L7 : Dehydration of 2-methylcyclohexanol

The alkene is removed as it forms by the process of ____ the alkene has a ____ bp than the alcohol and a lower molar mass

distillation lower

2-methylcyclohexanol is a _____ alcohol and dehydrates by the _____ mechanism.

secondary E1

provide 2 reasons why the boiling point of the parent alcohol is always higher than that of the product alkene

the alcohol molecules are strongly connected by H-bonding while the alkene only has Van Der Wall forces and boiling point increases as intermolecular forces increase.

WHat is the driving force of teh rearrangement of intermediate carbocations during dehydration of alcohols via E1

the desire to achieve the most stable carbocation by migration of either a hydride or an alkyl group to the most substituted carbon

why is cold water used during distillation?

to cool and condense the vapor into receivable liquid

why is potassium carbonate (K2CO3) added .to the distilled liquid?

to fully separate the alkene and (salty) water layers

the Br2 test is performed to test for

unsaturation of alkenes

what is the product of the addition of bromine to 1-methylcyclohexene?

1,2-dibromo-1-methylcyclohexane

what is the product of dehydration of 2-methylcyclohexanol?

1-methylcyclohexene

1. what is the first step of the E1 mechanism and why 2. what is an important part of of the E1 mechanism upon the dehydration of 2-methylcyclohexanol

1. OH is protonated because water is a better leaving group 2. carbocation rearrangement

reversal of dehydration may be avoided by (1)_____ 2. shifting an equilibrium of a reversible reaction to the right by removing one of the products as it is formed follows what principle?

1. removing the alkene 2. Le Chatelier Principle

what is the limiting reagent in this experiment?

2-methylcyclohexanol

secondary and tertiary alcohols dehydrate by which mechanism?

E1

what is the catalyst?

H2SO4

the K2CO3 also has another function at this point in the procedure- what is it?

K2CO3 is a strong base and therefore could neutralize any H2SO4 that could have gotten into the solution therefore helping yield better results

selectivity of the lower energy, more substituted alkene, higher stability configuration follows what rule? remember that an ( ___) isomer of a pair of diastereomers predominates

Zaitsev's rule E

Define Le Chatelier's principle

a principle that supports equilibrium shifts as a response to counteract a constraint such as a change i pressure, temp or concentration of the reactant that is applied to the system while in equilibrium

dehydration of 2-methylcyclohexanol involves the conversion of an alcohol into an _____.

alkene

How does the K2CO3 added to the alkene/aqueous distillate in order to fully separate the alkene and aqueous layers, accomplish its task?

an alkene is already not soluble in water but addition of k2CO3 creates "salty" water in which the alkene is immiscible

during dehydration, ___ and ___ are formed.

carbocation, water

why do secondary and tertiary alcohols need the presence of H+in order to lose their hydroxyl groups

it is better for a molecule that is removed to be stable in which is achieved through binding with the present hydrogens

the nonbonding lone pair electrons on the oxygen atom of teh hydroxyl group which is the functional group of alcohols severs as a ______which ...

lewis base which donates a pair of electrons

disappearance of the red, orange bromine color is a _______ test for unsaturation in the form of a carbon-carbon double or triple bond

positive