Alkenes

Babylon University / Pharmacy Collage

Department of Pharmaceutical Chemistry

Monday.. 1/3/2018


(Lecture No. 4,5 : Alkanes )

Classification by structure: the family
The basis of organic chemistry, we have said, is the structural theory. We separate all organic compounds into a number of families on the basis of structure.
Having done this, we find that we have at the same time classified the compounds as to their physical and chemical properties. A particular set of properties is thus characteristic of a particular kind of structure.

Structure of ethane
Next in size after methane is ethane, C2H6 . If we connect the atoms of this, molecule by covalent bonds, following the rule of one bond (one pair of electron), for each hydrogen and four bonds (four pairs of electrons) for each carbon, we arrive at the structure :


Each carbon is bonded to three hydrogens and to the other carbon. Since each carbon atom is bonded to four other atoms, its bonding orbitals (sp³ orbitals) are directed toward the corners of a tetrahedron. As in the case of methane, the carbon-hydrogen bonds result from overlap of these sp³ orbitals, with the s orbitals of the hydrogens. The carbon-carbon bond arises from overlap of two sp³ orbitals.
The carbon-hydrogen and carbon-carbon bonds have the same general electron distribution, being cylindrically symmetrical about a line joining the atomic nuclei ; because of this similarity in shape, the bonds are given the same name, a bonds (sigma bonds).
Babylon University / Pharmacy Collage

Department of Pharmaceutical Chemistry

Monday.. 1/3/2018


(Lecture No. 4,5 : Alkanes )

Classification by structure: the family
The basis of organic chemistry, we have said, is the structural theory. We separate all organic compounds into a number of families on the basis of structure.
Having done this, we find that we have at the same time classified the compounds as to their physical and chemical properties. A particular set of properties is thus characteristic of a particular kind of structure.

Structure of ethane
Next in size after methane is ethane, C2H6 . If we connect the atoms of this, molecule by covalent bonds, following the rule of one bond (one pair of electron), for each hydrogen and four bonds (four pairs of electrons) for each carbon, we arrive at the structure :


Each carbon is bonded to three hydrogens and to the other carbon. Since each carbon atom is bonded to four other atoms, its bonding orbitals (sp³ orbitals) are directed toward the corners of a tetrahedron. As in the case of methane, the carbon-hydrogen bonds result from overlap of these sp³ orbitals, with the s orbitals of the hydrogens. The carbon-carbon bond arises from overlap of two sp³ orbitals.
The carbon-hydrogen and carbon-carbon bonds have the same general electron distribution, being cylindrically symmetrical about a line joining the atomic nuclei ; because of this similarity in shape, the bonds are given the same name, a bonds (sigma bonds).
Babylon University / Pharmacy Collage

Department of Pharmaceutical Chemistry

Monday.. 1/3/2018


(Lecture No. 4,5 : Alkanes )

Classification by structure: the family
The basis of organic chemistry, we have said, is the structural theory. We separate all organic compounds into a number of families on the basis of structure.
Having done this, we find that we have at the same time classified the compounds as to their physical and chemical properties. A particular set of properties is thus characteristic of a particular kind of structure.

Structure of ethane
Next in size after methane is ethane, C2H6 . If we connect the atoms of this, molecule by covalent bonds, following the rule of one bond (one pair of electron), for each hydrogen and four bonds (four pairs of electrons) for each carbon, we arrive at the structure :


Each carbon is bonded to three hydrogens and to the other carbon. Since each carbon atom is bonded to four other atoms, its bonding orbitals (sp³ orbitals) are directed toward the corners of a tetrahedron. As in the case of methane, the carbon-hydrogen bonds result from overlap of these sp³ orbitals, with the s orbitals of the hydrogens. The carbon-carbon bond arises from overlap of two sp³ orbitals.
The carbon-hydrogen and carbon-carbon bonds have the same general electron distribution, being cylindrically symmetrical about a line joining the atomic nuclei ; because of this similarity in shape, the bonds are given the same name, a bonds (sigma bonds).