Hydroboration-Oxidation Orgo Lab Final

electrophilic aromatic substitution

a reaction where an electrophile replaces a hydrogen atom on an aromatic ring, preserving the aromaticity

nitration of methyl benzoate

electrophilic aromatic substitution where a nitro group (NO2) is introduced onto the aromatic ring of methyl benzoate

activating group

a substituent that donates electron density to the aromatic ring, increasing its reactivity toward electrophilic substitution

deactivating group

a substituent that withdraws electron density form the aromatic ring, decreasing its reactivity toward electrophile substitution

resonance stabilization

the delocalization of electrons across a molecule that stabilizes intermediates formed during a reaction

rate-determining step

the slowest step of a reaction that determines the overall reaction rate; in EAS, it's the attack of the electrophile on the ring

TLC (Thin Layer Chromatography)

a technique used to identify and verify the product by comparing the movement of spots on a TLC plate

aromaticity

electrophilic aromatic substitution preserves the ______ of the benzene ring

nitronium (NO2)

in the nitration of methyl benzoate, the electrophile in the ____ ion

activating

electron-donating groups are called ______ groups because they enhance the rate of substitution

deactivating

electron-withdrawing groups are called ____ groups because they decrease the rate of substitution

meta

the _____ position is where the nitro group attached in the major product of methyl benzoate nitration

the ______ bath is used during the reaction to control temperature and prevent side reactions

attack

the rate determining step in electrophilic aromatic substitution is the ____ of the electrophile by the aromatic ring

delocalized

in resonance structures of benzene, electrons are _____ across the ring

catalyst

sulfuric acid acts as a ______ in the nitration reaction, helping to generate the nitronium ion

ortho

- describes the substituents on a benzene ring that are attached to adjacent carbon atoms (positions 1 and 2)

meta

- describes the substituents on a benzene ring that are separated by one carbon atom (positions 1 and 3)

para

- describes the substituents on a benzene ring that are opposite each other (positions 1 and 4)

ortho/para directors

- substituents that are usually activating groups (strong or moderate) or weak deactivating groups

- they donate electron density and favor electrophilic attack at positions 1 and 2 or 1 and 4

meta directors

- substituents that are strong deactivating groups

- they withdraw electron density and favor electrophilic attack at positions 1 and 3

para, ortho

bulky substituents will attach at the ____ positions rather than the ___ positions due to steric hindrance

the OH substituent is a _______ that will attach at the ortho or para positions

activating

generally substituents possessing a lone pair of electrons that can be donated are _______ groups

deactivating

generally electron withdrawing substituents are ____ groups

meta

carbonyl (C=O) groups next to the benzene ring are moderately deactivating, thus direct other substituents to the ____ position

meta

-NO2, -NR3+, and -CN are all strongly deactivating and are therefore ___ directors

nitration of methyl benzoate

mixed melting point, melting point, and TLC were used to determine the identity of the product in the _______ (EAS) lab

formation of nitronium ion

step 1 of nitration

step 2 of nitration

nitronium ion

nitric acid was combined with sulfuric acid to make the ______ that became the electrophile for the nitration of methyl benzoate

fischer esterification

acid-catalyzed reaction where a carboxylic acid and an alcohol combine to form an ester and water

reversible

each step of the acid-catalyzed esterification is _____

equilibrium

appreciable concentrations of the carboxylic acid and alcohol remain at ______ in the fischer esterification reaction

fischer esterification steps

1. protonation of carbonyl oxygen

2. weakly basic ROH attacks the carbonyl carbon of the carboxylic acid

3. deprotonation

4. left with newly formed ester

reactant, product

to favor the formation of ester, one must either add an excess of one ____ (acid or alcohol) or remove a ____ (typically H2O) as it is formed

leaving group

in fischer esterification, the acid catalyst also functions to protonate the _____

odor, IR

the ester products of the fischer esterification reaction were identified by _____ and _____

alcohol, ester

because every step of the esterification is reversible, an excess of ____ will favor the formation of an ____

fischer esterification mechanism