HSC Chemistry: Module 7 Organic Chemistry PDF

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HSC Chemistry: Module 7 Organic Chemistry...

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Nomenclature Inquiry question: How do we systematically name organic chemical compounds?

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investigate the nomenclature of organic chemicals, up to C8, using IUPAC conventions, including simple methyl and ethyl branched chains, including: Alkanes Single carbon-carbon bonds only, meaning the suffix ends in -ane. A methyl/ethyl branch is placed before with the prefix -anyl for methyl and -enyl for ethyl.

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Alkenes At least one double carbon-carbon bond, meaning the suffix ends in -ene. Rules for methyl/ethyl are the same as above.

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Alkynes

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At least one triple carbon-carbon bond, meaning the suffix ends in -yne. Rules for methyl/ethyl are the same as above.

- alcohols Primary ● Carbon attached to the -OH functional group is attached to one other carbon atom. Compound is given suffix -ol. Rules for methyl/ethyl are the same as above. Secondary ● Carbon attached to the -OH functional group is attached to two other carbon atoms. Compound is given suffix -ol. Rules for methyl/ethyl are the same as above. Tertiary ● Carbon attached to the -OH functional group is attached to three other carbon atoms. Compound is given suffix -ol. Rules for methyl/ethyl are the same as above. -

aldehydes and ketones

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Aldehydes contain the carbonyl group =O at the end of the parent chain. Compound is given suffix -al, following an, en, yn depending on carbon bond types. Rules for methyl/ethyl are the same as above. Ketones contain the carbonyl group =O anywhere on the parent chain except for the ends. Compound is given suffix -one, following an, en, yn depending on carbon bond types. Rules for methyl/ethyl are the same as above.

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carboxylic acids Carboxylic acids contain a carbonyl and a hydroxyl which form a carboxyl group -COOH. Compound is given suffix -oic acid, following an, en, yn depending on carbon bond types. Rules for methyl/ethyl are the same as above.

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amines and amides

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Amines contain the amino functional group -NH2. A primary amine has one alkyl group attached to the carbon of the functional group, a secondary amine has two alkyl groups and a tertiary amine has three alkyl groups. Compound given suffix amine, following an, en, yn depending on carbon bond types. Rules for methyl/ethyl are the same as above. Can also be listed from the N chain. Amides form when an amine reacts with a carboxylic acid to produce the amide functional group, -CONH2. Compound given suffix amide, following an, en, yn depending on carbon bond types. Rules for methyl/ethyl are the same as above. Can also be listed from the N Chain.

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halogenated organic compounds Halogenated compounds contain one or more halogen atoms attached to a carbon atom. Fluorine shortens to -fluoro, Chlorine shortens to -chloro, bromine shortens to -bromo, Iodine shortens to -iodo. Halogen branches are listed in alphabetical order. Methyl/ethyl are otherwise listed as normal.

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explore and distinguish the different types of structural isomers, including saturated and unsaturated hydrocarbons, including: chain isomers Chain isomers are made up of two or more carbon or other compounds with the same molecular formula but different atomic arrangements, or branches.

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position isomers Positional isomers are constitutional isomers that have the same carbon skeleton and the same functional groups but different location of the functional groups on or in the carbon chain.

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functional group isomers Functional Group Isomers have the same molecular formula, but different functional groups e.g cyclohexane and 1-hexene

Hydrocarbons Inquiry question: How can hydrocarbons be classified based on their structure and reactivity?

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construct models, identify the functional group, and write structural and molecular formulae for homologous series of organic chemical compounds, up to C8: Alkanes

- Alkenes (C = C)

- Alkynes (C ≅ C)

Alkyl Side Groups When Naming: ● Identify and name any side groups ● Side groups are written alphabetically in the compound name, e.g. 1-ethyl-2-methyl... ● Number the main chain carbon atoms consecutively, such that the side groups have the lowest set of ordinates ● A dash is used to separate numbers and letters, a comma is used to separate numbers

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conduct an investigation to compare the properties of organic chemical compounds within a homologous series, and explain these differences in terms of bonding

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analyse the shape of molecules formed between carbon atoms when a single, double or triple bond is formed between them

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The nature of bonding around each carbon atom of an organic compound influences the geometrical shape of that part of the molecule (VSEPR). The molecular arrangement can influence how close these molecules are able to compact together.

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explain the properties within and between the homologous series of alkanes with reference to the intermolecular and intramolecular bonding present Physical Properties of Alkanes The only type of intermolecular force in alkanes are dispersion forces. So alkanes generally have low B.P and M.P. ●

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At room temperature- C1 to C4 are gases, C5 to C10 are liquid and C>10 are typically solid. Colourless. Insoluble in water and Dissolve nonpolar substances (The weak dispersion forces between water molecules and hydrocarbon molecules are not strong enough to overcome the strong attraction between water molecules) Poor conductors of electricity (No free mobile charge carriers, no free electrons) Less dense than water (Dispersion forces hold molecules together more loosely than H-bonds) The strength of the overall dispersion forces between molecules increases as the molecular weight increases. (More electrons lead to a greater amount of temporary dipole interactions). ○ Therefore, larger alkane = higher B.P and M.P - The shape of the hydrocarbon also influences B.P and M.P ○ Linear molecules pack closer together allowing for a greater effect with the dispersion forces between the molecules. ○ Bulkier molecules (molecules with side chains) do not always pack together neatly, so less overall dispersion forces form. ○ Melting point versus carbon chain length has more of a step-like curve due to chains with even numbers of carbon atoms packing slightly more efficiently in the solid state than chains with odd numbers. The more efficient packing requires more energy to melt the compound. Physical Properties of Alkenes and Alkynes - Similar to their corresponding alkanes (same number of carbon atoms). - The location of the double and triple bonds influences the molecule geometry and hence also influences the physical properties. ○ The location of the double or triple bond changes the molecule’s ability to compact together, changing the effectiveness of the dispersion forces between the molecules. ○ Symmetrical structures allow for closer compaction between the molecules, and greater effectiveness of the dispersion forces between the molecules, leading to higher B.P and M.P. ○ Bulky structures do the opposite. Cyclic Hydrocarbons (Cyclo...) A hydrocarbon that contains carbon atoms joined together in a ring is called a cyclic hydrocarbon. They may contain single, double, or triple bonds in the primary chain. - Non-polar and share similar properties to their corresponding open-chain hydrocarbons - Less flexible than corresponding open-chain hydrocarbon since the single bonded carbons cannot freely rotate - Side groups are named similarly to open-chain hydrocarbon - Aromatic hydrocarbons contain one or more benzene rings ○ The electrons in the benzene ring are delocalised in that they can move around the structure ○ The cyclic delocalisation makes it extremely stable and reactions involving benzene will often maintain the ring structure

describe the procedures required to safely handle and dispose of organic substances Companies and labs which work with organic compounds must use Material Safety Data Sheets (MSDS) ○ MSDS provide specific details on the hazards, harm minimisation, and safest storing and handling practices for the compound of interest ○ MSDS must be checked prior to handling Many organic compounds are volatile due to weak intermolecular forces and hence can often form vapours at room temperature ○ The vapours of organic compounds are often colourless and cannot be seen ○ Most have an odour but it is not safe to detect a compound this way ○ Exposure to vapours is minimised by handling all organic compounds in a fume cupboard OR in an isolated chemical containment system Toxicity - Acute/Short-Term Health Effects ○ Headaches ○ Dizziness ○ Slowed Reaction Time ○ Loss of Consciousness - Chronic/Long-Term Health Effects ○ Chronic Fatigue ○ Liver and Kidney Damage ○ Damage to central nervous system ○ Immune system disorders ● -

Flammability Most organic compounds are highly flammable, especially in vapour form. - Flashpoint - The lowest temperature at which a liquid will ignite ○ The lower the flashpoint, the easier it is to ignite ○ Any organic substance with a flashpoint below 23°C is considered highly flammable ■ Cyclohexane ■ Cyclohexene ■ Ethanol ■ Pentane - Conduct experiments with organic compounds in well-ventilated rooms where there are no naked flames. Disposal of Organic Compounds ● Organic compounds for disposal are collected and stored in specific labelled containers which are taken by the appropriate disposal companies ● Organic compounds cannot be disposed of in regular drain systems as they can re-enter the environment and have detrimental effects ○ E.g. They may end up in the ocean as an oil layer, which is disastrous for aquatic life and birds

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examine the environmental, economic and sociocultural implications of obtaining and using hydrocarbons from the Earth

The most significant reaction that hydrocarbons undergo is combustion ● The first fuel sources to be exploited were wood and peat ○ These were used for cooking, baking, smelting and warmth ○ Burning fuel also provided energy for making new materials ● During the Industrial Revolution, coal (a hydrocarbon fuel) began to replace wood as the main source of energy in Europe and North America ○ Oil and coal gas were later used ○ Then in the 1960s, natural gas (composed of primarily methane but also consists of ethane, propane, butane, and pentane) began to replace coal gas ○ These all had a higher energy density than wood ○ These hydrocarbons were called fossil fuels ● In the past 250 years, the use of hydrocarbons for fuel has increased by nearly 800 fold, the consequences of this include: Effects Environmental ●

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Global warming, acid rain, smog, ozone depletion Destruction of natural ecosystems Contamination of groundwater systems which feed rivers etc.

Economic ● ● ● ●

Loss of income in the area of spills Large cost of clean-up of spills Job creation Increased economic output Increases availability of products and services

● Greenhouse effect - the trapping of the sun's warmth in a planet's lower atmosphere which is caused by the atmospheric gases that trap infrared radiation ○ Combustion of hydrocarbons releases greenhouse gases into the atmosphere ○ Main greenhouse gases include: ■ Carbon dioxide, methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons and sulphur hexafluoride.

Fractional Distillation of Petroleum (Crude Oil) ● Petroleum is a complex mixture of hydrocarbons with a vast

Societal ●

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From air pollution: Headaches, dizziness and nausea. Long-term effects include heart disease, lung cancer, and respiratory diseases. Mental impact of losses

range of hydrocarbon chain lengths ● The mixture is separated into fractions and then further refined before it can be used ● The crude oil mixture is separated based on differences in B.P using a fractionating column 1.Petroleum mixture is heated to a high temperature of approximately 400°C, vaporising a large portion of the mixture 2. Temperature decreased in the tower with increasing height, allowing the heated vapours to cool. 3. At different stages, hydrocarbons condense out of the mixture, separating the mixture into fractions ● Short chain molecules condense toward the top of the column ○ Short chain molecules have weak intermolecular forces = low M.P and temperatures decreases as we increase in height ● Long chain molecules condense toward the bottom of the column ○ Long chain molecules have stronger intermolecular forces = high M.P and temperatures are higher towards the bottom of the column ● These fractions are the raw materials that become the building blocks of polymers, pharmaceuticals, industrial solvents, and sources of fuel and energy powering electricity, industry, vehicles etc.

Fraction

Use

Gas

Used in LPG for cooking and heating. Also used in some automobiles.

Ethers

Solvents in industrial reactions. USed to create p;atsics

Petrol

Car fuel, Jet fuel

Light Oils

Hetaing oils

Lubricating Oils

Motor oils and used in cooking (fats), lubricants

Products of Reactions Involving Hydrocarbons Inquiry question: What are the products of reactions of hydrocarbons and how do they react? ●

investigate, write equations and construct models to represent the reactions of saturated hydrocarbons when substituted with halogens

investigate, write equations and construct models to represent the reactions of unsaturated hydrocarbons when added to a range of chemicals, including but not limited to: - hydrogen (H2) Hydrogenation of Alkenes ● In the presence of a nickel catalyst and at a temperature of 150°C, ethene will undergo an addition reaction with H2 gas to produce saturated alkane ethane ○ This type of reaction is used in the food industry to convert unsaturated fats and oils to margarine ●

○ Removing the (C=C) bonds increase the melting points, allowing for the substance to be solid at standard temperature

- halogens (X2) Halogenation of Alkenes ● The addition of elemental halogens such as chlorine (Cl2) or Bromine (Br2) results in a dihalogenated alkane

- hydrogen halides (HX) Hydrohalogenation of Alkenes ● The addition of a hydrogen halide (HX), to an alkene results in a single mono-halogenated alkane ● Markovnikov’s rule is applied (the rich get richer: In the reaction between an alkene and HX, the H will attach to the carbon with fewer alkyl groups and the X will attach to the carbon with more alkyl group - The Rich (the carbon with more alkyl groups) Get Richer (by gaining the halogen) - If the number of alkyl side groups are equal, there are multiple equally-likely products possible

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The stability of the carbocation increases with the no. of alkyl side groups attached, so a tertiary carbocation is more stable than a primary one (might not need to know this)

water (H2O) Hydration of Alkanes ● Ethanol can be produced by reacting steam with ethene in the presence of a catalyst, phosphoric acid, at 300°C and a pressure of 6-7 MPa ● Dilute sulphuric acid can also be used

Alcohols Inquiry question: How can alcohols be produced and what are their properties?

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investigate the structural formulae, properties and functional group including: Primary Secondary tertiary alcohols The position of the hydroxyl group classifies the alcohol as primary, secondary or tertiary If the hydroxyl (-OH) group is bonded to a carbon that is bonded to 1 other carbon it is a primary alcohol ○ If the carbon is bonded to 2 other carbons, it is a secondary alcohol

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○ If the carbon is bonded to 3 other carbons, it is a tertiary alcohol When naming alcohols, and numbering the chain, the location of the hydroxyl group takes priority over alkyl groups and halogens, but not double or triple bonds Alkanol - hydroxyl group is bonded to an alkane

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explain the properties within and between the homologous series of alcohols with reference to the intermolecular and intramolecular bonding present

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The most important physical property of alcohols is the polarity of their hydroxyl groups (C-O) and (O-H) bonds are polar Alcohols can have non-polar and polar parts of the molecule, the (-OH) group allows the formation of H-Bonds ○ Because of this, compounds such as ethanol can interact with both non-polar and polar molecules As molar mass increases, the physical properties of alcohols become more like those of hydrocarbons of similar molar mass ○ This is because, as molar mass increases, the non-polar part of the alcohol begins to dominate the nature of the molecule and the effect of the hydroxyl group is lessened Alcohols have higher B.P than alkanes of similar molar mass ○ H-Bonds, more energy required to overcome these strong intermolecular forces between alcohol molecules ○ Additional (-OH) groups further increase the extent of H-Bonds, leading to an even higher B.P ● The extent to which the (-OH) group will participate in H-Bonds depends on how exposed the (-OH) group is ○ Primary (-OH) groups are more free to participate in H-Bonds with surrounding molecules as they don’t have local methyl groups ○ Secondary (-OH) groups are less exposed than primary (-OH) groups ○ Tertiary (-OH) groups are the least exposed and their abilities to participate in H-Bonds is hindered the most ○ Therefore, the more exposed the (-OH) groups, the higher the B.P

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conduct a practical investigation to measure and reliably compare the enthalpy of combustion for a range of alcohols The heat of combustion of a fuel can be measured using a spirit burner calorimeter

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write equations, state conditions and predict products to represent the reactions of alcohols, including but not limited to: Combustion

- Dehydration Elimination ● Water is removed from alcohol via elimination in a process called dehydration ○ In elimination reactions, two substituents of the molecule are removed ○ In this case it is the H atom and the OH group removed to form water ● Dehydration is carried out by heating it with concentrated acid, usually sulphuric acid ● ●

An alkene and H2O are formed as products Tertiary alcohols dehydrate most readily, followed by secondary and then primary ○ Tertiary alcohols are the most reactive ○ Tertiary alcohols require the least heating to dehydrate, some can only need room temperature

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substitution with HX An alcohol is converted to halogenated compound via a substitution reaction The hydroxyl group at a saturated carbon is substituted for a halogen R - OH + HX -----> R - X + H2O

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Tertiary alcohols are the most reactive, followed by secondary, then primary

2-methylpropan-2-ol / tert-butanol to 2-bromo-2-methylpropane and water

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Hydrogen halide reactivity ○ The lower the bond enthalpy (average energy required to break a chemical bond) the more reactive the hydrogen halide ○ Hydrogen halide reactivity increases as you go down the halogen group on the periodic table ■ So from least to most reactive, (H-F) - (H-Cl) - (H-Br) - (H-I)

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oxidation In organic chemistry, electrons are transferred in the form of hydride ions (H-)

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OILRIG ○ Oxidation Is Loss (of hydrogen) ○ Reduction is Gain (of hydrogen) Reduction ○ When a carbon atom gains a bond to a hydrogen atom and loses a bond to an atom greater than or equal to the electronegativity of carbon ○ Adding hydrogen atoms to a carbon increases the electron density around carbon at...