Chemistry- JIB Organic Chemistry

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  • 1. Unit 6: Organic Chemistry
    • Cover introduction, alkanes, & cycloalkanes
    • There will be two quizzes
  • 2. Standards Covered Today:
    • 1. Describe the features of a homologous series.
    • 2. State names and draw structural formulas for organic compounds using the IUPAC Naming System.
    • 3. Draw structural formulas and state names of non-cyclic (straight chain) alkanes up to C 10 , including isomers.
    • 4. Draw structural formulas and state names of cyclic structures up to C 10
  • 3. Introduction
    • In all organic compounds,
      • all carbon atoms must make four bonds,
      • all oxygen atoms must make two bonds,
      • all nitrogen atoms must make three bonds,
      • all hydrogen atoms must make one bond,
      • and all halogens must make one bond.
  • 4. Names of Structures
    • Lewis Structures
    • Structural Formulas
    • Condensed Formulas & Structures
    • Line Structures
    C 6 H 14 or CH 3 (CH 2 ) 4 CH 3
  • 5. Notes on Structures
    • Structural Formula: shows all bonds including hydrogen
    • Condensed Formula: These are generally written without lines indicating bonds, or showing lone pairs, and parentheses are used for identical groups.
    • Line Formula: Bonds are represented by lines, carbon atoms are assumed to be present at the start and finish of a line.
      • Nitrogen, oxygen and halogens are labeled, but hydrogens are only shown when bonded to a drawn atom.
      • Each atom is assumed to have sufficient hydrogen atoms around it to make it neutral.
  • 6. Isomers
    • Draw a structural formula for C 4 H 10
    • An isomer is a compound that has the same molecular formula as another.
    • Structural Isomers : these are isomers that differ in their bonding sequence. They have different bond connectivity.
  • 7. Introduction to Nomenclature of Organic Molecules
    • Four Categories:
      • Alkanes
      • Alkenes
      • Alkynes
      • Cyclic Structures
  • 8. Alkanes
    • Alkanes are the simplest organic molecules, they only contain C and hydrogen, and only contain single bonds.
      • Considered to be hydrocarbons
    • Compounds that have the maximum number of bonded hydrogens, are said to be saturated.
      • Therefore, alkanes are the most saturated compounds
    • General Formula: C n H 2n + 2
  • 9. Nomenclature for compounds
    • The root name of the compound is based upon the number of carbon atoms in the longest continuous chain .
    Number of C atoms Root 1 Meth- 2 Eth- 3 Prop- 4 But- 5 Pent- 6 Hex- 7 Hept- 8 Oct- 9 Non- 10 Dec-
  • 10.
    • Any series that differs only by an increasing number of –CH 2 - groups is known as a homologous series . The individual members are said to be homologs of each other.
      • The series must contain the same functional group.
  • 11. IUPAC Naming System: Alkanes
    • 1) Find the longest continuous chain of carbon atoms. This is the base name of the compound.
    • 2) Number the longest chain beginning with the end nearest a substituent.
    • 3) Name the substituent groups attached to the longest chain as alkyl groups. Also state the location of each alkyl group according to its numbered carbon on the main chain.
    • 4) When two or more substituents are present, list them in alphabetical order. If two or more of the same alkyl groups are present, use the prefixes di-, tri- etc. to avoid repetition.
  • 12. Alkane Nomenclature Examples
    • 1)
    3-methyl hexane
    • If there are two chains of equal length, choose the chain that has the highest number of substituents.
  • 13.
    • Numbering starts at the end nearest a substituent so that the alkyl substituents have as low numbers as possible.
    Alkyl groups are named by replacing the –ane suffix of the alkane name with –yl. E.g. CH 3 CH 3 Ethane CH 3 CH 2 - Ethyl group CH 3 CH 2 CH 3 PropaneCH 3 CH 2 CH 2 - Propyl group
  • 14.
    • Prefixes are used when there are more than one type of alkyl substituent.
      • Di = 2
      • Tri = 3
      • Tetra = 4
      • Penta = 5
    • The prefixes do not count when alphabetizing.
  • 15. 3-ethyl-2,4,5-trimethylheptane
  • 16. Recognizing Types of Substitution
  • 17. Cycloalkanes
    • Cycloalkanes are simply alkanes that are cyclic.
      • Just add cyclo-before their name.
      • Notice the general formula for cycloalkanes is C n H 2n
  • 18. Two simple rules of cycloalkanes
    • Rule A: Decide whether the cyclic or acyclic (non-cyclic) portion contains more carbons. This determines the base name. (Alkyl substituted cycloalkane or cycloalkane substituted alkane).
    • Rule B: Carbons are numbered to give the lowest numbers for substituted carbons.
  • 19.
    • Numbering starts at the most substituted carbon, and goes around in order to give the lowest numbers.
    1,1,3-trimethylcyclopentane
    • When there are more acyclic than cyclic carbons, the cyclic part becomes a cycloalkyl substituent.
    4-cyclopropyl-3-methyloctane
  • 20. Complex Substituents
    • These are named as follows:
    • (a) The base alkyl group is numbered staring with the carbon bonded to the main chain.
    • (b)The substituents are listed with the appropriate numbers, and parentheses are used to separate the substituent name.
  • 21. Examples
    • Draw structures for the following compounds:
      • 1.) 3-ethyl-3-methylpentane
      • 2.) 3-methyl-5-propylnonane
      • 3.) 2,2,4,4-tetramethylhexane
      • 4.) pentylcyclohexane
      • 5.) 2,3-dimethyl-4-propylnonane
    • Give the IUPAC names of the following alkanes:
      • 1.) (CH 3 ) 2 CHCH 2 CH(C 2 H 5 )C(CH 3 ) 3
      • 2.)
    3.) (CH 3 CH 2 ) 3 CH 4.) (CH 3 ) 2 CH(CH 2 ) 3 CH 3
  • 22. Physical Properties of Alkanes
    • Nonpolar
    • What type of intermolecular forces?
    • Since weak interactions….so low boiling point and melting point
    • As molecular weight increases, interactions increase
    • As interactions b/w molecules increase, so does the strength of the interactions….
    • So what conclusions can we make?
    Dispersion Forces
  • 23.
    • The higher molecular weights…..
    • The more branches…
    Leads to liquids, then solids More compact structure, surface area decreases Less contact between molecules, dispersion forces decrease, so lower boiling point
  • 24. Try these:
    • Arrange in increasing boiling point:
    • CH 3 CH 2 CH 2 CH 3 , CH 3 CH 2 CH 2 CH 2 CH 2 CH 3 , CH 3 (CH 2 ) 8 CH 3
    • CH 3 (CH 2 ) 6 CH 3 , CH 3 C(CH 3 ) 2 CH 2 CH(CH 3 ) 2 ,
    • CH3CHCH3(CH 2 ) 4 CH 3
    • c. 2-methyl butane, 2,2-dimethylpropane, pentane
  • 25.
    • Alkene and Alkyne Nomenclature
    • Make sure you study the different functional groups over the break (sheet of paper with table on it)
    • This will need to be memorized for the quiz and test.
    • Quiz when we get back!
  • 26. Elements of Unsaturation
    • A saturated hydrocarbon: C n H 2n+2
    • Each multiple bond (and each ring) decreases the number of H’s by two.
    • Each of these is an element of unsaturation.
    • To calculate: find number of H’s if it were saturated, subtract the actual number of H’s, then divide by 2.
  • 27. Propose a Structure for C 5 H 8
    • First calculate the number of elements of unsaturation.
    • Remember:
      • A double bond is one element of unsaturation.
      • A ring is one element of unsaturation.
      • A triple bond is two elements of unsaturation.
  • 28. Alkene Nomenclature
    • Parent is longest chain containing the double bond.
    • -ane changes to -ene. (or -diene, -triene)
    • Number the chain so that the double bond has the lowest possible number.
    • In a ring, the double bond is assumed to be between carbon 1 and carbon 2.
  • 29. Try these: 1-butene 2-methyl-2-butene 3-methylcyclopentene 2-(1-methyl propyl)-1,3-cyclohexadiene 3-propyl-1-heptene
  • 30. Geometric Isomerism
    • Similar groups on same side of double bond, alkene is cis.
    • Similar groups on opposite sides of double bond, alkene is trans.
    trans -2-pentene cis -1,2-dibromoethene
  • 31. Alkynes
    • Alkynes contain a triple bond.
    • General formula is C n H 2n-2
    • Two elements of unsaturation for each triple bond.
  • 32. Alkyne Nomenclature
    • Find the longest chain containing the triple bond.
    • Change -ane ending to -yne .
    • Number the chain, starting at the end closest to the triple bond.
    • Give branches or other substituents a number to locate their position.
  • 33. Try these propyne 5-bromo-2-pentyne 3-methyl-1-hexyn-5-ene
  • 34. Practice Problems
    • Two worksheets
  • 35. Agenda
    • Review of alkanes, alkenes, alkynes, & cyclic structures
    • Nomenclature of Functional Groups
  • 36. Alcohols
    • Simple alcohols are named as derivatives of the parent alkane, using the suffix -ol , using the following simple rules:
    • Select the longest continuous carbon chain, containing the hydroxyl group, and derive the parent name by replacing the -e ending with -ol.
    • Number the carbon chain, beginning at the end nearest to the hydroxyl group.
    • Number the substituents and write the name, listing substituents alphabetically.
  • 37. Alcohol Examples
  • 38. Ether Nomenclature
    • Simple ethers are named either by identifying the two organic residues and adding the word ether .
    CH 3 —O—CH 3 Dimethyl ether CH 3 CH 2 OCH 2 CH 3 Diethyl ether
  • 39. Aldehydes Nomenclature
    • Aldehydes are named by replacing the terminal -e of the parent alkane with the suffix -al
    • The parent chain selected must contain the carbonyl group.
    • Number the carbon chain, beginning at the end nearest to the carbonyl group.
  • 40. Aldehyde Example methanal butanal 2-methyl butanal
  • 41. Ketone Nomenclature
    • The suffix for ketones is -one.
    • The parent chain selected must contain the carbonyl group.
    • Number the carbon chain, beginning at the end nearest to the carbonyl group.
  • 42. Ketone Examples 3-pentanone propanone 3-methyl-2-butanone
  • 43. Carboxylic Acid Nomenclature
    • Simple carboxylic acids are named as derivatives of the parent alkane, using the suffix -oic acid
    • Select the longest continuous carbon chain, containing the carboxylic acid group, and derive the parent name by replacing the -e ending with -oic acid.
    • Number the carbon chain, beginning at the end nearest to the carboxylic acid group.
    • Number the substituents and write the name, listing substituents alphabetically.
    • Carboxylic acid substituents attached to rings are named using the suffix -carboxylic acid.
  • 44. Carboxylic Acid Examples
  • 45. Ester Nomenclature
    • Esters are named by replacing the terminal of end with the suffix -oate
    • The parent chain selected must contain the
    • Number the end of the carbon chain (after the second O), and give it an –yl ending.
    • Practice Problems
  • 46. Amine Nomenclature
    • RNH 2 , R 2 NH, R 3 N
    • In amines, a nitrogen is bonded to one, two or three carbon atoms.
    • Practice Problems
  • 47. Functional Groups as Isomers
    • Some functional groups can exist as isomers of each other.
    • Example: C 4 H 8 O 2
  • 48. Try the following: