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Organic Chemistry

Organic Chemistry

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Organic Chemistry

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  1. Organic Chemistry Organic Chemistry: Study of the compounds of Carbon 7 million examples Inorganic Chemistry: Study of molecules without Carbon ( 1.5 million examples)

  2. Hydrocarbons Organic molecules consisting only of carbon and hydrogen with covalent bonds. Major components of fossil fuels such as coal, oil or gas. They consists of partially decomposed remains of organisms that lived millions of years ago. Methane is a fossil fuel, it is easily made in anaerobic conditions with manure and bacteria (also in swamps or dumps)

  3. Hydrocarbons CH4 Methane

  4. Methane Production Methane can be produced in: • Coalmines • Slurry pits • Waste dumps • Digestive tracts of animals

  5. Hazards of Methane Production • Fires and explosions • Death by suffocation • Contributes to the greenhouse effect

  6. Empirical Formula = formula represents the lowest ratios of the element in a compound Molecular Formula = a molecular formula describes the numbers of different kinds of atoms in a molecule Structural Formula = a structural formula represents a two-dimensional model of how the atoms are bonded to each other. Each dash represents a bonding pair of electrons. Condensed Structural Formula = structural formula written not drawn

  7. **Ignore that it’s Spanish (I think)

  8. Draw a carbon atom How many monovalent atoms can bond to carbon? What shape and bond angle will carbon molecule have? 109.5 What type of bond? Covalent or ionic

  9. Definition • Saturated =  chemical compound that has a chain of carbon atoms linked together by single bonds and has atoms filling all of the other bonding orbitals of the carbon atoms. (SINGLE BONDS ONLY- BONDING ORBITALS FULL) • Unsaturated compound is a chemical compound that contains carbon-carbon double bonds or triple bonds, such as those found in alkenes or alkynes, respectively. (CONTAINS DOUBLE/ TRIPLE BOND)

  10. Tetrahedral compounds are saturated • Alkanes • Chloroalkanes [Haloalkanes] • Alcohols • Where-ever there is a double or triple bond they become planar

  11. Carbon skeletons can vary in length.

  12. Organic compounds An aromatic compound is a compound that contain a benzene ring. Aliphatic compound is an organic compound that consists of open chains of carbon atoms and closed chains compounds (ring) that resemble them in chemical properties eg. Cyclohexane

  13. Cycloalkanes are alkanes (only carbon to carbon single bonds) which form a ring cyclohexane • The "straight" chain has carbon atoms that are able to rotate freely around their single bonds, sometimes linking up in a closed ring. • Ring compounds of the first four cycloalkanes =

  14. Aromatic Hydrocarbons Delocalised electrons • Contain benzene rings Benzene: C6H6 • unreactive (less than expected), • alternating double and single bonds with bond length between single and double bond length • Stable • insoluble in water • Toxic • Carcinogenic • good organic solvent • planar

  15. Range and scope of aromatic chemistry • Methyl benzene is used as a industrial solvent • Pharmaceutical compounds, e.g. Morphine • Herbicides, e.g. Diuron • Detergents, e.g. Sodium dodecylbenzenesulfonate • Dyes, e.g. Martius Yellow • The acid-base indicators phenolphthalein and methyl orange are also aromatic compounds:Phenolphthalein, Methyl orange • Benzene is carcinogenic

  16. Homologous series • Alkanes occur in what is called a homologous series. • A series of compound of uniform chemical type • Showing gradations in physical properties • Having a general formula for its members • Each member having a similar method of preparation • Each successive compound differs from the one before it only by a CH2

  17. Homologous series

  18. Alkanes Ethane Butane • Only have single bonds between carbons (saturated) • Have maximum amount of Hydrogens • End with –ane • CnH2n+2 • Fairly unreactive but do burn in oxygen, used as fuel due to high heat of combustion, cheap and clean products • Tetrahedral shape (not planar) 109.5o angles • Non-polar so immiscible in water C1-C4 (gas) C5-C12 (liquids) C13-C31 (waxy solids) C32+ (solids).

  19. C1to C4 Gases C5 to C16 Liquids C17 + Waxy Solids

  20. Natural gas is pure methane Bottles gas is propane and butane

  21. General formulaCnH2n+2 Identify the number of H’s in each alkane C5Hx C10Hx C16Hx C55Hx C3Hx C28Hx C21Hx C4Hx C15Hx What state?

  22. Need to know how to draw structural formula • Must know how to draw from nameor vice versa • CH3CH2CH(CH3)CH3

  23. Branching • Skeletons may be branched or unbranched. Butane C4H10 2-methylpropane (commonly called isobutane)

  24. Structural Isomers • Are compounds with same molecular formula but different structural formulas • The number of isomers increases tremendously as carbon skeletons increase in size. • Only need to know to C5 2 Structural Isomers of Butane

  25. Naming alkanes (IUPAC) • Identify the longest continuous chain of carbons. = parent name/compound • The locations or other groups of atoms attached to the longest chain are identified and numbered by counting from the end of the molecule which keeps the numbering system as low as possible. • Hydrocarbon groups that are attached to the longest continuous chain and named using the parent name and changing the –ane suffix to –yl. • For groups attached, priority is given based on alphabetical order i.e. ethly before methyl

  26. Functional groups • Is an atom or group of atoms which is responsible for the characteristic properties of a series of organic compounds • Eg. methyl, ethyl, propyl • Eg. halogens • Electronegative functional groups increase the molecules reactivity with polar molecules and solubility in polar molecule eg. water

  27. Chloroalkanes • Physical state: Liquid, except for chloromethane and chloro-ethane, which are gases at room temperature • Boiling points higher than the corresponding alkanes(most liquids except C1 &C2), due to polar C-Cl bond(s) (but only weak) • Not soluble in water • Soluble in non-polar solvents such as cyclohexane • Because of their weak polarity, they are useful organic solvents, e.g. for • removing grease and oil from machinery • removing oil etc. from clothes - dry cleaning • Fully halogenated alkanes are flame retardant so used in fire extinguishers

  28. Naming chloroalkanes • Last part of name comes from base alkane on which the molecule is built, e.g. chloroethane[2 carbons] • Number of chlorine atoms indicated by prefix mono, di, tri, tetra etc. in front of chloromethane, e.g. trichloromethane • Position of each chlorine atom given by a number before the name, e.g. 1,2,2-trichloropropane

  29. Ethene Butene Alkenes Alkenes are different to alkanes; they contain DOUBLE COVALENT bonds. • CnH2n • Unsaturated • Ethene is the 1st member • C2 to C4 are gases, boiling pt increases with increasing carbon chain • More reactive than alkane • Undergoes addition rxns • Test for alkenes = 1. they turn bromine water colourless 2. acidified KMnO4 colourless. • planar

  30. Ethene is used to make polyethene By polymerisation rxn (addition rxn with H2 as a by product) • Ethene is the gas that ripens fruit, and a ripe fruit emits the gas, which will act on unripe fruit. Thus, a ripe tomato placed in a sealed bag with green tomatoes will help ripen them. • Ethene is used to make ethanol for industrial use

  31. Naming Alkenes • Naming is similar to naming alkanes except: • The longest continuous chain must contain the double bond. • The base name now ends in –ene. • The carbons are numbered so as to keep the number for the double bond as low as possible. • Number the double bond on parent (in word or before) i.e. pro-1-ene, 1 propene • The number which identifies the location of the double bond takes priority to functional groups

  32. Alkynes • An alkyne is a hydrocarbon with at least one carbon to carbon triple bond. • Naming an alkyne is similar to the alkenes, except the base name ends in –yne. • Even more reactive due to triple bond • Planar • Highly unsaturated • CnHn-2

  33. Alcohols In the alcohols it is the OH [hydroxyl] group General Formula CnH2n+1OH Members of this Homologous Seriesare • Methanol CH3OH • Ethanol C2H5OH • Propanol C3H7OH • Butanol C4H9OH etc.

  34. Classification

  35. Primary Alcohols H H H | | | H - C - C - C - OH | | | H H H Propan-1-ol The C to which the OH is attached has only got one C attached directly to it.

  36. Secondary Alcohols H H H | | | H - C - C - C - H | | | H OH H Propan-2-ol The C to which the OH is attached has got two C’s attached directly to it.

  37. Tertiary Alcohol [Not needed now] H | H - C - H H | H | | | H - C - C - C - H | | | H OH H 2, Methyl Propan-2-ol The C to which the OH is attached has got three C’s attached directly to it.

  38. Intermolecular Force between molecules dictate it’s B. Pt. and M. Pt

  39. Boiling Points of alcohols • Higher than expected for their RMMs • due to polar OH group • Polarity due to a difference in electronegativity between O and H • O = 3.5 : H = 2.1 difference 1.4 • leads to Hydrogen Bonding • Compare Methanol and Methane [RMM approx 30]

  40. Solubility is controlled by the molecules attraction to water • As a general rule ‘Like dissolves like’ i.e. polar substance will dissolve other polar substances. • The lines get a bit blurry when you have slightly polar substances as the can have slight solubility or poor solubility i.e. they dissolve little bit

  41. Solubility Methanol in • (i) cyclohexane – not soluble methanol is polar cyclohexane is not • (ii) water - completely soluble or miscible [infinitely soluble] because it is polar. • Like dissolves like • Polar dissolves polar • As alcohol gets bigger the polar part becomes less significant so it becomes less soluble in water and more soluble in cyclohexane