Presentation on theme: "Organic Chemistry = Chemistry of carbon compounds = chemistry of living things."— Presentation transcript:
Organic Chemistry = Chemistry of carbon compounds = chemistry of living things.
Bonding of Carbon Atoms Carbon atoms have a tendency to covalently bond with other carbon atoms and form chains. Carbon atoms are able to form up to four covalent bonds: **Remember: Carbon atoms can engage in single, double, or triple covalent bonds: saturated compounds = carbon atoms have 4 single bonds. unsaturated compounds = carbon atoms have one or more multiple bonds (double or triple).
This double bond between the two carbon atoms makes this organic compound unsaturated.
Molecular Formulas – indicates the actual number of atoms of each element in one molecule of a substance. Structural Formulas – shows not only the number and kinds of atoms in the molecule but also the arrangement (connections) of the atoms. Molecular FormulaStructural Formula Condensed Structural Formula CH 4 CH 4 C 2 H 6 CH 3 CH 3 Molecular vs. Structural Formulas
Hydrocarbons = Compounds composed of carbon and hydrogen only. Homologous series of hydrocarbons: (a) Alkanes = - General formula: (b) Alkenes = - General formula: (c) Alkynes = - General formula:
Naming Organic Compounds Naming straight-chained hydrocarbons: Use Organic Prefixes, and Homologous Series of Hydrocarbons) to name & write the formulas. When naming alkenes & alkynes, indicate where the double/triple bond is located in the molecule. **The carbons are numbered so as to keep the number for the double bond as low as possible** The double bond is located on the 1 st carbon…so its name would be: The double bond is located on the 2 nd carbon…so its name would be: Both compounds have four carbons (use prefix but-) and a double bond (use ending –ene) Both compounds have four carbons (use prefix but-) and a triple bond (use ending –yne) The triple bond is located on the 1 st carbon…so its name would be: The triple bond is located on the 2 nd carbon…so its name would be:
Naming Organic Compounds Naming branched hydrocarbons: 1) Find the longest carbon chain which contains the functional group or multiple bond if present and name it (find correct prefix & ending). 2) Number the longest chain (left to right or right to left) so that the functional group/multiple bond/longest side chain (branch) is on the lowest numbered carbon possible. 3) Name each side group but change the ending to -yl. 4) Use a prefix di-, tri-, tetra-, etc. to denote how many side groups of each length are present. 5) Before naming the side group give the number of the carbon to which the side group is attached. 6) Arrange the side groups in alphabetical order ignoring the prefixes di-,tri-, etc.
Examples: 1.) The longest chain has 5 carbons, so the prefix pent- must be used. 2.) There are only single bonds, so the ending –ane must be used. 4.) Since the side group is right in the middle, the carbons can be numbered from either side. The methyl group is located on the 3 rd carbon. 3.) The side group has only one carbon, so use the prefix meth- and add the ending –yl: methyl. Name: 1.) The longest chain has 4 carbons, so the prefix but- must be used. 2.) There are only single bonds, so the ending –ane must be used. 4.) Count carbons so that the longest side chain has the lowest #. The first 2 methyl groups are located on carbon 2, and the next methyl group is located on carbon 3. 3.) Each side group has only one carbon, so use the prefix meth- and add the ending –yl: methyl. Since there are 3 methyl groups, use the prefix tri-: trimethyl. Name:
Isomers = **As the # of carbon atoms in a compounds increases, the # of possible isomers also increases.** Three of these compounds have the molecular formula C 5 H 12. Which compound is not an isomer of the others?
Functional Groups = atoms or groups of atoms that can replace hydrogen atoms in a hydrocarbon and give the compound distinctive physical and chemical properties (1)Halides: = when any of the halogens (F, Cl, Br, or I) replaces a hydrogen atom in an alkane - named by citing the location of the halogen attached to the chain and adding the appropriate prefix (fluoro-, chloro-, bromo-, or iodo-) Note: Table R provides examples on how to recognize and name compounds w/ each of the functional groups!
(2) Alcohols: = one or more hydrogen atoms of a hydrocarbon are replaced by an –OH group (called a hydroxyl group) - named by citing the location of the –OH group and changing the ending to –ol. - Classifying alcohols: Note: The –OH group does not dissociate, and therefore alcohols are not bases/electrolytes. However, the –OH group does make alcohols polar molecules. Monohydroxy alcohol: one –OH group Dihydroxy alcohol: two –OH groups Trihydroxy alcohol: three –OH groups
- Alcohols can also be classified according to the position of their –OH group: PRIMARY (1 o ): the functional group is bonded to a carbon that is on the end of the chain. SECONDARY (2 o ): The functional group is bonded to a carbon in the middle of the chain. TERTIARY (3 o ): The functional group is bonded to a carbon that is itself directly bonded to three other carbons.
(3) Aldehydes: = the carbonyl group (-C=O) is found on the end carbon - named by substituting –al in place of the final –e of the corresponding alkane name
(4) Ketones: = the carbonyl group (-C=O) is found on an interior carbon atom that is attached to two other carbon atoms - named by replacing the final –e from the corresponding alkane with –one; if necessary, cite which carbon atom the carbonyl group is attached to.
(5) Ethers: = two carbon chains are joined together by an oxygen atom bonded between two carbon atoms - named by first naming the two methyl groups, followed by the word ether (when both R groups are the same, use prefix di-)
(6) Organic Acids: = contain the carboxyl functional group (-COOH) - named by replacing the –e in the corresponding alkane name with –oic acid
(7) Esters: = have the type formula R-CO-OR’ (R-CO-O- part of formula comes from an organic acid; the R’ part comes from an alcohol- see Esterification) - named for the alcohol and organic acid that make up the ester
(8) Amines: = formed when one or more of the hydrogen atoms of ammonia are replaced by an alkyl group - named by changing the alkane ending of –e to –amine and then numbering the alkane chain to show the location of the amine group
(9) Amides: = a compound formed by the combination of two amino acids (See Condensation reaction) - named by changing the carboxylic acid acid reactant ending –oic acid with -amide
Organic Reactions **Note: Generally occur more slowly than inorganic reactions. When covalently bonded substances react, they must first break relatively strong existing bonds before making new bonds.** (1)Combustion: = Hydrocarbons burn in the presence of oxygen to produce water and carbon dioxide
(2) Substitution: = involves the replacement of one or more of the hydrogen atoms in a saturated hydrocarbon with another atom or group (3) Addition: = involve adding one or more atoms at a double or triple bond Ethene
(4) Esterification: = the reaction between an organic acid and an alcohol to produce an ester plus water (5) Saponification: = when an ester reacts with an inorganic base to produce an alcohol and a soap Organic Acid + Alcohol Ester + Water
(6) Fermentation: = a chemical process in which yeast cells secrete the enzyme zymase and break down sugar into carbon dioxide and two carbon fragments of alcohol (7) Polymerization: = the formation of large polymer molecules (a) Addition polymerization = involves the joining of monomers of unsaturated compounds (b) Condensation polymerization = involves the joining of monomers by removing water from hydroxyl groups and joining the monomers by an ether or ester linkage Polymers = organic compounds make up of chains of smaller units covalently bonded to each other
First 10 Alkanes in Series HydrocarbonMolecular Formula MethaneCH 4 EthaneC 2 H 6 PropaneC 3 H 8 ButaneC 4 H 10 PentaneC 5 H 12 HexaneC 6 H 14 SeptaneC 7 H 16 OctaneC 8 H 18 NonaneC 9 H 20 DecaneC 10 H 22
First 10 Alkenes in Series HydrocarbonMolecular Formula EtheneC 2 H 4 PropeneC 3 H 6 ButeneC 4 H 8 PenteneC 5 H 10 HexeneC 6 H 12 SepteneC 7 H 14 OcteneC 8 H 16 NoneneC 9 H 18 DeceneC 10 H 20 Notice: There is no alkene corresponding to the methane of the alkane series. That is b/c there must be at least 2 carbon atoms to form a double bond.
First 10 Alkynes in Series HydrocarbonMolecular Formula EthyneC 2 H 2 PropyneC 3 H 4 ButyneC 4 H 6 PentyneC 5 H 8 HexyneC 6 H 10 SeptyneC 7 H 12 OctyneC 8 H 14 NonyneC 9 H 16 DecyneC 10 H 18 Notice: There is no alkyne corresponding to the methane of the alkane series. That is b/c there must be at least 2 carbon atoms to form a triple bond.