Organic Chemistry Test 1

Organic Chemistry

The study of the chemical and physical properties of carbon

Anion

An ion with a negative charge

Cation

An ion with a positive charge

Up and Right

Electronegativity trend

Ionic

>1.9 Electronegativity Difference

Covalent

<1.9 Electronegativity Difference

• Two nonmetals

Nonpolar covalent

<0.5 Electronegativity Difference

Polar Covalent

0.5-1.9 Electronegativity Difference

Formal Charge

Valence Electrons - (lone pairs + Bonds)

3 - 120

Trigonal Planar - 0 Lone Pairs

Bent - 1 lone pair

Tetrahedral

• 109.5

• 0 Lone Pairs

Trigonal Pyramidal

• 107

• 1 lone Pair

• Tetrahedral

Bent

• 104.5

• 2 Lone Pairs

• Tetrahedral

Resonance Hybrid

A molecule that is best described as a composite of a number of contributing structures

Double-headed arrow

A symbol used to connect contributing structures

Resonance Structures

Representation of a molecular or ion that differ only in the distribution of valence electrons

Curved arrow

A symbol used to show the redistribution of valence electrons

Rules for Resonance

1. Same number of valence electrons

2. Obeys covalent bonding rules

3. Positions of nuclei are the same

4. Same number of paired and unpaired electrons

Functional Group

Group that shows the same physical or chemical characteristics

• Hydroxyl

• Amino

• Carbonyl

• Carboxyl

• Carboxylate

• Carbamide

• Sulfhydryl

Alcohols

• -OH (hydroxyl) is bonded to a tetrahedral carbon

• Primary, secondary, tertiary depending on how many carbons the Carbon bonded to the -OH has

Amines

• Nitrogen bonded to 1-3 Carbons

• Primary, secondary, or tertiary depending on how many carbons the nitrogen is bonded to

Aldehydes

• C=O (carbonyl group)

• Bonded to hydrogen

Ketones

• C=O (carbonyl group)

• Bonded to 2 Carbons

Carboxylic Acids

• -COOH (Carbonyl and hydroxyl)

Ester

• The -OH replaced with -OR group

Amide

• An -NH2, -NHR, or -NR2 group is bonded to the carbonyl group

Arrhenius Acid

Substance that dissolves in the water to produce H+ ions

Arrhenius Base

Substance that dissolves in water to produce OH- ions

Arrhenius

• Made by Svante Arrhenius

• Debunked because H+ ions do not exist in water because it reacts immediately with an H2O to create hydronium (H3O+)

• Definitions are valid when speaking of aqueous solutions

Bronsted-Lowery Acid

A proton donor

Bronsted-Lowery Base

A proton acceptor

Conjugate Base

The species formed when an acid donates a proton

Conjugate Acid

The species formed when a base accepts a proton

Acid/Bases Points

1. An acid can be positive, neutral, or negatively charged

2. A base can be negatively or neutrally charged (cannot be positive)

3. Acids are monoprotic, diprotic, or triprotic depending on the number of protons they give up

4. Several molecules and ions appear in both the acid and conjugate base columns; that is, each can function as either an acid or a base

5. There is an inverse relationship between the strength of an acid and the strength of its conjugate base

• The stronger the acid, the weaker its base

Strong Acid/Base

An acid/base that is completely ionized in aqueous solution

• MOST organic acids/bases are weak

Weak Acids/Bases

Only partially ionizes in aqueous solution

High pKa

• Strong bases

• Weak acids

Low pKa

• Weak bases

• Strong acids

Equilibrium Reaction

• Strong acids are harder to produce, weak acids are easier

• Far to the right if it’s easier to create the products

• Far to the left if it’s easier to create the reactants

Acidity effect

• The more electronegative the atom, the better it is at sustaining the negative charge

• Anion is stable the more acidic it is (stronger acid)

Resonance Effect

The more stable the ion (electronegative), the farther the position of equilibrium is shifted toward the right and the more acidic the compound

Inductive Effect

The polarization of electron density transmitted through covalent bonds caused by a nearby atm of higher electronegativity

• If CF3 is partially positive, that delocalizes the negative charge on the other group it’s attached to

Larger

The ___ the atom bearing the negative charge, the better it is at sustaining the charge

• Anions are always larger than the atoms from which they are derived

Lewis Acid

Any molecular or ion that can form a new covalent bond by accepting a pair of electrons

Lewis Base

Any molecular or ion that can form a new covalent bond by donating a pair of electrons

Oxonium Ion

An ion that contains an oxygen atom bonded to 3 other atoms or a group of atoms and bears a positive charge

Hydrocarbon

A compound that contains only carbon atoms and hydrogen atoms

Saturated hydrocarbons

A hydrocarbon containing only carbon-carbon single bonds

Ethane

C-C single bond

Ethene

C=C double bond

Ethyne

C≡C triple bond

Benzene

1 or more benzene like rings

Unsaturated Hydrocarbons

Hydrocarbon containing at least one carbon-carbon pi bond (double or triple)

Meth-

1 Carbon

Eth-

2 Carbon

Prop-

3 Carbons

But-

4 Carbons

Pent-

5 Carbons

Hex-

6 Carbons

Hept-

7 Carbons

Oct-

8 Carbons

Non-

9 Carbons

Dec-

10 Carbons

Constitutional Isomers

Compounds of the same molecular formula, but a different order of attachment of the atoms

IUPAC Naming

• Parent Name

- Indicates Longest Chain

- Alkane Group

• Substitute

- Alkyl Group

- Number to indicate where it is

Alkyl Group

Group derived by removing a hydrogen from an alkane; given the symbol R

R

Symbol used to represent the alkyl group

Common Names

Simply based on the number of carbons

• Iso- added to indicate branches

Carbon Classification

Primary, secondary, Tertiary, and quaternary depending on how many carbons are bonded to it

Hydrogen Classification

Based on what type of Carbon is bonded to it (1, 2, 3, 4)

Cycloalkanes

Saturated hydrocarbons that contain carbon atoms joined to form a ring

• Contains 2 fewer H than the other alkane with same number of carbons

IUPAC Parts of Speech

1. Prefix

• Shows the number of Carbon atoms in parent chain

2. Infix

• Shows the nature of the carbon-carbon bonds in the parent chain

3. Suffix

• Shows the class of compounds to which the substance belongs

Infix All Single bonds

-an-

Infix Double bonds

-en-

Infix Triple Bonds

-yn-

Suffix Hydrocarbon

-e

Suffix alcohol

-ol

Suffix aldehyde

-al

Suffix ketone

-one

Suffix Carboxylic Acid

-oic acid

Conformation

Any 3-D arrangement of atoms in a molecular that results by a rotation about a single bond

Staggered Conformation

Conformation about C-C single bond where atoms on one C are as far apart as possible from the atoms in the adjacent carbon

Newman’s projection

A way to view a molecule by looking along a C-C bond

1. Select a C-C bond you wish to look down at

2. Draw in the hydrogens

3. Decide which view to view the bond from

Eclipsed Conformation

Conformation about a single C-C bond where one carbon’s atoms are as close as possible to adjacent carbons

Torsional Strain

Strain the happens when atoms separated by 3 bonds are forced from staggered to eclipse conformation

• AKA eclipse interaction strain

Angle Strain

The strain that arises when a bond angle is either compressed or expanded compared with its optimal value

Chair conformation

Most stable puckered conformation of a cyclohexane ring

• 109.5

Puckered

Bent, not planar, relieves torsional strain

Axial Bond

• On Chair Conformation

• Up or down

Equational Bond

• On Chair Conformation

• Side to side or diagonal

Steric Strain

Strain when atoms separated by 4 or more bonds are forced abnormally close

• AKA nonbonded interaction strain

Boat Conformation

A puckered conformation of a cyclohexane ring in which carbons 1 and 4 of the rings are bent toward each other

Interconversion of Chair

All C-H bond that are equational are axial now and vice versa

Diaxial Interactions

Interactions between groups in parallel axial positions on the same side of the chair of a cyclohexane ring

Cis-Trans Isomers

Isomers that have the same order or attachment of their atoms, but different arrangement of their atoms in space, due to presence of a ring of carbon of C=C double bond

Trans

Across From

Cis

On the same side

Alkane Density at 0

• 1-4 Carbons are gases at room temperature

• 5-17 Carbons are colorless liquid

• 18+ Carbons are white waxy solids

MP and Dispersion

• Melting point of alkanes increases with molecular weight

• Constitutional Isomers are different

• Only forces between alkanes are dispersion