Organic Chemistry II - Lab Final
Mechanism of Fischer Esterification.
**long af mechanism, look in your notes.
Different methods to assist in the formation of the Grignard Reagent. Mechanism for Grignard Reaction and its application.
- Diethyl ether or THF assist in the formation of this reagent as it can be dried and it helps solubilize the reagent (by coordinating to the positively charged magnesium). - Mechanism involves the formation of the reagent and its R group, The reagent attacks the carbon of a carbonyl. The carbonyl bears the R group of the reagent and the O of the carbonyl becomes protonated to form OH.
Structural difference between Methyl ketones and other ketones and the test to distinguish between the two.
- Methyl Ketones have two R groups, with both being methyl groups. - But in general all ketones have two R groups and no H groups. - Iodoform is a test to distinguish.
Formation of Grignard Reagent (What is different about it? Function as a carbon nucleophile) Why are the reaction conditions to be maintained anhydrous?
- Prepared by reacting an alkyl or alkyl halide with magnesium metal. - Extremely polarized causing the carbanion to be a very strong base, a very powerful nucleophile, capable of reacting with a wide variety of electrophiles (including carbonyl carbons.) - this reagent will remove a proton from water and be hydrolyzed, thus it needs to be anhydrous.
What is the purpose of forming Acetanilide (Protecting group)
- The formation of this group: The amide nitrogen does not activate the ring towards substitution as much as the free amino group of the aniline, but it can still exert its ortho/para- directing influence.
Reversible Reactions and Concept of Equilibrium.
- This particular reaction is when products interact with one another and can be reacted to form the reactants or go in reverse. Reaction can occur in the forward or reverse direction. - This concept involves when the forward and reverse reaction rates are equal.
What is Reflux? Why are reactions subjected to reflux? / What are advantages of reflux? Difference between reflux and distillation.
- involves heating the chemical reaction for a specific amount of time, while continually cooling the vapour produced back into liquid form, using a condenser. The vapours produced above the reaction continually undergo condensation, returning to the flask as a condensation. - speeds up the reactions of those that take forever to occur. - condenser allows for no vapor to escape and thus no product escapes. - distillation = a liquid is heated until it is boiling. The vapor which is produced is condensed and collected in a separate flask. best for separation due to different boiling points. - reflux = the liquid is boiled, but the vapor is allowed to condense and flow back into the original flask. best for dissolving stubborn compounds.
What's the relationship between borneol, isoborneol, and camphor? Review the reaction conditions for the oxidation of isoborneol Review the chirality of camphor, borneol, and isoborneol
Camphor is the product of isoborneol. But when reduced back, can form either borneol or isoborneal. This is due to which face the camphor attacks on the carbonyl. # chirality of camphor = 2 & enantiomers of each other # chirality of borneol = 2 # chirality of isoborneol = 2 (borneol and isoborneol are enantiomers of each other).
Steric and Electronic Effects (ortho-para or meta directing effects) of substituents on Electrophilic Aromatic Substitution.
Due to the bulkiness of the Acetanilide, the substitution occurring predominantly at the para- substitution.
Steric and Electronic Effects (ortho, para or meta directing effects) of substituents on Electrophilic Aromatic Substitution.
Electron Withdrawing Groups = direct meta. Deactivates the ring, making it harder to react. ** Does not work with Friedal Craft Electron Releasing Groups = direct ortho and para. Activates the ring, making it easier to react. ** Halogen direct ortho and para, although it is mildly withdrawing.
Dehydration of the Aldol product (Why does this sometimes occur?)
If the aldol is not isolated, it can become dehydrated and removal of water occur. It causes the OH group of the aldol to leave and form a conjugated system (as it leaves a double bond in its place). It forms a beta-ketoester.
Role of Sodium Bicarbonate washing.
Neutralizes any unreacted/excess acid in the fischer esterification reaction.
Effect of temperature on nitration products.
The higher the temperature, the more nitration groups placed on the benzene ring.
Different ways of pushing the Fischer esterification process in the forward direction. Role of glacial acetic acid and sulfuric acid.
The use of excess of starting acid will push this process into continuing forward. Both acids are acid catalysts.
Role of Sulfuric acid.
This acid acts as an acid catalyst, it protonates and cause the formation of a cation.
Use of Hydrochloric acid during isolation of the product.
This acid reacts with any unused Mg turnings. (exothermic reaction).
Mechanism for the formation of an imine (Reaction of an aldehyde or ketone with any generic amine) and application to reaction of carbonyl compounds with 2,4- dinitrophenylhydrazine (2,4-DNP) and semicarbazide.
This mechanism involves a carbonyl and an amine. The oxygen within the carbonyl is replaced with the amine and its R group. (C=O --> C=NH2-R) - semicarbazide is NH2-H2NCONH - 2,4 ditrnitrophenylhydrazine is NH2-NH-benzene ring with a nitro group at 2 and 4.
Mechanism of Cannizzaro Reaction.
This mechanism involves the -OH of the base attacking the carbon of the carbonyl. This compound (with the added OH group) attacks another carbonyl forming a carbonyl with an negative oxygen group, and another compound with an carbon-OH group.
Mechanism of Aldol Condensation. ( Formation of the ALDOL)
This mechanism involves the enolate anion attacking a carbonyl carbon (electrophile - one that is identical to the the carbonyl that formed the enolate) to form a new carbon-carbon bond (basically the combination of two carbonyls). The oxygen that becomes negatively charged due to the formation of the new C-C bond, becomes OH due to the addition of water.
Hydrolysis of Nitroacetanilide and Mechanism.
This mechanism involves the formation of the acetanilide from aniline and acetic anhydride. - Then the acetanilide is attacked by nitration and directs a nitro group para to the acetyl group.
Mechanism for Electrophilic Aromatic Substitution. Steric and Electronic Effects (ortho, para or meta directing effects) of substituents on Electrophilic Aromatic Substitution.
This mechanism involves the formation of the nitronium ion, the attack of this ion on a benzene ring with a methyl benzoate group (substituent with a carbonyl and an ester-methyl group) to form a nitro group in either ortho, para, or meta.
Mechanism for Iodoform Reaction.
This mechanism involves the hydrogens on the alpha carbon in a carbonyl carbon to be removed by a base forming an enolate anion. the enolate anion attacks a nucleophile (iodine) with one of the iodine becoming a substituent on the anion. The carbon-iodine bond is attacked by excess base in the solution and acts as a leaving group. This leaving group is the yellow ppt.
Mechanism of formation of Nitronium ion.
This mechanism is the processor taking concentrated HNO3 and protonating it using H2SO4 to form its cationic ion.
What is the side reaction possible? (Cannizzaro) Why? What steps can you take to prevent this side reaction?
This occurs when a carbonyl is un-enolatable..or it does not have the hydrogens on an alpha carbon to be removed. With a strong base, it will cause reduction of the compound. - prevention = using a mild base, using a compound that has an alpha carbon with hydrogens.
Formation of carbanion or the enolate using NaOH.
This process is similar to iodoform. The alpha carbon's hydrogens are removed via the NaOH (strong base) to form the enolate anion.
Qualitative Tests for Aldehydes and Methyl Ketones.
To test for Aldehydes = Tollen's Test (Silver Mirror). Product is silver. To test for Methyl Ketones = Iodoform. Product is yellow.
What is an Electrophile?
a compound that has a positive charge/cation. is electron poor and needs electrons.
Be able to draw a plausible mechanism for the reactions covered. Most important information can be found in the handout on Canvas
refer to PDF.
Le Chatelier's Principle.
states that when a system experiences a disturbance (such as concentration, temperature, or pressure changes), it will respond to restore a new equilibrium state. - Ex. if more reactants are added to a system, the reaction will generate more products to offset the change and restore equilibrium.
Why can Aniline not be nitrated directly?
the bare NH2 group of the aniline is a very reactive and will oxidize or it will react with the nitric acid due to its basic nature.
Method and Mechanisms of forming Alkyl Electrophiles
this mechanism involves the process of taking an alkyl halide and an acid catalyst to transform it into an electron-poor compound.
Mechanism for Electrophilic Aromatic Substitution.
this mechanism involves the process of taking an electrophile and reacting it with the electron rich benzene ring. substitutes the double bond with a substituent.
Role of Ammonium Hydroxide.
wtf what is this