Intro to Organic Chemistry

Organic Chemistry - Introduction Organic chemistry is the study of carbon compounds. 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

Hydrocarbons Simplest organic compound Contain only carbon and hydrogen Hydrocarbons can be divided into aromatic and aliphatic hydrocarbons.

Classification of Hydrocarbons Copyright © Houghton Mifflin Company. All rights reserved. Section 14.2

Aromatic Hydrocarbons Contain one or more benzene (C6H6) rings Benzene is a widely used colorless liquid with a distinct odor, and is a carcinogen 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. Copyright © Houghton Mifflin Company. All rights reserved. Section 14.2

When Other Atoms are Substituted for the H’s in the Benzene Ring A vast array of other compounds can be produced Copyright © Houghton Mifflin Company. All rights reserved. Section 14.2

Aliphatic Hydrocarbons Aliphatic hydrocarbons have no benzene rings. Divided into four major divisions: Alkanes Cycloalkanes – ring shaped Alkenes – contain at least one double bond between carbons Alkynes – contain at least one tripple bond between carbons Section 14.3

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 – CH4 Ethane – C2H6 Propane – C3H8 Butane – C4H10 Copyright © Houghton Mifflin Company. All rights reserved. Section 14.3

The First Eight Members of the Alkane Series All satisfy the general formula CnH2n + 2 Copyright © Houghton Mifflin Company. All rights reserved. Section 14.3

Visualization of an Alkane’s Structure Structural formula – a graphical representation of the way atoms are connected Condensed structural formula – save time/space and are convenient Ball-and-Stick models – 3D models that can be built by students Copyright © Houghton Mifflin Company. All rights reserved. Section 14.3

Alkyl Group Alkyl group contains one less hydrogen than the corresponding alkane. In naming this group the “-ane” is dropped and “-yl” is added. Methyl- Ethyl- Propyl- Butyl- Used as prefixes when naming structures

Alkyl Group This group does not exist independently but occurs bonded to another atom or molecule. Copyright © Houghton Mifflin Company. All rights reserved. Section 14.3

Constitutional Isomers Compounds that have the same molecular formula but different structural formulas In the case of many alkanes there is more than one way to arrange the atoms Copyright © Houghton Mifflin Company. All rights reserved. Section 14.3

Number of Possible Isomers of Alkanes Carbon Atoms can bond in many different ways

Butane Continuous-Chain or Straight-Chain Structure Structural Formula Ball-and-Stick Model Copyright © Houghton Mifflin Company. All rights reserved. Section 14.3

Isobutane (2-methylpropane) Branched-chain Structure Structural Formula Ball-and-Stick Model Copyright © Houghton Mifflin Company. All rights reserved. Section 14.3

IUPAC System of Nomenclature For Alkanes Compound is named as a derivative of the longest continuous chain of C atoms. 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. Positions & names of the substituents added If necessary, substituents named alphabetically More than one of same type substituent – di, tri, tetra Section 14.3

Naming Structures Identify and name the longest continuous chain of C. pentane Start numbering carbons from the end closest to the substituent Identify all substituents and their position The methyl group is in the #2 position The compound’s name is 2-methylpentane. Section 14.3

Substituents in Organic Compounds

Identify and name the longest chain Number carbons Propane Number carbons Identify substituents and position 2-bromo 2-methyl Arrange substituents alphabetically in front of parent name 2-bromo-2-methylpropane

Drawing Structures from Names An Example 2,3-dimethylhexane. Identify and draw the parent chain Add bonds to each carbon so that each has four bonds. Copyright © Houghton Mifflin Company. All rights reserved. Section 14.3

Drawing a Structure from a Name 2,3-dimethylhexane 3. Number the C atoms (frequently, chemists number from right to left???) 4. Attach any substituents to the appropriate carbon Methyl group (CH3-) to carbon number 2 and number 3. 5. Add necessary H atoms. Copyright © Houghton Mifflin Company. All rights reserved. Section 14.3

Drawing a Structure from a Name 2,2,4-trimethylpentane. Identify and draw the parent chain Add bonds to each carbon so that each has four bonds. Copyright © Houghton Mifflin Company. All rights reserved. Section 14.3

Drawing a Structure from a Name 2,2,4-trimethylpentane. 3. Number the C atoms 4. Attach any substituents to the appropriate carbon Methyl group (CH3-) to carbon number 2, 2 and number 4. 5. Add necessary H atoms.

Drawing a Structure from a Name 4-chloro-2,6-dimethylheptane Identify and draw the parent chain Add bonds to each carbon so that each has four bonds. Copyright © Houghton Mifflin Company. All rights reserved. Section 14.3

Drawing a Structure from a Name 4-chloro-2,6-dimethylheptane 3. Number the C atoms 4. Attach any substituents to the appropriate carbon Methyl group (CH3-) to carbon number 2 and 6 Cl- to carbon number 4 5. Add necessary H atoms. CH3 Cl CH3