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Organic Chemistry

Organic Chemistry. Carbon-containing Compounds and their Properties. Organic Compounds. Contain carbon atoms, often several per molecule Possibly derived from living sources About 90% of the known substances are organic. Most of these contain only a few kinds of elements: C, H, O, N, S

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Organic Chemistry

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  1. Organic Chemistry Carbon-containing Compounds and their Properties

  2. Organic Compounds • Contain carbon atoms, often several per molecule • Possibly derived from living sources • About 90% of the known substances are organic. Most of these contain only a few kinds of elements: C, H, O, N, S • Most intramolecular bonding is covalent

  3. Organic Compounds • Many organic substances are flammable • Frequently, more than one substance of same overall formula – isomers • Important biomolecules are organic • lipids, carbohydrates, proteins, hormones, nucleic acids, etc

  4. Flammable C,H + O2  CO2 + H2O + energy Since organic substances contain C (and almost always H), combustion occurs forming CO2 and water

  5. H3CCHCH3 OH Isomers–Example:C3H8O H3CCH2CH2OH bp=97°C bp=82°C H3COCH2CH3 bp=8°C

  6. Organic Families • Millions of organic compounds exists • Grouped in families to correlate similar properties and to predict chemical and physical behaviors • Families are based on similar molecular structures, especially similar functional groups

  7. Organic Families • Functional groups • Sub-molecular units that are responsible for particular chemical and physical properties • May be single atoms; often are several atoms joined together • Molecules may contain several functional groups (or none) • Chemical Reactions often occur (or can be “designed”) that affect only certain functional groups, leaving much of molecular structure unaffected

  8. Organic Families • Molecules containing only C and H atoms with only single bonds are considered to have no functional group • Alkanes, a type of hydrocarbon • Still, these molecules can react; they undergo oxidation, or combustion, for example

  9. H H H C H H H CCH H H H Alkanes Methane, the simplest of alkane; meth–from “wood,” as in “wood alcohol,” or methanol, containing one carbon atom per molecule Ethane, the two-carbon alkane; eth–from “ether”; the ether of anesthesia is made from two-carbon molecules

  10. H H H C H H H CCH H H H Alkanes Also, CH4 Methane Or, C2H6, or, CH3CH3 Ethane

  11. H H H H CCCH H H H H H H H H CCCCH H H H H Alkanes Propane, the three-carbon alkane; pro–from “first” or “propanoic acid,” simplest 3-carbon fatty acid Butane, the four-carbon alkane; but–from“butter”; butyric acid, containing 4 carbons and named for butter, forms as butter sours

  12. H H H H CCCH H H H H H H H H CCCCH H H H H Alkanes Or, C3H8, or CH3CH2CH3 Propane C4H10 CH3CH2CH2CH3 Butane

  13. H H H H H H CCCCCH H H H H H Alkanes C5H12 CH3CH2CH2CH2CH3 Pentane, the five-carbon alkane; pent–for “five” as in “pentagon”

  14. H H H H H H H H CCCCCCCCH H H H H H H H H Alkanes H C8H18 CH3CH2CH2CH2CH2CH2CH2CH3 Octane, the 8-carbon alkane; oct–for “eight” as in “octet” or “octagon”

  15. H H3CCCH3 CH3 H H C H Alkanes Methylpropane, =“methyl,” an alkyl group Or CH3 or CH3

  16. CH3 H3CCCH2CH3 CH3 CH3 H3CCH2CCH3 CH3 Alkanes 2,2-dimethylbutane 2,2-dimethylbutane

  17. CH2CH3 H3CCHCH2CH2CH3 CH3 Alkanes 3-ethyl-2-methylpentane

  18. CH2 CH2 H2C CH2 H2C CH3 CH3 CH3 Alkanes Cyclopentane = 1,1,3-trimethylcyclohexane

  19. H H C=C H H H H H C H C=C H H Alkenes Contain one or more C=C double bonds Ethene, the simplest of alkenes H2C=CH2 Propene, the three-carbon alkene CH3CH=CH2

  20. CH3 H C=C CH2CH3 H CH3 CH2CH3 C=C H H Alkenes Contain one or more C=C double bonds CH3CH2CH=CH2 1-Butene H2C=CHCH2CH3 1-Butene cis-2-Pentene trans-2-Pentene

  21. CH3 CH3CCCHCH3 Alkynes Contain one or more CC triple bonds CH3CH2CCH 1-Butyne HCCCH2CH3 1-Butyne 1 2 3 4 5 4-Methyl-2-pentyne

  22. H H3CCCH3 OH = “OH,” an alcohol group CH3 CH3CH2CCH2CH3 OH AlcoholsContain –OH functional group 2-Propanol, 3-Methyl-3-pentanol

  23. O = CH3CH2C H =“CHO,”an aldehyde group Similar to aldehyde but not at end of molecule CH3CH2CCH2CH3 = O Aldehydes and KetonesContain C=O functional group Propanal, an aldehyde 3-Pentanone, a ketone

  24. O = O = HCC-CH2-C-CH3 Aldehydes and KetonesContain C=O functional group Cyclohexanone 4-Pentyn-2-one (also, alkyne-like)

  25. Physical Properties • Such as – • Boiling point, melting point • Usual state of matter (solid, liquid, gas)? • Solubility characteristics • Relate to and Predictable from Molecular Structure

  26. Boiling Point • Temperature where liquid begins to evaporate rapidly (bubbles readily form in liquid) • Higher bp for larger molecules • Very large molecules usually result in solid material

  27. Boiling Point • FW<60 g/mol: usually gases • FW between 60 and 300: liquids • FW>300: solids C4H10, bp = -0.5°C (FW = 58) C8H17Br, bp = 200°C (FW = 193) C20H42, mp = 37°C (FW = 283)

  28. CH3 H3CCCH3 H H H H H CH3 H CCCCCH H H H H H Boiling, Melting Points • Shape influences • More compact, symmetrical molecules have lower bp but higher mp bp = 36°C, mp = -130°C bp = 10°C, mp = -17°C Both have FW = 72, C5H12

  29. Boiling Point • H-Bonding increases bp • Especially noticeable for smaller molecules H2O, bp = 100°C (FW = 18, H-bonded) O2, bp = -183°C (FW = 32, no H-bonding) C2H5OH, bp = 78°C (FW = 46, H-bonded) C2H5F, bp = -32°C (FW = 48, no H-bonding)

  30. Organic Chemical Reactions • Types of changes usually predictable by the functional group(s) present in the molecules • Often, reactions can be “directed” to occur to specific functional groups, even when several groups are present • Biological reactions almost always catalyzed by enzymes

  31. Example Reactions -- Alkanes • Least reactive of all families • Combustion and other oxidations are typical reactions C3H8 + 5 O2  3 CO2+ 4 H2O CH4 + Cl2  CH3Cl + HCl

  32. CH3 H3C + H2 CH3–CH2–CH2–CH3 C=C H H Example Reactions -- Alkenes • Many reactions change C=C to C–C • Additions

  33. CH2Br H3C CH3 H3C C=C h + Br2 + HBr C=C H H H H Example Reactions -- Alkenes • Many reactions change C=C to C–C • Some reactions affect C–H adjacent to double bond -- substitutions

  34. H’s involved in oxidation Example Reactions -- Alcohols • –OH is site of reactivity • Oxidations, dehydrations, additions are common H3CCH2CH2OH

  35. HOH(H2O) involved in dehydrations Example Reactions -- Alcohols • –OH is site of reactivity • Oxidations, dehydrations, additions are common H3CCH2CH2OH

  36. OH involved in additions Example Reactions -- Alcohols • –OH is site of reactivity • Oxidations, dehydrations, additions are common H3CCH2CH2OH

  37. * * H3CCH2CH2OH + [O]xidizer H3CCHC=O + H2[O]xidizer H Example Reactions -- Alcohols • –OH is site of reactivity • Oxidations, dehydrations, additions are common

  38. * * H3CCH2CH2OH + catalyst H3CCH2=CH2 Example Reactions -- Alcohols • –OH is site of reactivity • Oxidations, dehydrations, additionsare common HOH(H2O) involved in dehydrations

  39. O = * * H3CCH2CH2OH + CH3C H3CCH2–CH2–O–CCH3 + H2O – O–H O = Example Reactions -- Alcohols • –OH is site of reactivity • Oxidations, dehydrations, additions are common An ester. Reaction is reversible.

  40. H HO2CCH2CCO2H + [O]  HO2CCH2CCO2H + H2[O] OH = O Example Reactions -- Alcohols • Oxidation of alcohol in Citric acid Cycle “Malate” to “Oxaloacetate”

  41. H HO2CCHCHCO2H OH Example Reactions -- Alkenes • Addition in Citric acid Cycle HO2CCH=CHCO2H + H2O  “Fumarate”to“Malate”

  42. Amines • Contain nitrogen, N • Are usually basic, similar to ammonia, NH3 • React with acids CH3NH2 methylamine (CH3CH2)2NH N,N-diethyl amine

  43. O = H3CCH2CH2NH2 + CH3C H3CCH2–CH2–N–CCH3 + H2O – O–H O = H An amide; also, called peptide in biological systems Amines • React with organic acids to form amides • Reactions occur indirectly or by means of enzymes

  44. O O O R R' R = = = CCHNH2 CCHNH2 CCHN – – – O–H O–H O–H R' O = CCHNH2 H Proteins • Polymeric amides, or “polypeptides” • Formed from amino acids + + H2O A dipeptide R and R'contain H and often C, N, O, and/or S

  45. R3 R3 R4 R2 R3 R3 R1 R1 R2 R2 R2 R4 R4 H2N–CH–CO–NH–CH–CO–NH–CH–CO–NH–CH–CO CH–CO–NH–CH–CO–NH–CH–CO2H NH–CH–CO–NH–CH–CO –NH–CO–CH NH–CO–CH–NH–CO–CH–NH–CO–CH–NH– Proteins A tridecapeptide (13 amino acid units)

  46. O = CCH2R' – O–H Esters • Can be formed from acids and alcohols • Provide many natural fruit flavors and essences • Basis of simple fats, or triglycerides R–OH + + H2O R–O2C–CH2–R' An ester

  47. O = CH2–O–C–R O O = = CH2–O–C–R" CH–O–C–R' Simple Fats -- Triglycerides

  48. O = CH2–O–C–R “Fatty acid” fragments O O = = CH2–O–C–R" CH–O–C–R' Simple Fats -- Triglycerides Glycerol “backbone”

  49. O = CH2–O–C–R O O = = CH2–O–C–R" CH–O–C–R' Simple Fats -- Triglycerides + H2O  (& enzymes)

  50. CH2OH O = CHOH CH2–O–C–R CH2OH + H2O  (& enzymes) O O = = CH2–O–C–R" CH–O–C–R' Simple Fats -- Triglycerides Glycerol + RCO2H R'CO2H Fatty acids R "CO2H

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