “driving under the influence,” made use  The original breath analyzer test measured alcohol concentration in expired air by the color change occurring when the bright-orange oxidizing agent potassium dichromate (K2Cr2O7) reduced to blue-green chromium(III).

ETHANOL, THE MOST WIDELY ABUSED DRUG  Throughout history, humans drank lcoholic beverages for their pleasant taste and the feeling of euphoria.  In the beginning alcohol is a stimulant, largely because small amounts decrease social inhibitions, the ethanol (CH3CH2OH) in an alcoholic beverage, actually depresses the central nervous system.  The chronic and excessive consumption of alcoholic beverages has become a major health and social crisis, making ethanol the most widely abused drug in the United States.  One estimate suggests that there are 40 times more alcoholics than heroin addicts.

Ethers  Ethers are organic compounds that have two alkyl groups bonded to an oxygen atom. These two alkyl groups can be the same, or they can be different. Ethers have higher melting points and boiling points than hydrocarbons of comparable size and shape. Ethers have lower melting points and boiling points than alcohols of comparable size and shape.

Naming

FOCUS ON HEALTH & MEDICINE ETHERS AS ANESTHETICS  Diethyl ether...  Common anesthetic today  The discovery that diethyl ether (CH3CH2OCH2CH3) is a general anesthetic revolutionized surgery in the nineteenth century.

Alkyl Halides  Alkyl halides are organic molecules containing a halogen atom X (X = F, Cl, Br, I) bonded to a tetrahedral carbon atom. Alkyl halides are classified as primary (1°), secondary (2°), or tertiary (3°) depending on the number of carbons bonded to the carbon with the halogen.

Properties  Alkyl halides contain a polar bond, but since they have all of their hydrogens bonded to carbon, they are incapable of intermolecular hydrogen bonding.  Alkyl halides with one halogen are polar molecules, because they contain a net dipole. As a result, they have higher melting points and boiling points than alkanes with the same number of carbons.

Naming  In the IUPAC system, an alkyl halide is named as an alkane with a halogen substituent—that is, as a halo alkane. To name a halogen substituent, change the -ine ending of the name of the halogen to the suffi x -o (e.g., chlorine → chloro).

FOCUS ON THE ENVIRONMENT ALKYL HALIDES AND THE OZONE LAYER  Chlorofluorocarbons (CFCs) are simple halogen- containing compounds having the general molecular structure CFxCl4 – x. CFCs are manufactured under the trade name Freons.  Two examples are CFCl3 (Freon 11) and CF2Cl2 (Freon 12).

 CFCs are inert and nontoxic, and they have been used as refrigerants, solvents, and aerosol propellants.  Because CFCs have low boiling points and are water insoluble, they readily escape into the upper atmosphere. There, CFCs are decomposed by sunlight. This process forms highly reactive intermediates that have been shown to destroy the ozone layer (See figure)

ORGANIC COMPOUNDS THAT CONTAIN SULFUR Thiols are organic compounds that contain a sulfhydryl group (SH group) bonded to a tetrahedral carbon.

Thiols Vs Alcohols

Importance  The chemistry of thiols and disulfides plays an important role in determining the properties and shape of some proteins, as we will learn in Chapter 21.  For example, α-keratin, the protein in hair, contains many disulfi de bonds. Straight hair can be made curly by cleaving the disulfi de bonds in α-keratin, then rearranging and re-forming them, as shown schematically in Figure 14.7.

Readings  Book chapter 14