Analyzing organic reactions ****

Question 1

Lewis acids

Answer 1

are electron acceptors; they have vacant orbitals or positively polarized atoms

Question 2

Lewis bases

Answer 2

are electron donor; they have a lone pair of electrons and are often anions

Question 3

bronsted-lowry acids

Answer 3

proton donors; base accepts protons

Question 4

amphoteric molecules

Answer 4

can act as . either acids or bases, depending onr eaction conditions. Water is a common example of an amphoteric molecule.

Question 5

acid dissociation constant, ka

Answer 5

measure of acidity. Pka is negative log of Ka. A lower pka is a stronger acid. pKa decreases down the periodic table and increases with electronegativity

Question 6

alpha hydrogens

Answer 6

connected to the alpha carbon

Question 7

basic functional groups

Answer 7

amines and amides

Question 8

acidic functional groups

Answer 8

alcohols, aldehydes, carboxylic acids, and carboxylic acid derivatives.

Question 9

Nucleophiles

Answer 9

nucleus-loving. contains lone pairs or pi bonds. They have increased electron density and often carry a negative charge. Charge, electronegativity, steric hindrance, and the solvent can all affect nucleophilicity. Amino groups are common nucleophiles

Question 10

what is the difference between nucleophilicity and basicity

Answer 10

they are similar, but nucleophilicity is kinetic and basicity is thermodynamic.

Question 11

electrophiles

Answer 11

are electron loving and contain a positive charge or are positively polarized. More positive compounds are more electrophilic. Alcohols, aldehydes, ketones, carboxylic acids, and their derivatives act as electrophiles

Question 12

Leaving groups

Answer 12

are molecular fragments that retain the electrons after heterolysis. Best leaving groups can stabilize additional charge through resonance or induction. Weak bases make good leaving groups. Alkanes and hydrogen ions are almost never leaving groups because they form reactive anions.

Question 13

unimolecular nucleophilic substitution (SN1) reactions

Answer 13

proceed in two steps. In the first step the leaving group leaves, forming a carbocation, an ion with a positively charged carbon atom. In the second step the nucleophile attacks the planar carbocation rom either side, leading to a racemic mixture of products. SN1 reactions prefer more substituted carbons because the alkyl groups donate electron density and stabilize the positive charge of the carbocation. The rate of an SN1 reaction is dependent only on the concentration of the substrate. rate = k[R-L]

Question 14

bimolecular nucleophilic substitution (SN2) reactions

Answer 14

proceed in one concerted step. Nucleophile attacks at the same time as the leaving group leaves. the nucleophile must preform a backside attack, which leads to an inversion of stereochemistry. The absolute configuration (r or s) changes if incoming nucleophile and the leaving group have the same priority in the molecule. SN2 reactions prefer less-substituted carbons because the alkyl groups create steric hindrance and inhibit the nucleophile form accessing the electrophilic substrate carbon. The rate of an SN2 reaction is dependent on the concentrations of both substrate and nucleophile: rate = k[Nu:][R-L]

Question 15

oxidation state of an atom

Answer 15

is the charge it would have if all its bonds were completely ionic. CH4 is the lowest oxidation state of carbon (most reduced); CO2 is the highest (most oxidized). Carboxylic acids and carboxylic acid derivatives are the most oxidized functional groups; followed by aldehydes, ketones, and imines; followed by alcohols, alkyl halides, and amines.

Question 16

oxidation

Answer 16

increase in oxidation state and is assisted by oxidizing agents.

Question 17

oxidizing agents .

Answer 17

accept electrons and are reduced in the process. They have a high affinity for electrons or an unusually high oxidation state. They often contain a metal and a large number of oxygens.

Question 18

primary alcohols

Answer 18

can be oxidized to aldehydes by pyridinium chlorochromate (PCC) or to carboxylic acids by a stronger oxidizing agent, like chromium trioxide (CrO3) or sodium or potassium dichromate (Na2Cr2O7 or K2Cr2O7).

Question 19

secondary alcohols

Answer 19

can be oxidized to ketones by most agents

Question 20

aldehydes

Answer 20

can be oxidized to carboxylic acids by most oxidizing agents.

Question 21

reduction

Answer 21

is a decrease in oxidation state and is assisted by reducing agents.

Question 22

reducing agents

Answer 22

donate electrons and are oxidized in the process. They have low electronegativity and ionization energy. They often contain a metaland a large number of hydrides.

Question 23

Aldehydes, ketones, and carboxylic acids can

Answer 23

be reduced to alcohols by lithium aluminum hydride (LiAlH4).

Question 24

Amides can be reduced to alcohols by

Answer 24

LiAlH4

Question 25

esters can be reduced to a pair of alcohols

Answer 25

by LiAlH4

Question 26

nucleophile-electrophile an oxidation-reduction reactions

Answer 26

tend to act at the highest-priority (most oxidized) functional group

Question 27

one can make use of steric hindrance properties to

Answer 27

selectively target functional groups that might not primarily react, or to protect functional groups. Diols are often used as protecting groups for aldehyde or ketone carbonyls. alcohols may be protected by conversion to tert-butyl ethers.

Question 28

steps for problems solving

Answer 28

1. know your nomenclature 2. identify the functional groups 3. identify the other reagents 4. identify the most reactive functional groups 5. identify the first step of the reaction 6. consider stereoselectivity .

Question 29

some Nucleophiles

Answer 29

``` CHON carbon hydrogen oxygen nitrogen if has these with lone pair or negative sign . ```

Question 30

How does charge, electronegativity steric hinderance, and solvent affect nucleophiles

Answer 30

Charge-Nucleophilicity increases with increasing electron density (more negative charge) Electronegativity: Nucleophilicity decreases as electronegativity increases because these atoms are less likely to share electron density steric hinderance: bulkier molecules are less nuclephilic solvent: protic solvents can hinder nucleophilicity by protonating the nucleophile or through hydrogen bonding

Question 31

Heterolytic reactions

Answer 31

are essentially the opposite of coordinate covalent bond formation: a bond is broken and both electrons are given to one of the two products. Weak bases are more stable with an extra set of electrons making them good leaving groups

Question 32

oxidizing levels of functional groups

Answer 32

Level 0: no bonds to heteroatoms, alkanes Level 1: alcohols, alkyl halides, amines Level 2: aldehydes, ketones Level 3: carboxylic acids, anhydrides, esters, amines Level 4: four bonds to heteroatoms, carbon dioxide .