ochem lab final exam
What kind of reactions do alcohols do?
oxidation, subsitution, and elimination
Ketone
~1700 cm^-1 (carbonyl)
Internal alkyne IR
~2000 Its a tiny peak :)
Alkane IR
~3000 cm^-1 The signals directly to the right belong to C-H attached to the sp3 carbon.
Alkene (c=c-H) IR
~3070 cm ^-1
Alkyne IR
~3300 cm ^-1
What is IR spectroscopy signals are found in the nitration of methyl benzoate experiment?
(1) 3000 cm^-1: C-H stretch (2) 1700 cm^-1: carbonyl (3) 1502 cm^-1: NO2
What are the 3 steps of the aspirin synthesis mechanism?
(1) Activation of carbonyl group by protonation of carbonyl oxygen. (2) Nucleophilic addition of alcohol to carbonyl forms tetrahedral intermediate. (3) Elimination of water from tetrahedral intermediate restores carbonyl group.
What are the four catalysts used in the aspirin experiment?
(1) Sodium acetate (CH3OONa) (2) pyridine (C5H5N) (3) boron trifluoride etherate (BF3Et2O) (4) sulfuric acid. (H2SO4)
What are the three steps in the mechanism for the nitration of methyl benzoate experiment?
(1) generation of the nitronium ion (2) creation of the resonance stabilized carbocation. (3) The SoH3 takes the H to restore aromaticity and yield the final product.
HDI
-If the HDI is more than 4, assume it's a benzene ring. -HDI of 1 is probably a double bond, or a ring.
What is the chemical shift for CH3?
0.90
Secondary amine IR
1 signal due to the presence of one N--H bond. ~3200 cm^-1
What is the name of the final product in bromination of stilbene?
1,2-dibromo-1,2-diphenalethane
If you want to make a tertiary alcohol, what starting material do you need?
A ketone
What is the product if the starting material is a secondary alcohol?
A ketone
What is a protic solvent?
A solvent that contains H atoms attached to a electronegative atom. If a solvent is protic, then SN1 will occur.
What is the end product for the Grinyard experiment?
A tertiary alcohol; triphenylmethanol
In the synthesis of dibenzalacetone reaction (aldol experiment) what is the nucleophile?
Acetone
What is the first step of lidocaine synthesis?
Acylation
What is the drying agent used for the lidocaine synthesis experiment?
Anhydrous potassium carbonate. We used this to dry the organic phase after filtration in part b.
Why is the OH stretch so broad?
Because of extensive hydrogen bonding.
Why are aldehydes more reactive than ketones?
Because of sterics and electronic factors. The nucleophile has more room to attack the carbonyl on an aldehyde because it only has one Ch3 in comparison to the ketone, which has 2. Carbonyl is more polarized in aldehydes, therefore they are more reactive.
What is a meso compound?
Chiral centers that offset one another due to symmetry. The net result is an optically inactive compound. In essence, meso compounds are actually a chiral. They can be identified by finding a plane of symmetry that divides the compound into two mirror images. In bromination of stilbene, this is the product when cis-stilbene is the starting material.
What happens if we treat cyclohexanol with a base instead of an acid?
Deprotonation of the reactant.
What type of reaction is observed in the preparation of cyclohexene experiment?
E1.
What kind of reaction is bromination of stilbene?
Electrophilic addition reaction
What type of reaction is the nitration?
Electrophilic aromatic substitution
If we want to make a primary alcohol, what should be our starting material?
Formaldehyde
What is chemical shift?
Gives us information about the chemical environment of each type of hydrogen.
What is the reagent used in the preparation of cyclohexene experiment?
H3PO4 (phosphoric acid)
What is the reagent in the preparation of tert-butyl chloride reaction?
HCl
What is the reagent for the nitration experiment?
HNO3 and H2SO4
What is the oxidizing agent of the oxidation of cyclohexanol experiment?
HOCl Created using NaOCl and acetic acid.
What did we use to dissolve furan in part II the Diels alder experiment?
Hexanes and ethyl acetate.
What does the number of signals on an NMR tell us?
How many non-equivalent H are present.
How do we use IR to decide if we need to do distillation in the preparation of cyclohexene experiment?
If we see the OH stretch, then we need to distill again because it is an indicator that there is still some OH products (impurities) within the product. (Remember yield is lower if you distill again)
What is anhydrous ether?
It is a very strong base and will react with substances that are protonated (water). Another reason why we need dry glassware for the grinyard experiment.
What is sodium acetate used for the lidocaine experiment?
It is used to react with the HCl left over after acylation. If we leave the HCl there, it can protonate the amine, and it will not be able to attach the carbonyl carbon.
What is the role of sulfuric acid in the nitration mechanism?
It makes OH on the nitrate a better leaving group (water) by protonating it.
What is HCl used for in the lidocaine experiment?
It's added to the filtrate while in the separatory funnel. (I couldn't figure out why we used it, but I think it was just for separating the layers/extraction purposes.)
What is the final product after alkylation?
Lidocaine
What is the final product after the lidocaine is treated with H2SO4 in anhydrous ethanol?
Lidocaine bisulfate
What is the starting material in the preparation of t-butyl chloride experiment?
tert-butyl alcohol
In dehydration of alcohol, what is the leaving group?
water
What kind of reaction is the Grinyard reaction that we did in the lab?
Substitution (SN1?)
What is the first step of the synthesis of dibenzalacetone reaction?
The OH from the base takes the H from the ketone to yield the enolate.
Cis and trans stilbene are _____________.
Stereoisomers.
What is the chemical shift for CH2?
1.20
What is the chemical shift for CH?
1.50
How many moles of diethylamine is needed for the alkylation step of lidocaine synthesis?
2 moles
Primary amine IR
2 signals due to the presences of 2 N--H bonds. ~3200-3300 cm^-1
What is the nucleophile in lidocaine synthesis when preparing the alpha-chloro-2,6-dimehtylacetanilide?
2,6-dimethylacetanilide
What part of the lidocaine experiment represents the process of acylation?
2-6-dimethylaniline being treated with acyl chloride. This yields the chloro-2,6-dimethyl acetanilide.
What is a racemic mixture?
50/50 mixture of two enantiomers. In terms of the bromination experiment, it is what results when trans stilbene is the starting product.
What is the product if phenyl magnesium bromide reacts with water? (grinyard)
A benzene. This is what we do not want and is why we had to ensure the glassware was extremely dry for the Grinyard experiment.
What is the relationship between bond strength and wave number?
Stronger the bond, larger the wavenumber. Ex: C=C will have a larger wave number than C-C.
What is the starting material for the nitration experiment?
Methyl benzoate
What is the final product for the nitration experiment?
Methyl-(beta)- nitrobenzoate.
What is the base used in the synthesis of dibenzalacetone reaction?
NaOH
Tertiary amine IR
No N--H signal, because there is only a C-N bond.
pryidinium chlorochromate (PCC)
Oxidizing agent used to convert a primary alcohol into an aldehyde.
What is the nucleophile for the Grinyard experiment?
Phenylmagnesium bromide
oxidation number
Positive or negative number that indicates how many electrons an atom has gained, lost, or shared to become stable.
What is the source of bromine used in the bromination of stilbene experiment?
Pyrimidine tribromide
What kind of reaction is the preparation of tert-butyl chloride?
SN1
What is an aprotic solvent?
Solvent that contains no H atoms connected directly to an electronegative atom. If a solvent is aprotic, then SN2 reaction will occur.
What is the chemical equation for lidocaine synthesis?
Steps: (1) acylation (2) alkylation (3) formation of the salt
Why may a carbonyl stretch be shifted?
The effect pf the conjugated bond, there is an electron withdrawing effect. Resonance can also lower the wave number of the carbonyl, because the bond becomes weaker.
Which molecule in the synthesis of dibenzaldehyde mechanism serves as the initial enolate?
The ketone
What is the relationship between mass and wavenumber?
The lighter the atom, the larger the wavenumber.
What happens if there is only one mole of the benzaldehyde present?
The molecule will look like the dibenzaldehyde cut in half. The reaction would not go further than the formation of the second enolate.
What does deshielded mean?
The nucleus of the atom is experiencing a stronger magnetic field, and therefore will appear downfield in the NMR.
What does shielded mean?
The nucleus of the atom is experiencing a weaker magnetic field, and therefore will appear upfield on the NMR.
What happens when the sample size is too large for melting point determination?
The sample will require more energy to melt it and the temperature range will broaden. This results int eh sample being falsely labeled as an impurity. Sample size must be 2-3 mL up the ca
What is the nucleophile in bromination of stilbene mechanism?
The stilbene
What is the purpose of the nitrate and sulfuric acid in the nitration experiment?
To generate the electrophile; nitronium
What is NaOH used for in the lidocaine experiment?
To neutralize the acidic extract.
What is bisulfite used for?
To reduce the hypochlorite. (** idk what it is reduced to ??)
What happens when we do a mixed reaction with aldehydes and ketones in which both have alpha hydrogens?
We get a mix of 4 final products. This is not favorable for aldol reactions. To remedy this, we have to ensure at least one of the two have no alpha hydrogens.
Why do we was the product in the preparation of cyclohexene experiment?
We use NaCl to "salt out" the product. It pushes out the unwanted substances so all we collect is the pure product.
What is the electrophile used in the acylation step of lidocaine synthesis?
acyl chloride
What part of the lidocaine experiment represents the process of alkylation?
alpha-chloro-2,6-dimethyl acetanilide treated with toluene, heat, and TWO moles of dimethylamine. This yields the lidocaine.
What was the dienophile used in the Diels alder experiment?
maleic anhydride
What kind of reaction is lidocaine synthesis?
nucleophilic substitution reaction (SN2)
What were the dienophiles used in the Diels alder experiment?
part I--> (R)-(-)-(alpha)- phellandrene part 2--> furan
isolated diene
pi bonds are separated by two or more sigma bonds