Pharmaceutical Organic Chemistry I (PMC 102) 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 Pharmaceutical Organic Chemistry PMC 102 Dr. Asmaa Said Ali Yassen Quiz  04 Alkynes What is Alkynes? Nomenclature Physical Properties The acidity of terminal alkynes Reaction of acetylide anion Preparation Preparation Preparation Reactions Reactions Reactions Reactions Reactions Reactions THANK YOU Dr. Asmaa Said Ali Yassen [email protected] www.gu.edu.eg  Pharmaceutical Organic Chemistry I (PMC 102) Dr. Asmaa Yassen gu.edu.eg  03 Alkenes Unsaturated Hydrocarbons  What is Alkenes? Alkenes are hydrocarbons with carbon-to-carbon double bonds (R2C=CR2). They are called unsaturated hydrocarbons.  Nomenclature Here are some basic rules for naming alkenes from the International Union of Pure and Applied Chemistry (IUPAC): 1. The longest chain of carbon atoms containing the double bond is considered the parent chain. It is named using the same stem as the alkane having the same number of carbon atoms but ends in -ene to identify it as an alkene. Thus the compound CH2=CHCH3 is propene. 2. If there are four or more carbon atoms in a chain, we must indicate the position of the double bond. The carbons atoms are numbered so that the first of the two that are doubly bonded is given the lower of the two possible numbers. The compound CH3CH=CHCH2CH3, for example, has the double bond between the second and third carbon atoms. Its name is 2-pentene (not 3-pentene). 3. Substituent groups are named as with alkanes, and their position is indicated by a number. Note that the numbering of the parent chain is always done in such a way as to give the double bond the lowest number, even if that causes a substituent to have a higher number. The double bond always has priority in numbering. Thus, the structure below is 5-methyl-2-hexene. Classification Physical Properties  Isomers 1. Structural Isomers A structural isomer is one in which two or more organic compounds have the same molecular formulas, but different structures. 2. Geometric Isomers Geometric isomers are isomers in which the order of atom bonding is the same, but the arrangement of atoms in space is different. Geometry of double bond If the alkene is trisubstituted or tetrasubstituted, the(E)– (Z)system is used. Compare the group of higher priority on one carbon atom with the group of higher priority on the other carbon atom. If the two groups of higher priority are on the same side of the double bond, the alkene is designated(Z). If the two groups of higher priority are on opposite sides of the double bond, the alkene is designated(E). Compare the atoms attached to them based on their atomic numbers. Stability of Alkene Stability of Alkene Preparation From Alkyl halides (Elimination) From Alcohols ( Elimination)  From Vic-dihalides (Dehalogenation) If the halogens are bonded to adjacent carbons = Vicinal If two halogens are bonded to the same carbon = Geminal From Alkynes (Hydrogenation) Reactions Markovnikov’s Rule Thank You