Chapter 5, Chem PDF - Lecture Notes

College of Medicine – ‫ﻛﻠﯾﺔ اﻟطب‬ Un-Saturated Hydrocarbons “ALKENES & ALKYNES” College of Medicine – ‫ﻛﻠﯾﺔ اﻟطب‬ After this lecture, the student will be able to: } Describe the structural characteristics of alkenes. } Define the structural characteristics of alkynes } Explain the IUPAK system in na...

College of Medicine – ‫ﻛﻠﯾﺔ اﻟطب‬ Un-Saturated Hydrocarbons “ALKENES & ALKYNES” College of Medicine – ‫ﻛﻠﯾﺔ اﻟطب‬ After this lecture, the student will be able to: } Describe the structural characteristics of alkenes. } Define the structural characteristics of alkynes } Explain the IUPAK system in naming alkenes & alkynes } Explain the hybridization in alkenes & alkynes } Identify the meaning of unsaturated organic compound } Identify some un-saturated compounds in our life College of Medicine – ‫ﻛﻠﯾﺔ اﻟطب‬ An organic compound that contains double or triple carbon-carbon bonds is called an unsaturated compound The ratio of the hydrogen atoms to carbon atoms is lower in an unsaturated compound than in a saturated compound College of Medicine – ‫ﻛﻠﯾﺔ اﻟطب‬ An alkene is a hydrocarbon that contains one or more carbon-carbon double covalent bonds, with formula At least one carbon-carbon bond in an alkene is a double covalent bond. Other bonds may be single carbon-carbon bonds and carbonhydrogen bonds. College of Medicine – ‫ﻛﻠﯾﺔ اﻟطب‬ } Ethene (C2H4) is the simplest alkene It is often called by the common name ethylene College of Medicine – ‫ﻛﻠﯾﺔ اﻟطب‬ Find the longest carbon chain Enumerate the carbons such that the functional group, here the double bond, gets the lowest possible number Substituents are cited before the parent longest chain, along with a number indicating its position at the chain College of Medicine – ‫ﻛﻠﯾﺔ اﻟطب‬ College of Medicine – ‫ﻛﻠﯾﺔ اﻟطب‬ College of Medicine – ‫ﻛﻠﯾﺔ اﻟطب‬ College of Medicine – ‫ﻛﻠﯾﺔ اﻟطب‬ College of Medicine – ‫ﻛﻠﯾﺔ اﻟطب‬ Trigonal planar geometry around each carbon atom The molecular orbitals of Ethene:   1s orbitals of the four hydrogen atoms 2s, 2px, 2py, and 2pz orbitals of the two carbon atoms Ethene College of Medicine – ‫ﻛﻠﯾﺔ اﻟطب‬ College of Medicine – ‫ﻛﻠﯾﺔ اﻟطب‬ A trigonal planar atom has sp2 hybridization College of Medicine – ‫ﻛﻠﯾﺔ اﻟطب‬ A trigonal planar atom has sp2 hybridization College of Medicine – ‫ﻛﻠﯾﺔ اﻟطب‬ Pi bond overlapping: side by side College of Medicine – ‫ﻛﻠﯾﺔ اﻟطب‬ College of Medicine – ‫ﻛﻠﯾﺔ اﻟطب‬ College of Medicine – ‫ﻛﻠﯾﺔ اﻟطب‬ College of Medicine – ‫ﻛﻠﯾﺔ اﻟطب‬ A hydrocarbon that contains one or more carbon-carbon triple covalent bonds is called an alkyne At least one carbon-carbon bond in an alkyne is a triple covalent bond. Other bonds may be single or double carboncarbon bonds and carbon-hydrogen bonds. ◦ Like alkenes, alkynes are unsaturated compounds. College of Medicine – ‫ﻛﻠﯾﺔ اﻟطب‬ } } } Alkynes are not plentiful in nature. The simplest alkyne is the gas ethyne (C2H2), which has the common name acetylene, and is shown at left. The triple bond restricts rotation in an ethyne molecule, which has a linear shape. College of Medicine – ‫ﻛﻠﯾﺔ اﻟطب‬ The method for naming alkynes is analogous to the naming of alkenes. However, the suffix is -yne rather than -ene. 4-methyl-2-pentyne College of Medicine – ‫ﻛﻠﯾﺔ اﻟطب‬ College of Medicine – ‫ﻛﻠﯾﺔ اﻟطب‬ College of Medicine – ‫ﻛﻠﯾﺔ اﻟطب‬ College of Medicine – ‫ﻛﻠﯾﺔ اﻟطب‬ Ichthyothereol is a toxic polyyne compound found in the leaves and flowers of several plants in South and Central America fish poison,,,,,,,,,,,,,??????? College of Medicine – ‫ﻛﻠﯾﺔ اﻟطب‬