Organic Chemistry

Introduction Organic chemistry is the study of carbon compounds (generally hydrocarbons). Animals, plants, and other forms of life consist of organic compounds. Nucleic acids, proteins, fats, carbohydrates, enzymes, vitamins, and hormones are all organic compounds. Biochemistry was developed later as the study of the chemical compounds and reactions in living cells. Intro

Organic Chemistry - Introduction Scientists had originally thought that organic compounds contained a “vital force” due to their natural origin like milk obtained from animals, sugar from sugar cane are organic. This was disproved by Friedrich Wöhler in 1828. Wöhler was able to make urea, a carbon compound in human urine, in the laboratory from a mineral. Organic chemistry is an enormous field. Intro

Numbers and Types of Bonds Application of the octet rule indicates that these elements should bond as shown below: Section 14.1

Identifying Valid & Incorrect Structural Formulas Example Two structural formulas are shown above. Which on does not represent a real compound? In structure (a) each H and halogen has one bond, each C has four bonds, and each O has two bonds. This is a valid structure. Section 14.1

Identifying Valid & Incorrect Structural Formulas An Example As we examine (b), we note that each H has one bond, each C has four bonds, the N has three bonds, BUT the O has three bonds. The O should only have two bonds. Therefore (b) is not a valid structure. Section 14.1

Hydrocarbons Hydrocarbons are the most simple organic compounds. Hydrocarbons contain only carbon (C) and hydrogen. (H) For classification purposes, all other organic compounds are considered derivatives of hydrocarbons. Hydrocarbons can be divided into aromatic and aliphatic hydrocarbons. Section 14.2

Aromatic Hydrocarbons Aromatic hydrocarbons contain one or more benzene ring. Benzene (C6H6) is the most important aromatic hydrocarbon. It is a clear, colorless liquid with a distinct odor. Section 14.2

Other Aromatic Hydrocarbons Toluene is used in modeling glue. Naphthalene is use in mothballs, and Phenanthrene are used in the synthesis of dyes, explosives, and drugs. Section 14.2

Aliphatic Hydrocarbons Aliphatic hydrocarbons are hydrocarbons having no benzene rings. Aliphatic hydrocarbons can be divided into four major divisions: Alkanes Cycloalkanes Alkenes Alkynes Section 14.3

Classification of Hydrocarbons Section 14.2

Alkanes Alkanes are hydrocarbons that contain only single bonds. Alkanes are said to be saturated hydrocarbons Because their hydrogen content is at a maximum. Alkane general formula  CnH2n + 2 The names of alkanes all end in “-ane.” Methane  butane are gases Pentane  C17H36 are liquids C18H38 and higher are solids Section 14.3

Members of the Alkane Series All satisfy the general formula CnH2n + 2 Section 14.3

Models of Three Alkanes Names, Structural Formulas, Condensed Structural Formulas, and Ball-and-Stick Models Section 14.3

Methane – Tetrahedral Geometry Ball-and-Stick & Space-Filling Models Carbon’s four single bonds form angles of 109.5o Section 14.3

Alkane Products Alkanes are also found in paints, plastics, drugs, detergents, insecticides, and cosmetics. Only 6% of the petroleum consumed goes into making these products. The remaining 94% of the petroleum is burned as one of the various energy-related products. Although alkanes are highly combustible, they are otherwise not very reactive.. Section 14.3

Alkyl Group This group does not exist independently but occurs bonded to another atom or molecule. Section 14.3

Organic Compound Nomenclature Due to the large number, variety, and complexity of organic compounds, a consistent method of nomenclature has been developed. Section 14.3

IUPAC System of Nomenclature Alkanes Compound is named as a derivative of the longest continuous chain of C atoms. Positions & names of the substituents added If necessary, substituents named alphabetically More than one of same type substituent – di, tri, tetra The C atoms on the main chain are numbered by counting from the end of the chain nearest the substituents. Each substituent must have a number. Section 14.3

The longest continuous chain of C atoms is five Example The longest continuous chain of C atoms is five Therefore this compound is a pentane derivative with an attached methyl group Start numbering from end nearest the substituent The methyl group is in the #2 position The compound’s name is 2-methylpentane. Section 14.3

Substituents in Organic Compounds Section 14.3

Drawing a Structure from a Name Number the C atoms from right to left. Attach a methyl group (CH3--) to carbon number 2 and number 3. Add necessary H atoms. 2,3-dimethylhexane Section 14.3

Cycloalkanes Members of the cycloalkane group possess rings of carbon atoms. They have the general formula CnH2n. Each carbon atom is bonded to a total of four carbon or hydrogen atoms. The smallest possible ring consists of cyclopropane, C3H6. Section 14.3

The First Four Cycloalkanes Note that in the condensed structural formulas, there is a carbon atom at each corner and enough hydrogens are assumed to be attached to give a total of four single bonds. Section 14.3

Alkenes Members of the alkene group have a double bond between two carbon atoms. One hydrogen atom has been removed from two adjacent carbon atoms, thereby allowing the two adjacent carbon atoms to form a double bond. General formula is CnH2n Begins with ethene (ethylene) C2H4 Section 14.3

Some Members of the Alkene Series Section 14.3

Naming Alkenes “-ane” suffix for the corresponding alkane is changed to “-ene” for alkenes. A number preceding the name indicates the C atom on which the double bond starts. The carbons are numbered such that the double bond has the lowest number. For example, 1-butene and 2-butene Section 14.3

Alkynes Members of the alkyne group have a triple bond between two carbon atoms. General formula is CnH2n-2 Begins with ethyne (acetylene) C2H2 Due to the triple carbon bond, each alkyne molecule can react with two molecules of hydrogen. Section 14.3

Alkenes are very Reactive and are termed “unsaturated hydrocarbons” Alkenes will characteristically react with hydrogen to form the corresponding alkane. Section 14.3

Alkynes are Unsaturated Hydrocarbons Due to the triple carbon bond, each alkyne molecule can react with two molecules of hydrogen. Section 14.3

Groups with a Carbon–Oxygen Double Bond (Carbonyl Groups) Aldehyde: one hydrogen bonded to C=O Ketone: two C’s bonded to the C=O Carboxylic acid: OH bonded to the C=O Ester: C-O bonded to the C=O Amide: C-N bonded to the C=O Acid chloride: Cl bonded to the C=O

Alcohols Alcohols are organic compounds containing the hydroxyl group, —OH, attached to an alkyl group. General formula is R—OH Their IUPAC (International Union of Pure and Applied Chemistry) names end in “-ol.” The most simple alcohol is methanol. Ethanol is used in alcoholic beverages, perfumes, dyes, and varnishes. Section 14.4

Amines Organic compounds that contain nitrogen and are basic (alkaline) are called amines. General formula for an amine is R—NH2. Section 14.4

Carboxylic Acids Carboxylic acids contain the carboxyl group . (–COOH) They have the general formula RCOOH. Section 14.4

Isomers Compounds having same chemical formula but different structures are called isomers. There are two classes of isomers 1. Constitutional or Structural Isomerism Stereo Isomerism.

Chain Isomerism Compounds having same molecular formula but different carbon chain or skeleton are called chain isomers and this phenomenon is called Chain isomerism. Molecular Formula C5H12 Molecular Formula C4H10O

Functional group Isomers Compounds having same molecular formula but different functional groups are called functional groups isomers.

Position isomerism Compounds having same molecular formula but different position of Functional group or double bond or triple bond are called position isomers and this phenomenon is called Position isomerism.

Optical Isomerism The compounds having the same molecular formulas, structural formulas, physical and chemical properties but differing in their action on plane polarized light are called optical isomer and phenomenon is called optical isomerism. Optical activity The property of a compound to rotate the plane polarized light in either direction is called optical activity. OR The substance rotating the plane of polarized light to the left or right is called optical active and this property of rotating planner polarized light is called optical activity.

Dextro rotatory ( or d form) Laevo Rotatory (or l form) The molecule rotating the plane of polarized light to the left is called Laevo rotatory or l form. Dextro rotatory ( or d form) The molecule rotating the plane of polarized light to the right is called dextro rotatory or d form.

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