Pharmaceutical Organic Chemistry I Lecture 2 (12 OCT) PDF

Pharmaceutical Organic Chemistry I (PMC 102) Dr. Asmaa Yassen gu.edu.eg Quiz  02 Alkanes  What is Alkane? Saturated Hydrocarbons General formula: CnH2n+2. contain only single bonds Names of Small Hydrocarbons No. of Carbons Formula Name (CnH2n+...

Pharmaceutical Organic Chemistry I (PMC 102) Dr. Asmaa Yassen gu.edu.eg Quiz  02 Alkanes  What is Alkane? Saturated Hydrocarbons General formula: CnH2n+2. contain only single bonds Names of Small Hydrocarbons No. of Carbons Formula Name (CnH2n+2) 1 Methane CH4 2 Ethane C2H6 3 Propane C3H8 4 Butane C4H10 5 Pentane C5H12 6 Hexane C6H14 7 Heptane C7H16 8 Octane C8H18 9 Nonane C9H20 10 Decane C10H22 Methane, Ethane, Propane & Butane Alkane Alkyl group CH4 CH3 - Methane Methyl CH3CH3 CH3CH2 Ethane Ethyl H3C CH3 H3C C H2 H3C CH3 Propane propyl isopropyl CH3 CH2 CH3 H3C H3C H3C butane butyl sec-butyl CH3 CH3 CH3 H3C CH3 H3C CH3 H3C CH2 isobutane isobutyl tert-butyl Nomenclature of substituted alkanes Names of Common Substituent Groups What is the name for the following compound?  Physical Properties of Alkanes 1. C1-C5 are gases at room temperature. 2. C6-C10 are Liquids. 3. Higher that C11 are semisolids or waxy matters. 4. Because they are non-polar, alkanes are insoluble in water but soluble in no- polar solvents. 5. Boiling points of liquid alkanes increase with increase molecular weight (increase with increasing number of carbons (more atoms, more electrons, more opportunities for induced dipole-induced dipole forces ). 6. Boiling points decreases with chain branching. As branching increases, the distances between the molecules increased and hence the Van-der Waal forces decreased leading to lowering the boiling point of the branched alkanes. Preparation  Cycloalkanes are a class of hydrocarbons with carbon atoms connected in a ring structure. Formula: CnH2n The physical properties of cycloalkanes exhibit similarity to those of alkanes with open chains. Cycloalkanes exhibit a higher level of reactivity in comparison to alkanes because of angle strain in ring.  Angle Strain Angle strain is the increase in potential energy of a molecule due to bond angles deviating from the ideal values. The ideal angle for cycloalkanes is 109.5°. cyclopropane is more highly strained, more unstable and more reactive and undergoes reaction. Cyclopentane (Bond angle = 108° ) and cyclohexane (Bond angle = 109.5 ° ) are not strained, stable. So, they are not reactive. The reactions of the cycloalkanes are generally just the same as the alkanes, with the exception of the very small ones - particularly cyclopropane. In the presence of UV light, cyclopropane will undergo substitution reactions with chlorine or bromine just like a non-cyclic alkane. Thank You