Medical Chemistry - Alkanes Lecture Notes PDF

Medical Chemistry Almaaqal University Collage of Dentistry Alkanes Dr/ Wael Sobhy Darwish Lec-8 1ST stage&2024  Organic Chemistry Def...

Medical Chemistry Almaaqal University Collage of Dentistry Alkanes Dr/ Wael Sobhy Darwish Lec-8 1ST stage&2024  Organic Chemistry Definition is the study of the structure, properties, composition, reactions, and preparation of carbon-containing compounds. Most organic compounds contain carbon and hydrogen, but they may also include any number of other elements (e.g., nitrogen, oxygen, halogens, phosphorus, silicon, sulfur).  Classification of organic compounds 1- Aliphatic hydrocarbons 2- Aromatic hydrocarbons.  Aliphatic hydrocarbons: These are the compounds, drawn in an open- chain format. They can be classified into two types: Saturated compounds. Unsaturated compounds. Saturated compounds: Saturated compounds are those in which two carbon atoms are linked together only via a single bond.  Alkanes Definition are organic compounds that consist of single-bonded carbon and hydrogen atoms and lack any other functional groups. All alkanes have the formula CnH2n+2 The simplest alkane is methane. Alkanes with unbranched carbon chains are called normal alkanes. Each member of the series differs from the next higher and the next lower member by -CH2 group (methylene group).  Sources of alkanes The principle sources of alkanes are natural gas and petroleum. Natural gas contains methane (60-80%) with smaller amount of other gaseous alkanes such as ethane, propane and butane together with some carbon dioxide and nitrogen. These hydrocarbon resources are the main supply of a large fraction of our energy.  Nomenclature of alkane Common I.U.P.A.C IUPAC : International Union of Pure and Applied Chemistry I.U.P.A.C. Substituents Parent Chain Suffix  Nomenclature of alkane Alkanes are named according to the following rules: 1. Class suffix is ane. 2. Choose the longest chain of carbon atoms and name it. 3. Number the parent chain, staring at the end closer to substituent. 4. Identify the substituent and its positions. 5. Attach the number and name of the substituent to the name of the parent in an alphabetical order.  Nomenclature of alkane If more than one different chain are of equal length (number of carbons), choose the one with the greater number of branches (substituents) as the parent 1 2 3 4 5  Substituents Identify and number the substituents and list them in alphabetical order  Physical properties of alkane Alkanes are non polar compounds. Because, the attractive forces between molecules are weak. The first four members are gases at room temperature, while the C5 to C17 alkanes are liquids. Soluble in non-polar compounds & Insoluble in water. Alkanes are colorless and odorless by nature. The intermolecular Vander Waal force attracts alkane molecules. Alkanes with stronger intermolecular van der Waals forces have higher boiling points. The melting point of alkanes follow the same trend as their boiling point that is, it increases with increase in molecular weight. Alkanes and cycloalkanes are chemically unreactive compared to other organic compounds with functional groups. Alkanes and cycloalkanes, generally don't undergo reaction with strong acids, bases, reducing agents or oxidizing agents. Because of their lack of reactivity. So alkanes are called paraffins.  Importance of alkanes in Dentistry: Anesthetics: Some alkanes, like halothane, have been used as inhalation anesthetics in dental procedures. Solvents: Alkanes serve as solvents for various dental materials. Impression Materials: Hydrocarbon-based impression materials (such as silicone- based compounds) are widely used in dentistry. Waxes: Dental waxes, used for modeling and casting, often contain alkanes. Lubricants: Alkanes find applications as lubricants for dental instruments and equipment.  Cycloalkanes Cycloalkanes are alkanes in which the carbon atoms are arranged in a ring. General molecular Formula ----> CnH2n n = no. of carbon atoms Just by forming a ring, the number of hydrogens decreases by two The simplest cycloalkane is cyclopropane.  Nomenclature of cycloalkane 1  Nomenclature of cycloalkane Cycloalkanes are named according to the number of carbon atoms in the ring with the prefix cyclo-added. If C ring = or > C substituent, it is named as an alkyl-substituted cycloalkane If C ring < C substituent, it is named as an cycloalkyl-substituted alkane.  When more than one substituent is present, the ring is numbered beginning with one substituent in the way that gives the next substituent the lowest possible number.  Uses of cycloalkanes 1. In the pharmaceutical industry, they are employed as organic solvents. 2. Cancer patients are treated with carboplatin, a drug synthesized from cyclobutane. 3. Used as perfumes in the perfume industry and as pigments. 4. Cyclopropane is employed as an anesthetic agent in the field of medicine. 5. It is also utilized in petroleum industries