New version page

UMass Amherst CHEM 261 - Alkanes, Functional Groups, Naming Branched Alkanes

This preview shows page 1 out of 4 pages.

View Full Document
View Full Document

End of preview. Want to read all 4 pages?

Upload your study docs or become a GradeBuddy member to access this document.

View Full Document
Unformatted text preview:

CHEM 261 1st Edition Lecture 7Outline of Last Lecture:I. Using pKa to determine equilibriaII. Lewis Acids and BasesIII. Non-covalent InteractionsIV. AlkanesV. Functional GroupsVI. Alkyl GroupsOutline of Current Lecture:I. Alkanes and Functional Groups RecapII. IsomersIII. Naming Branched AlkanesIV. Viewing/Drawing Conformations of EthaneAlkanes and Functional Groups Recap:Functional Group: group of specific atoms or bonds within molecules. Functional groups have similar reactivities and undergo similar reactions. Relative reactivity can be affected by neighboring atoms or groups. Moiety: functional group or components of a functional group** can focus on moiety of functional group or moiety of a component of functional group (one atom’s moiety)Alkane Characteristics:C-C ; sigma bond-Composed of C, H-All carbons are saturated (4 bonds on each carbon)-Formula: CNH2N+2 (for noncyclic alkanes)Alkanes can be molecules by themselves, and can also be components of other molecules as alkyl groupsThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.-Carbon is classified by its connectionsClass Example: ** if connectivity is equal, then it is the same molecule. If breaking connectivity, they are not equal (isomers)Isomers:Constitutional Isomers: Isomers with the same molecular formula but have different connectivities. You must make or break a bond to get them to have the same connectivity. **When the number of carbons is greater or equal to 4 in a molecule, there is a greater chance that that molecule will have isomersNaming Branched Alkanes:-Alkanes can be linear or branchedSubstituent: branches off of parent carbon chainFormula for naming alkanes:Locant (where are the substituents/functional groups?) Prefix (what are the substituents?)  Parent (how many carbons?) Suffix (what is the primary functional group?)Step 1: Find the parent hydrocarbon (longest continuous chain of carbon atoms. If two chains exist that are of equal length, the parent chain is the one with the larger number of branch points. You may have to “turn corners” to find the parent chain; it may not be apparent)Step 2: Number the atoms in the longest chain (Beginning at the end nearest to the first branch point, number each carbon atom in the parent chain. If there is branching an equal distance away from both ends of the parent chain, begin numbering at the end nearer to the second branch point)Step 3: Identify and number the substituents (Assign a number to the substituent according to which carbon it is attached to on the parent chain)Step 4: Write the name as a single word (ex. 2, 4, dimethyl hexane)Two Important Common Names to Know:Viewing/Drawing Conformations of Ethane:Sigma bonds rotation of molecule, causes the substituents to rotate past one another, either getting closer together or farther away from each otherNewman projection: Staggered= less energy (hydrogens are farther away from each other)Eclipsed= More energy (hydrogens are closer to each


View Full Document
Loading Unlocking...
Login

Join to view Alkanes, Functional Groups, Naming Branched Alkanes and access 3M+ class-specific study document.

or
We will never post anything without your permission.
Don't have an account?
Sign Up

Join to view Alkanes, Functional Groups, Naming Branched Alkanes and access 3M+ class-specific study document.

or

By creating an account you agree to our Privacy Policy and Terms Of Use

Already a member?