ACS Organic Chemistry First Semester Final Exam Study Guide

-al

-ol or hydroxy-

-one

-oic acid

-oate

-ether or alkoxy-

Iodo- or Bromo- etc.

-amide

Amino- or -amine

Aldehyde

Alcohol

Ketone

Carboxylic acid

Ester

Ether

Alkyl halides

Amide

Amine

Constitutional Isomer

A compound with the same atoms but different atoms bonded to each other

Stereoisomers

Molecules with the same atoms differing only in 3D configuration

Enantiomers

Stereoisomers with exactly opposite stereochemical designations at all stereogenic carbons

Diasteriomers

Stereoisomers with several changes in the stereochemical designations of stereogenic carbons (not completely opposite)

R

Clockwise

S

Counterclockwise

cis

Same

trans

Different

E

Trans (in reference to alkenes)

Z

Cis (in reference to alkenes)

Ortho

1,2 substitution

Meta

1,3 substitution

Para

1,4 substitution

Protocol for naming esters

1) identify alkyl that is part of substituted alcohol and use this first

2) identify alkyl on other side of carbonyl and use this as a second word, ending in "-oate" (include carbonyl carbon)

Benzyl vs. phenyl

Benzyl: ring + CH2

Phenyl: ring

Aniline

Ring + NH2

Protocol for naming substituted amides

1) first, name the substituted group on the nitrogen

2) then, name the group on the other side of the carbonyl, ending in "-amide" (including carbonyl carbon)

What is the equation for Huckel's numbers? What are Huckel's numbers?

4n + 2

Huckel's numbers are the number of electrons in a pi system in aromatic compounds

Do lone pairs contribute to hybridization?

Yes

How do you draw a Lewis structure?

Determine the number of valence electrons for each atom and add them up

Attempt to form octets at each atom, counting bonds as two electrons

How is free energy related to acidity?

In a reaction where a proton is lost, decreasing free energy implies more stability in the products, and thus more willingness to donate a proton, meaning more acidic.

What is the Gibbs free energy equation for an acid reaction?

Delta G = -RTln([A-][H3O+]/[HA][H2O])

What are the factors influencing acidity?

MARIO minus M

A-Atom H is bonded to

R-Resonance

I-Induction

O-Orbitals

How do electron withdrawing groups influence acidity?

Electron withdrawing groups increase an acid's ability to donate a proton.

All other things being equal, is a lone pair more stable in an sp, sp2 or sp3 orbital? How does this influence acidity?

sp>sp2>sp3 because a lone pair is more stable in s orbitals than p orbitals

Hs on sp hybridized atoms are more stable with the resultant lone pair, and therefore more acidic

Which is more stable for an acid: resonance in a ring or resonance with a carbonyl?

The carbonyl because of the electron density of O

In an acid, a smaller pKa means more or less acidic?

More acidic

Racemic mixture

Equal concentrations of enantiomers

Meso compound

A molecule with two or more stereocenters, but also containing an internal mirror plane, meaning the compound is not overall chiral

Conformations vs. Configurations

Conformations refer to the same molecule rotated around single bonds, such as chair conformations. Configurations refer to different stereoisomers wherein conversion from one to another would require the breaking of bonds.

Is the boiling point of a racemic mixture the same as that of each pure enantiomer?

No

Strong bases tend towards what types of reactions?

SN2 or E2

Rank the stability of carbocations

Tertiary>Secondary>Primary>Methyl

Greater size = ________ nucleophile

Stronger

How do allyl or benzyl groups affect the speed of an SN2 reaction?

Increase speed

Do phenols undergo substitution reactions?

No

How does protonation affect epoxide reactions?

If the oxygen is protonated, the nucleophile will attack the more substituted carbon

T/F: the H atom in an elimination in a ring must be in the same plane as the leaving group.

True

How do polar protic solvents affect SN1, SN2, E1 and E2 reactions?

Polar protic solvents stabilize the carbocations intermediate in SN1 and E1 reactions, and they do not hinder E2 reactions, but they will block the stereocenter/alpha carbon in SN2 reactions.

How does size of a molecule affect nucleophilicity in polar protic vs polar aprotic solvents?

Larger size in polar protic —> greater nucleophilicity

Smaller size in polar aprotic —> greater nucleophilicity

Do non-polar solvents favor unimolecular or bimolecular mechanisms in substitution elimination reactions?

Bimolecular, because the charged leaving group does not want to leave into a non-polar environment

Does heat favor substitution or elimination?

Elimination

What is an imine? How is it formed?

An imine is C=N:-H and it is formed via attack of a carbonyl carbon by ammonia or a derivative, with loss of water

What is an enamine? How is it formed?

An enamine is an alkene + a (substituted, usually) amine. It is formed when an ammonia or derivative attacks a carbonyl carbon with loss of water. The water then eliminates a H, allowing for formation of a C=C bond.

What is the first step in acetal formation?

Protonation of the oxygen

What are the substituents of an acetal? Hemiacetal?

Acetal: -OR, -OR, -R, -H

Hemiacetal: -OR, -OH, -R, -H

Can ethers be hydrolyzed in mildly acidic conditions?

No

Can NaBH4 reduce carboxylic acids/esters?

No

Weaker bases lead to more 1,4 or 1,2 additions in vinyl ketones?

1,4

Is a N with three different groups chiral? Why or why not?

No; the lone pair can flip sides so readily that the molecule does not retain stereochemistry.

How do organocuprates react with carbonyl carbons? Alkenes?

Organocuprates react with alkenes, but not with carbonyl carbons.

When are chromium agents used for oxidation? Manganese agents?

Chromium in acidic conditions, manganese in basic conditions

What types of chromium agents partially oxidize? Give examples. How is this different from other chromium agents?

Anhydrous chromium agents such as PCC. Other chromium agents fully oxidize.

What is the haloform reaction?

Converting methyl ketones to carboxylic acids using first a diatomic halide (e.g. I2, Br2) followed by a neutralization

How does ozone react with alkenes?

Ozone cleaves alkenes to form ketones and aldehydes

What does periodic acid cleave?

cis-1,2-diols