Organic Chemistry Lab Quiz 5: Experiment 7-10 + Spectra

Demonstrate a Diels Alder Reaction

Draw the flow of electrons

Zaitzev Rule

Empirical rule for predicting the favored alkene products in elimination reactions

Diels Alder reaction is usually

Free of side products

Neomenthyl chloride in its most stable form

Has the desired anti periplanar geometry for formation of either A or B

Markovnikov Rule

Hydrogens will add to the carbon that has the most hydrogens

Diene

- A compound containing two double bonds - Nucleophile

Dienophile

- An alkene - Electrophile

Draw the following reactions/transition states

- Diene + Dieonophile, both the thermal pathway and the photochemical way - Tetraphenyl cylcopentadienone +Benzyne - Anthranilic acid + Isopently nitrite - Furan + cyclopentadiene - Transition state for furan with maleimide - Furan + Maleic anhydride

Lucas Test

- Involves the conversion of alcohols to alkyl chlorides

Describe Characteristics of the Diels Alder Reaction

- It is not ionic yet it may be catalyzed by Lewis acids - The reaction is notable for its predictable sterochemistry and regiochemistry - It is reversible - Complies with the Woodward Hoffman Rules - Typically is allowed via thermal pathway it is not permitted via a photochemical pathway

Describe why benzene is an interesting molecule

- It is very unstable - Benzene is extremely reactive - Diels Alder is a second order reaction

Qualitative Analysis of Alcohols and Phenols (Be able to draw all of the reactions )

- Jones Oxidation - Lucas Testing - Ferric Chloride Test

Endo Adduct

- Stabilized by more extensive pi electrons overlap which causes it to form faster - Kinetic product - Generally less stable than exo

Ferric Chloride

- Test for phenols - When a phenol is present it turns the solution a red/blue/violet complex

Jones Oxidation

- Tests positive for primary or secondary alcohols Synthesizes camphore

Be able to draw

- The general scheme for an SN1 reaction - Reaction coordinate diagram for an SN1 reaction of tertiary alkyl halides

Whenever a substrate yields the less stable alekene as a major product of an elimination reaction

- There may be some sterochemical constraints inhibiting the formation of the Zaitzev product The acid catalyzed dehydration of alcohols which usually follows the Zaitzevs rule is generally believed to occur by an E1 mechanism

Exo Adduct

- Thermodynamic control product - Stable product is favored

Describe why open chain dienes succh as 1,3 butadiene can readily undergo the Diels Alder reaction

- This diene prefers an s trans conformation

Name the scientist that worked together at the University of Kazan over a century ago

- Vladimir Vasilevich Markovnikov - Alexnder Zaitzev

Alcohols follow the

4 1/2 carbon rule in the context of monofunctional groups, namely, very soluble in water from C1-C3

Describe what a mechanism is

A mechanism is a scientific hypothesis about processes that we cannot observe directly-the things that molecules do as they redistribute their atoms and are thereby transformed into new molecules

Diels Alder Reaction

A type of concerted mechanism whereby two reactants one a diene and the other a dienophile undergo a favorable alignment of their molecular orbitals to form a product - discovered in 1930

Hydroxyl groups

Increase the solubility of organic compounds by both accepting and donating hydrogen bonds functional groups that can only accept hydrogen bonds also increase the solubility of organic compounds

A simple hydrocarbon will not

Interact actively with a water molecule of an aqueous solution because it cannot break the strong hydrocarbon bonds in the molecule

Describe what the Woodward Hoffman Rule permit

It essentially predicts whether a reaction such as Diels Alder often called elctrocylic or pericyclic reaction will occur via a thermal or photochemical way

Describe what increasing polarity of a solvent does

It makes the solvent better at solvating the polarized transition state and thereby lowering the activation barrier should increase the rate of this hydrolysis

There is a clue to the origin of the Evelyn effect in the catalog of the SigmaAldrich Chemical Company where the 2-methylcyclohexanol us described as a

Mixture of cis and trans isomers. In fact it is nearly equimolar mixture of the two isomers

LeChateliers principle states

Removing a product from a chemical system at equilibrium shifts the equilibrium in the direction favoring the formation of the products

Woodward-Hoffman Rules

Rules developed to interpret and predict the reactions of dienes with eachother, dienes with dieneophiles and intermolecular interactions of the polyenes themselves

Describe the two mechanistic paths a reaction can undergo

SN1 - Unimolecular reactions that involve a step wise mechanism and occur for tertiary and some secondary alkyl halides through the formation of a carbocation intermediate - SN2 - One step biomolecular process for primary and secondary alkyl halides

Describe what happens when there is a difference in electronegativity between a carbon and a halogen

The carbon atom acquires a partial positive charge taking an electrophilic character while the halogen takes on a nucleophilic character due to its partial negative charge

What happens when a reaction could produce two or more structures but yield only one of them ?

The reaction is said to be regioselective. The Zaitzev rule works in most cases because it produces more stable alkenes

What do you do when a particular phenol is not is not that soluble in water?

Then the ferric chloride test is performed differently to accommodate for that. A few crystals or drops of the suspected phenol are dissolved in 0.5 mL DCM and 3-5 drops of the FeCL3 solution is added. One or two drops of DCM are added. Shake gently. The red, blue, green or purple color indicates a positive result.

What are the most effective water solubilizing functional groups?

Those that are capable of donating hydrogen bonds

Why has the dehydration of 2-methylcyclohexanol to a mixture of alkenes been used in labs?

To demonstrate the the application of Zaitzevs rule and the occurrence of the E1 mechanism in alcohol dehydration reactions.

Cis isomer reactions react much faster than

Trans isomer - yields a large amount of an unstable alkene

Describe how it is possible to manipulate reaction conditions

You could utilize a Lewis acid like Ag+ in a polar solvent