Hydrocarbon Derivatives, Organic Reactions and Petrochemicals Chapter 10 Hydrocarbon Derivatives, Organic Reactions and Petrochemicals

Introduction Oil and gas tend to drive the world economy. When its price is high so is everything else. Eg. Food Petrochemicals - are chemicals produced from petroleum. This includes plastics, asphalt shingles, paints, dyes, cosmetics, antifreezes, lubricants, adhesives, carpets, pesticides, fertilizers, and pharmaceuticals.

In this section we will study the chemistry of organic compounds that contain special groups of atoms called functional groups. These functional groups may contain oxygen, nitrogen, sulfur or halogens atoms. This group of organic compounds is referred to as hydrocarbon derivatives since they contain at least one element other than carbon and hydrogen. Functional groups give each class of compound some special chemical and physical characteristics.

Common Organic Compounds Through addition and substitution reactions, elements such as oxygen, nitrogen, sulfur and phosphorus can be included in the structure of hydrocarbons. The additions or substitutions of these atoms to create new organic products, creates the functional groups. The addition of functional groups provides us the possibility to create many new compounds through chemical reactions.

Functional Groups in Chem 30: Halogen in an organic halide Hydroxyl in a alcohol Carboxyl in a carboxylic acid Ester in an ester Amino in an amine (not in the curriculum)

10.1 Petrochemicals in Alberta The petrochemical industry in Alberta is a secondary and tertiary industry that converts crude oil and natural gas to value-added chemicals.

Some primary petrochemicals have immediate uses, but most of them undergo further chemical reactions to chemical derivatives. Methanol has immediate uses as - fuel, washer fluid and gas line antifreeze. Ethene may be used for helping to ripen some varieties of fruits.

Ethene Only 5% of our fossil fuels go towards producing petrochemicals. However, the economic importance of these petrochemicals is very important. The raw materials are processed and reprocessed many times creating many jobs.

Activity Section 10.1 Questions #1 & 2

10.2 Organic Halides These compounds are created through addition and substitution reactions when the hydrogen atoms are replaced by fluorine, chlorine, bromine or iodine so that the halogen becomes covalently bonded to a carbon atom in the hydrocarbon chain. Most are synthetically prepared, very few are found in nature. Their most common use is as pesticides and anesthetics. Organic Halides are considered a hydrocarbon derivative, because of the presence of one other element other than carbon and hydrogen.

Naming Organic Halides To name these compounds, we name the halogens as a halo–, ie. fluoro, chloro, bromo or iodo. Then we add the name of the parent hydrocarbon chain. If a halogen appears twice, we simply use the prefixes shown below to indicate the number of times the item is present. Prefixes di tri tetra Number 2 3 4

Examples of Organic Halides chloromethane difluoromethane   H H I I H - C – Cl H - C - F H F

Examples of Organic Halides 2,3-dichloro-2,3-difluoro-1,1-diiodobutane H Cl Cl I I I I I H - C - C - C - C - I H F F H

Properties of Organic Halides Increased halogen substitution (ie. more halogen atoms on the molecule) causes greater dispersion forces between molecules and therefore the boiling point increases. Also, boiling point increases if substitutions are with halogens from lower in the group (ie. larger atoms). Halocarbons are only slightly polar and are therefore not soluble in water but they are in other non-polar solvents such as octane.

Ozone Depletion An environmental concern has been raised by this type of reaction, which ends up producing products known as chlorofluorocarbons (CFC’s). These molecules have been used widely in foam products, as aerosol propellants and refrigerator/air conditioning coolants. Their use has been banned in the last 10 years or so but they are still present in many older refrigerators and AC units. Proper disposal of these appliances is essential to prevent further release of CFC’s.

CFC’s react in the atmosphere to destroy ozone molecules. As a result of this destruction, deadly UV radiation passes through our atmosphere and causes skin cancer. CFC’s have also been identified as a greenhouse gas and are so contributing to global warming.

Answers to Activity bromobenzene chloroethane 3-chlorobut-1-ene 1,4-dichlorobenzene (p-dichlorobenzene)

Organic Halide Reactions Halocarbons are chemically reactive. They are involved in a number of different reactions such as addition, substitution and elimination. We will look at elimination reactions after looking at alcohols.

Addition Reactions These occur when a substance is added to double or triple bonds in alkenes or alkynes, since these bonds are reactive. Addition reactions add a new functional group to a compound.

Addition When water is added, this is called a hydration reaction. This can occur when an alkene and water are heated to 100oC in the presence of a trace amount of a catalyst, such as nickel metal. H OH Ni I I H - C = C – H + HOH(l)  H - C - C - H I I I I H H H H ethene + water ethanol

Test for Unsaturation The addition of bromine to the carbon-carbon double or triple bonds is often used as a test for unsaturated organic molecules. Bromine has a brownish-orange colour. The loss of this colour when bromine is added to an organic compound is a positive test for unsaturation. Although benzene has double bonds, it is stable and does not give a positive test for unsaturation with bromine.

Example-Reaction 1 Br Pt I H - C ≡ C - H + Br2(l)  H - C = C - H I ethyne + bromine 1,2 - dibromoethene The addition of halogens to alkynes results in alkenes or alkanes.

Example-Reaction 2 Br Br Br l Pt I I H - C = C - H + Br2(l)  H - C - C - H I I I Br Br Br 1,2-dibromoethene + bromine  1,1,2,2 -tetrabromoethane Since addition reactions are very fast, the alkene produced, can undergo a second addition reaction.

Substitution Reactions Under the right conditions alkanes will undergo chemical reactions with halogens, such as chlorine: UV light Eg: CH4 (g) + Cl2 (g)  CH3Cl (g) + HCl (g) chloromethane Note that in situations such as this, ultraviolet light (UV light) is included as a catalyst.

Substitution Reactions A chemical reaction in which an atom or a group of atoms replace another atom or group of atoms is called a substitution reaction. In these reactions, the product of the previous reaction is reacted with chlorine again. We continue this process to end up with products such as chlorinated solvents, paint removers and degreasing agent.

Substitution Reactions This involves the replacement of an atom or group of atoms by another atom or group of atoms. For example: a halogen substituting hydrogen on an alkane to give a halocarbon: H H Cl H I I UV I I H - C - C - H + Cl2(g)  H - C - C - H + HCl(g) I I I I H H H H ethane + chlorine chloroethane

Substitution Example 2: This reaction is so slow that it requires both light and a catalyst.

Substitution Example 3: Alcohols may be produced by the substitution of a halogen by hydroxide ions: water & heat CH3CH2Cl (l) + NaOH(s)  CH3CH2OH (l) + NaCl(aq) chloroethane ethanol

Activity Section 10.2 Questions 2-5 & 7.