Download
slide1 n.
Skip this Video
Loading SlideShow in 5 Seconds..
To get reactivity out of an organic molecule, functional groups have to be added. PowerPoint Presentation
Download Presentation
To get reactivity out of an organic molecule, functional groups have to be added.

To get reactivity out of an organic molecule, functional groups have to be added.

404 Views Download Presentation
Download Presentation

To get reactivity out of an organic molecule, functional groups have to be added.

- - - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

  1. Functional Groups • To get reactivity out of an organic molecule, functional groups have to be added. • Functional groups control how a molecule functions. • More complicated functional groups contain elements other than C or H (heteroatoms). • Functional group containing molecules can either be saturated (alcohols, ethers, amines etc.) or unsaturated (carboxylic acids, esters, amides, etc.). • We usually use R to represent alkyl groups.

  2. Alcohols • The functional group of an alcohol is an -OH group bonded to an sp3 hybridized carbon • bond angles about the hydroxyl oxygen atom are approximately 109.5° • Oxygen is sp3 hybridized • two sp3 hybrid orbitals form sigma bonds to carbon and hydrogen • the remaining two sp3 hybrid orbitals each contain an unshared pair of electrons

  3. Nomenclature-Alcohols • IUPAC names • the parent chain is the longest chain that contains the OH group • number the parent chain to give the OH group the lowest possible number • change the suffix -e to -ol • Common names • name the alkyl group bonded to oxygen followed by the word alcohol

  4. Nomenclature-Alcohols • Examples

  5. C H C H C H C H C H C H C H C H 3 2 2 2 2 2 H O O H O H O H H O H O O H 1,2-Ethanediol 1,2-Propanediol 1,2,3-Propanetriol (Ethylene glycol) (Propylene glycol) (Glycerol, Glycerine) Nomenclature of Alcohols • Compounds containing more than one OH group are named diols, triols, etc.

  6. Nomenclature of Alcohols • Unsaturated alcohols • show the double bond by changing the infix from -an- to -en- • show the the OH group by the suffix -ol • number the chain to give OH the lower number

  7. Physical Properties • Alcohols are polar compounds • they interact with themselves and with other polar compounds by dipole-dipole interactions • Dipole-dipole interaction:the attraction between the positive end of one dipole and the negative end of another

  8. Physical Properties • Hydrogen bonding:when the positive end of one dipole is an H bonded to F, O, or N (atoms of high electronegativity) and the other end is F, O, or N • the strength of hydrogen bonding in water is approximately 21 kJ (5 kcal)/mol • hydrogen bonds are considerably weaker than covalent bonds • nonetheless, they can have a significant effect on physical properties

  9. Hydrogen Bonding

  10. Physical Properties • In relation to alkanes of comparable size and molecular weight, alcohols • have higher boiling points • are more soluble in water • The presence of additional -OH groups in a molecule further increases solubility in water and boiling point

  11. Physical Properties

  12. Phenols • Alcohol with aromatic ring

  13. Phenols

  14. Phenols • Ingredients in cloves, vanillia, nutmeg, mint

  15. Thiols: Structure • The functional group of a thiol is an SH (sulfhydryl) group bonded to an sp3 hybridized carbon • The bond angle about sulfur in methanethiol is 100.3°, which indicates that there is considerably more p character to the bonding orbitals of divalent sulfur than there is to oxygen

  16. Nomenclature • IUPAC names: • the parent is the longest chain that contains the -SH group • change the suffix -e to -thiol • when -SH is a substituent, it is named as a sulfanyl group • Common names: • name the alkyl group bonded to sulfur followed by the word mercaptan

  17. bp (° C) bp (° C) M ethanethiol M ethanol E thanethiol E thanol Thiols: Physical Properties • Because of the low polarity of the S-H bond, thiols show little association by hydrogen bonding • they have lower boiling points and are less soluble in water than alcohols of comparable MW • the boiling points of ethanethiol and its constitutional isomer dimethyl sulfide are almost identical Thiol Alcohol 65 6 78 35 1-Butanethiol 1-Butanol 117 98

  18. Thiols: Physical Properties • Low-molecular-weight thiols = STENCH • the scent of skunks is due primarily to these two thiols • a blend of low-molecular weight thiols is added to natural gas as an odorant; the two most common of these are

  19. Ethers (R-O-R′) • Compounds in which two hydrocarbons linked by an oxygen are called ethers. • Ethers are commonly used as solvents.

  20. C H O H 3 C H O C C H C H C H O C H C H 3 3 3 2 2 3 C H O C H C H 3 2 3 Ethoxyethane trans- 2-Ethoxy- 2-Methoxy-2- (Diethyl ether) methylpropane cyclohexanol ( tert- Butyl methyl ether) Nomenclature: ethers • IUPAC: the longest carbon chain is the parent • name the OR group as an alkoxy substituent • Common names: name the groups bonded to oxygen in alphabetical order followed by the word ether

  21. Nomenclature: ethers • Although cyclic ethers have IUPAC names, their common names are more widely used • IUPAC: prefix ox- shows oxygen in the ring • the suffixes -irane, -etane, -olane, and -ane show three, four, five, and six atoms in a saturated ring

  22. Physical Properties • Although ethers are polar compounds, only weak dipole-dipole attractive forces exist between their molecules in the pure liquid state

  23. C H C H O H C H O C H 3 2 3 3 bp 78° C Physical Properties • Ethanol and dimethyl ether are constitutional isomers. • Their boiling points are dramatically different • ethanol forms intermolecular hydrogen bonds which increase attractive forces between its molecules resulting in a higher boiling point • there is no comparable attractive force between molecules of dimethyl ether Dimethyl ether Ethanol bp -24°C

  24. Physical Properties • Boiling points of ethers are • lower than alcohols of comparable MW • close to those of hydrocarbons of comparable MW • Ethers are hydrogen bond acceptors • they are more soluble in H2O than are hydrocarbons

  25. C H H C 3 H C C H 3 2 2 Oxirane cis- 2,3-Dimethyloxirane 1,2-Epoxycyclohexane C l C l (Ethylene oxide) ( cis- 2-Butene oxide) (Cyclohexene oxide) Epoxides • Epoxide: a cyclic ether in which oxygen is one atom of a three-membered ring • simple epoxides are named as derivatives of oxirane • where the epoxide is part of another ring system, it is shown by the prefix epoxy- • common names are derived from the name of the alkene from which the epoxide is formally derived H H 1 H 2 3 O C C O O 2 1 H O epichlorohydrine

  26. Crown Ethers • Crown ether:a cyclic polyether derived from ethylene glycol or a substituted ethylene glycol • the parent name is crown, preceded by a number describing the size of the ring and followed by the number of oxygen atoms in the ring

  27. Crown Ethers • The diameter of the cavity created by the repeating oxygen atoms is comparable to the diameter of alkali metal cations • 18-crown-6 provides very effective solvation for K+

  28. Thioethers • The sulfur analog of an ether • IUPAC name: select the longest carbon chain as the parent and name the sulfur-containing substituent as an alkylsulfanyl group • common name: list the groups bonded to sulfur followed by the word sulfide

  29. Disulfide • Disulfide: contains an -S-S- group • IUPAC name: select the longest carbon chain as the parent and name the disulfide-containing substituent as an alkyldisulfanyl group • Common name: list the groups bonded to sulfur and add the word disulfide

  30. Silyl Ethers

  31. Compounds with a Carbonyl Group • Carboxylic Acids • Carboxylic acids contain a carbonyl group with an -OH attached. • The carboxyl functional group is -COOH: • Carboxylic acids are weak acids. • Named like alkanes with “-oic acid” at the end. • Typical carboxylic acids are found in spinach, vinegar, cleaners, vitamin C, aspirin, and citrus fruits. • Carboxylic acids are also used to make polymers for fibers, paints, and films.

  32. Structure • The functional group of a carboxylic acid is a carboxyl group • the general formula for an aliphatic carboxylic acid is RCOOH; that for an aromatic carboxylic acid is ArCOOH

  33. Nomenclature - IUPAC • IUPAC names: drop the -e from the parent alkane and add the suffix -oic acid • if the compound contains a carbon-carbon double bond, change the infix -an- to -en-

  34. Nomenclature - IUPAC • The carboxyl group takes precedence over most other functional groups

  35. Nomenclature - IUPAC • dicarboxylic acids: add the suffix -dioic acid to the name of the parent alkane containing both carboxyl groups

  36. Nomenclature - IUPAC • if the carboxyl group is bonded to a ring, name the ring compound and add the suffix -carboxylic acid • benzoic acid is the simplest aromatic carboxylic acid • use numbers to show the location of substituents

  37. Nomenclature-Common • when common names are used, the letters etc. are often used to locate substituents

  38. Physical Properties • In the liquid and solid states, carboxylic acids are associated by hydrogen bonding into dimeric structures

  39. Physical Properties • Carboxylic acids have significantly higher boiling points than other types of organic compounds of comparable molecular weight • they are polar compounds and form very strong intermolecular hydrogen bonds • Carboxylic acids are more soluble in water than alcohols, ethers, aldehydes, and ketones of comparable molecular weight • they form hydrogen bonds with water molecules through their C=O and OH groups

  40. Physical Properties • Table 17.2

  41. Physical Properties • water solubility decreases as the relative size of the hydrophobic portion of the molecule increases

  42. EXERCICES

  43. Compounds with a Carbonyl Group • Aldehydes and Ketones • The carbonyl functional group is C=O. • Aldehydes must have at least one H atom attached to the carbonyl group: • Ketones must have two C atoms attached to the carbonyl group: • Aldehydes and ketones are prepared from the oxidation of alcohols.

  44. H C H C H C H C H C C H 3 3 3 Methanal Ethanal Propanone (Formaldehyde) (Acetaldehyde) (Acetone) Structure • the functional group of an aldehyde is a carbonyl group bonded to a H atom and a carbon atom • the functional group of a ketone is a carbonyl group bonded to two carbon atoms O O O

  45. Nomenclature • IUPAC names: • the parent chain is the longest chain that contains the functional group • for an aldehyde, change the suffix from -e to -al • for an unsaturated aldehyde, change the infix from -an- to -en-; the location of the suffix determines the numbering pattern • for a cyclic molecule in which -CHO is bonded to the ring, add the suffix -carbaldehyde

  46. Nomenclature: Aldehydes • the IUPAC retains the common names benzaldehyde and cinnamaldehyde, as well formaldehyde and acetaldehyde

  47. Nomenclature: Ketones • IUPAC names • the parent alkane is the longest chain that contains the carbonyl group • indicate the ketone by changing the suffix -e to -one • number the chain to give C=O the smaller number • the IUPAC retains the common names acetone, acetophenone, and benzophenone

  48. Common Names • for an aldehyde, the common name is derived from the common name of the corresponding carboxylic acid • for a ketone, name the two alkyl or aryl groups bonded to the carbonyl carbon and add the word ketone