Chapter 25 Organic and Biological Chemistry

Chemistry, The Central Science, 10th edition Theodore L. Brown; H. Eugene LeMay, Jr.; and Bruce E. Bursten Chapter 25Organic and Biological Chemistry John D. Bookstaver St. Charles Community College St. Peters, MO  2006, Prentice Hall, Inc.

Bell work • Grab a whiteboard, marker, and eraser. You’ll need it soon. • In your notebook, write the ten prefixes for organic compounds.

Agenda • Bell work • Organic nomenclature overview • Organic practice • Pass out lab books • Begin review of chapter 4 • Homework: • Pre lab questions (due Tuesday), read through lab so you’re prepared for Tuesday • Homework problems (on sheet) due Thursday

Organic Chemistry • The chemistry of carbon compounds. • Carbon has the ability to form long chains. • Without this property, large biomolecules such as proteins, lipids, carbohydrates, and nucleic acids could not form.

Structure of Carbon Compounds • There are three hybridization states and geometries found in organic compounds: • sp3Tetrahedral • sp2 Trigonal planar • sp Linear

Hydrocarbons • Four basic types: • Alkanes • Alkenes • Alkynes • Aromatic hydrocarbons

Alkanes • Only single bonds. • Saturated hydrocarbons. • “Saturated” with hydrogens.

Formulas • Lewis structures of alkanes look like this. • Also called structural formulas. • Often not convenient, though…

Formulas …so more often condensed formulas are used.

Properties of Alkanes • Only van der Waals force: London force. • Boiling point increases with length of chain.

Structure of Alkanes • Carbons in alkanes sp3 hybrids. • Tetrahedral geometry. • 109.5° bond angles.

Cycloalkanes • Carbon can also form ringed structures. • Five- and six-membered rings are most stable. • Can take on conformation in which angles are very close to tetrahedral angle. • Smaller rings are quite strained.

Alkenes • Contain at least one carbon–carbon double bond. • Unsaturated. • Have fewer than maximum number of hydrogens.

Alkynes • Contain at least one carbon–carbon triple bond. • Carbons in triple bond sp-hybridized and have linear geometry. • Also unsaturated.

Nomenclature of Alkynes 4-methyl-2-pentyne • Analogous to naming of alkenes. • Suffix is -yne rather than –ene.

Aromatic Hydrocarbons • Cyclic hydrocarbons. • p-Orbital on each atom. • Molecule is planar. • Odd number of electron pairs in -system.

Aromatic Nomenclature Many aromatic hydrocarbons are known by their common names.

Functional Groups Term used to refer to parts of organic molecules where reactions tend to occur.

Alcohols • Contain one or more hydroxyl groups, —OH • Named from parent hydrocarbon; suffix changed to -ol and number designates carbon to which hydroxyl is attached.

Ethers • Tend to be quite unreactive. • Therefore, they are good polar solvents.

Carbonyl Compounds • Contain C—O double bond. • Include many classes of compounds.

Aldehydes At least one hydrogen attached to carbonyl carbon.

Ketones Two carbons bonded to carbonyl carbon.

Carboxylic Acids • Have hydroxyl group bonded to carbonyl group. • Tart tasting. • Carboxylic acids are weak acids. CH3COOH

Carboxylic Acids

Esters • Products of reaction between carboxylic acids and alcohols. • Found in many fruits and perfumes.

Amides Formed by reaction of carboxylic acids with amines.

Amines • Organic bases. • Generally have strong, unpleasant odors.

Organic Nomenclature • Three parts to a compound name: • Base: Tells how many carbons are in the longest continuous chain.

Organic Nomenclature • Three parts to a compound name: • Base: Tells how many carbons are in the longest continuous chain. • Suffix: Tells what type of compound it is.

Organic Nomenclature • Three parts to a compound name: • Base: Tells how many carbons are in the longest continuous chain. • Suffix: Tells what type of compound it is. • Prefix: Tells what groups are attached to chain.

Organic Nomenclature • 2, 3-dimethylpentane • How many carbons are in the main chain? • What do the numbers mean?

Organic Nomenclature • How many bonds can carbon form? • How can you tell how many bonds an atom can form?

To Name a Compound… • Find the longest chain in the molecule. That’s your base • Number the chain from the end nearest the first substituent encountered. • List the substituents as a prefix along with the number(s) of the carbon(s) to which they are attached.

To Name a Compound… If there is more than one type of substituent in the molecule, list them alphabetically.

Sample problems • Going from condensed formula to structural formula • When there are parenthesis, it means that it comes off that specific carbon. It is not a part of the main chain. • Follow nomenclature guidelines

Pass out lab books • In pen, write your name in the front of the book • Do not write in these books otherwise. You will be able to copy tables into your actual lab notebooks. You’ll get these on Tuesday. • Read through lab 1 well enough so you have a solid idea of what you’re going to be doing on Tuesday. Tuesday should not be the first time you read through the lab. • Complete the pre-lab questions. They’re due on Tuesday.

Bell work 9/6 • Turn your pre-lab questions into the tray. • What are some questions you have about the lab? • When you are finished, put your science notebook back. Grab and read a “Techniques for Handling Crucible” hand out.

Agenda • Bell work • Turn in pre-lab questions • Pass out lab notebooks • Overview use of lab notebooks • Lab edits • Homework: • Complete first 5 organic questions (due Thursday) • Work on post-lab questions and analysis (due Tuesday)

Lab notebook • Write your first and last name clearly on the front • BEWARE – these are carbon copy sheets, so use the periodic table pull out to keep from marking on several sheets at once • On the first page, create a table of contents • Skip to page 6 and fill in spaces for name, experiment, date, etc • Refer to my college lab notebooks

Lab edits • You are not going to repeat the experiment. Instead, we are going to pool data. • You would do 3 trials—instead do the lab once and then get data from two other groups • DO NOT WRITE IN THE PINK LAB BOOK • Copy the data table into your fancy lab notebook • Follow the directions outlined in your pink book. Record your actions and observations in your lab notebook.

Lab • Your lab analysis and post-lab questions will be due next week Tuesday. • Make sure you get the data from two other groups, so you can do the full analysis of Trial 1, Trial 2, and Trial 3

Chapter 4 • Aqueous reactions and solution stoichiometry

Solutions: • Homogeneous mixtures of two or more pure substances. • The solvent is present in greatest abundance. • All other substances are solutes. • Solutions in which water is the dissolving medium are called aqueous solutions

Dissociation • When an ionic substance dissolves in water, the solvent pulls the individual ions from the crystal and solvates them. • This process is called dissociation.

Ionic Compounds in Water • Ionic solid dissociates into its component ions as it dissolves • Water is an effective solvent • Oxygen is electron-rich and carries partial negative charge • Hydrogen has a partial positive charge • Polar molecule: uneven distribution of electron density

Imagine preparing two aqueous solutions—one by dissolving a teaspoon of table salt (sodium chloride) in a cup of water and the other by dissolving a teaspoon of table sugar (sucrose) in a cup of water. • How can you tell them apart?

Electrolytic Properties • Water itself is a poor conductor of electricity • Dissociated ions carry electrical charge • Electrolyte: a substance whose aqueous solution contains ions • Ex: NaCl • Nonelectrolyte: a substance that does not form ions in solution • Ex: C12H22O11 (sucrose)

Chapter 25 Organic and Biological Chemistry