organic chemistry

all E+ are Lewis acids but

Not all LA are E+

we can expand acid and base more into

Nucleophiles + Electrophiles

non carbons, hetero atoms: ether

R represents any alkyl group (CH Combo)

chemical kinetics

Rate of change in substances; change in concentration

All Nu- are Lewis bases and

All LB are Nu-

aromatic hydrocarbons

Alternating double and single bonds in a ring

Which of these elements is SOMETIMES found in an organic molecule? (select all that apply)

Bio systems: N, O, S, P Lab Systems: F, Cl, Br, I

The full delocalization of electrons by resonance is better described by __________________ and ____________________

Molecular Orbital (MO) theory not hybridization

pi bonds (valance bond theory)

- has electron density above/below or in front/behind the sigma bond which prevents overlap between electrons in different bonds. -require side to side overlap -double or triple bond - weaker than sigma

how can estimate relative acid strengths by looking at structure induction

- help from EN neighbors by long range EN e- donation/ withdrawng through multiple sigma bonds. - EN neighbors gives better acids through proximity, amount of EN neighbors present, and through the highest EN

how can estimate relative acid strengths by looking at structure electronegativity?

- more EN atom (right side of periodic table) better acid i.e CH4 < NH3 < H2O < HF NOTE: because CH4 is a terrible acid we consider it not to be one. sp3 are terrible acids

how can estimate relative acid strengths by looking at structure hybridization

- of atom w/ H+ attached - in s orb e- can go to nucleus (stabilize e-) - in the p orbital we have node at nucleus, e- cannot approach

Resonance hybrids typically show

- partial charges, with the formal charge of spread out over several atoms # of valence e- in neutral atom - (# e- in lone pairs + ½ x # e- in bonds) - partial bonds where the bond order between the atoms the number of electron pairs shared divided by the number of connections (bonds) they're shared over. Bond order = number of electrons shared/ Number of atoms

We can estimate relative acid strengths by looking at structure

- size -Electronegativity -Resonance -hybridization -induction

resonance hybrid

blend of the resonance structures where electrons are spread out over multiple central atoms (delocalized)

What are the three common uses for parenthesis in condensed formula:

branches containing central atoms repetition within a chain symmetrical ends of a chain.

How can we convert between resonance structures

by moving pi bonds, lone pairs, and charges around the framework of single bonds

Which of these elements is ALWAYS in an organic molecule?

carbon and hydrogen

Chemical Thermodynamics

change in energy over a reaction process

resonance structures occurs because of

conjugation (3 or more p orbitals)

Molecular orbital theory means electrons

delocalized over entire molecule (get bonding orbitals e- between atoms) (get anti-bonding orbitals in nodes between atoms

functional groups

display predictible/ chemical + physical properties similar

Arrhenius Base

donates OH- in eater (Have OH in Formula) i.e NaOH, KOH, Ca(OH)2, Na2O, K2O, MgO, NH4OH (NH3), OH-,

Electrophiles

e- loving; want to gain electrons E+ - accepts e- - empty orb, +, s+ -H+, all Lewis acids, CCl s+, CH2=O S+, CH3+, AlCl3, Zn2+, CH3COCH3

Resonances structures only permits the movement of

electrons

Resonance structures contain

electrons that are able to move around the molecule without moving the atoms. These mobile electrons are delocalized and are not part of the basic single bonds that hold the molecule together (sigma bond network).

Chemical Thermodynamics governs

extent of reaction

Select True or False for the following statements. Atomic orbitals are the best description of electron placement in bonded atoms.

false

Select True or False for the following statements. Hybridization uses all the electrons in a molecule to build bonds.

false

True or False: An electrophile will generally have an overall negative charge.

false

True or False: Bronsted-Lowry neutralization produces a salt and water.

false

Arrhenius Acid-Base Theory contribution

great but does not work well w/ organic chemistry. Most organics are oils which dont mix well

MO theory

hybrid orbitals making up the single bonds (sigma bonds) and unhybridized p-orbitals making up any delocalized charges, lone pairs or pi bonds. The unhybridized p-orbitals can then be considered as localized (single pi bonds, VBT) or delocalized (extended pi systems, limited MO theory)

In reality, the molecule does not undergo rapid exchanges between the possible resonance structures. Instead the molecule

is a blend of the resonance structures where electrons are spread out over multiple central atoms (delocalized) rather than shared only between two atoms as in a normal bond (localized) or as a lone pair on a single atom (localized).

The number of hybrid orbitals that result from hybridization

is always exactly equal to the number of atomic orbitals used:

what happens to carbon when it hybridizes into sp3

it creates a degenerate orbital or orbitals with the same energy

Shapes of Hybrid Orbitals - 2 electron groups: sp hybridization

linear shape

Constitutional Isomers of Hexane (C6H14)

longest chain: 1. hexane one Branch: 2. 2-methylpentane 3. 3-methylpentane two Branches: 4. 2,2-dimethylbutane 5. 2,3-dimethylbutane

For some molecules not all of the resonance structures are equivalent, for these molecules we can determine which resonance structures are the most relevant (major contributor to the hybrid) by

looking at formal charges

Kinetic control gives us

most stable intermediate (may not be best product

thermodynamic control gives us

most stable product (best product)

Nucleophiles

nucleus loving- want to donate; e-/ e- rich -Nu- or Nu -donates e- - lone pair, -, s- - all Lewis acid bases + all Bronsted + Base i.e H20, HO-, CL-, H2C=O S-, CH3-, CL-, OH-, NH3, CH3COO-, Br- ,

Multiple bonds

occurs when additional pairs of electrons are shared between two atoms.

Arrhenius Acids

produces H+ in water (donates in H2O) i.e HCl, HBr, HI, H2SO4, H3PO4, HCN, HF, COOH, CH3COOH, H2S , H+,

Covalent bonds form due to ___________ of electrons between bonded atoms.

sharing

lewis acid/ base reaction creates

something where we have a new empty orbital covalent bond

alkyne

sp (triple bond)

how can we estimate relative acid strengths by looking at structure size

- (larger atom down periodic table) ie HF < HCL < HBr < HI - if same size, it has good orbital overlap and therefore is harder to break - if different size, it had poor orbital overlap and therefore is easier to break

Bronsted-Lowey base

- Accepts H+ i.e HO-, CH3-, H2O, NH3, CH3Oh, CH3NH2, Cl-, CN-, SH-, CH3COO-, CH30CH3, lone pair, or - -stronger base accepts H+, weaker is forced to lose it -stronger base = weaker conj acid

Bronsted-Lowey Acid

- Donates H+ i.e all Arrhenius Acids (HCl, HBr, HI, H2SO4, H3PO4, HCN, HF, COOH, CH3COOH, H2S )+ H2O, NH3Ch3Oh, CH3Nh2, C-Triple-CH, C-double-CH2, CH3CH2NH2. H+, CH3+ -stronger acid = weaker conj base

Arrhenius vs. Bronsted-Lowry: Arrhenius

- acid base in H20 -measures [H30+] as pH - 0-14 range -pH = -log[H30+]

Molecular orbital theory is used for

- delocalized systems (Resonance Structures) i.e two pi bonds, pi+lone pair, pi+ -, pi + empty orbitals

lewis base

- donates a pair of e- into empty orbitals -all Bronsted- Lowry bases + alkanes - CH3- , CL-, OH-, NH3, CH3COO-, H2O,

Molecular orbital theory

- states we need to overlap all atomic orbitals to create a equal number of molecular orbitals - means electrons are dmeans electrons ____________(get bonding orbitals e- between atoms) ____________(get antibonding orbitals in nodes between atoms

valence bond theory

- talks about overlap of valence orbitals to create bonds - able to take a look at things localized on a single central atom

how can estimate relative acid strengths by looking at structure Resonance

- the more we can spread out charge easier it is to carry

Prioritizing Resonance Structures:

-Atoms in organic molecules generally prefer octets and resonance structures with full octets are generally most significant. - All atoms should have minimal (ideally 0) formal charge -If formal charges are necessary:

Arrhenius vs. Bronsted-Lowry: Bronsted-Lowry

-acid/base in any solution or mixture - pka= -log ka -measures pH were 50% dissociation - has -10-50 range -pka weaker acid is greater than pka stronger acid

sigma bonds (Valence bond theory)

-type of valence bond theory bond - has electron density directly between the two nucleii that are single bonds - end to end overlap - rotate freely -stronger than pi

An sp3 orbital is made up of the average of__________ orbital and __________ orbitals. There are ________ sp3 orbitals around CH4.

1 s and 3 p 4

Molecules with Functional Groups:

1) Use the method for alkane's to determine the number of possible carbon backbones. 2) Fill in the functional group in all the possible places on each backbone.

4 scenarios we have conjugation (resonance)

1. empty p orbital (plus sign next to double bond) 2. lone pairs (two dots next to double bond) 3. two pi bonds (two double bonds not close together. 4. Radical (dot next to double bond)

Atoms with two pi bonds will be

sp hybridized with two un-hybridized p-orbitals producing a linear molecule with 180° bond angles and two pi bonds, one above and below and one in front and behind the sigma bond. 2 σ bonds, 2 π bond sp hybridization bond angles = 180

Alkenes (hydrocaron)

sp2 (double bonds)

resonance structures.

When Lewis structures vary only in the positions of the electrons they are in

intermediate

a high energy substance that exists for a short time in the process of reaction

catalyst

a substance that changes the mechanism, but is not itself changed by the reaction

Kinetic control

about rates; fastest, easiest path

thermodynamic control

about the change in enthalpy; change in energy (released) delta H= bonds broken - bonds formed Delta Sigma= delta T- T Delta S

Lewis acid

accepts electron pairs into a empty orbital i.e H+, CH3, CH3+/ carbocations BH3 , BF3 , AlCl3 , AlBr3 Zn2+, Fe3+ Note: HCl is not a Lewis acid it just process H+ which is a Lewis acid

we can affect reaction speed by

adding heat increasing concentration changing mechanism w/ catalyst

Lewis acid-base reaction come together to form

adduct which is also a covalent bond

The hybrid is the average of

all the resonance structures with greater weight going to the more significant structures.

exothermic

you selected a reaction that has a negative enthalpy

Atoms with a single pi bond must be

sp2 with an unhybridized p-orbital available to form the pi bond, producing a trigonal planar molecules with 120° bond angles and a pi bond above and below the plane of the atoms. 3 σ bonds, 1 π bond sp2 hybridization bond angles = 120

alkanes (hydrocaron)

sp3 (single Bonds)

In organic molecules atoms with all sigma bonds/lone pairs will be

sp3 hybridized with approximately 109.5° bond angles and tetrahedral electron pair geometry i.e 4 σ bonds sp3 hybridization bond angles = 109.5o

chemical kinetics governs

speed of reactions: ie Activation energy Rate Determining Step

Orbitals

tells you the probability of finding an electron somewhere within an atom. keep in mind electrons behave as particals or as waves

Shapes of Hybrid Orbitals -4 electron groups: sp3 hybridization

tetrahedral

Energetically the total energy of the hybrid orbitals is the same as the total energy of the atomic orbitals, but

the energy of the individual orbitals is different, thus the different shape and standing wave

rate determining step

the highest energy point of the reaction

activation energy

the highest point of energy for a step of a mechanism

transition state

the point where bonds break or form

A wedge in a structure means the bond is pointed

towards viewer

Ionic bonds form due to _________ of electrons between bonded atoms.

transfer

Shapes of Hybrid Orbitals - 3 electron groups: sp2 hybridization

trigonal planar

Select True or False for the following statements. Carbon as a plain atom has two unpaired electrons in p orbitals.

true

Select True or False for the following statements. Molecular orbital theory delocalizes electrons over the whole molecule.

true

True or False: A strong conjugate acid will have a weak conjugate base.

true

True or False: All Lewis bases are also nucleophiles and Bronsted-Lowry bases.

true

True or False: Bronsted-Lowry acids can occur in any solvent.

true

True or False: Bronsted-Lowry acids include all Arrhenius acids.

true

True or False: H bonded to larger atoms are more acidic due to poor orbital overlap, and polarizability of large orbitals.

true

True or False: Increasing the % of s-orbital in a hybrid orbital makes the H bonded more acidic.

true

True or False: Induction is long range electronegativity, and the presence of electronegative atoms improves acidity of distant H.

true

True or False: Many polar bonds are electrophiles at one end and nucleophiles at the other.

true

True or False: Nucleophiles are sometimes abbreviated as Nu-, while electrophiles are sometimes abbreviated as E+.

true

True or False: The strength of an acid depends primarily on the conjugate base's ability to support a negative charge.

true