Chem 2510 prelim #1

SN1

The conversion of 2,5-dimethylhexane-2,5-diol into 2,5-dichloro-2,5-dimethylhexane is a ___ mechanism

HCl, H2O

What are the reagents of the SN1 reaction?

Product of the E1 pathway, water

What are possible sources of contamination of the SN1 reaction?

Impure product has a larger melting point range

Compare the melting point range of a pure product in the SN1 reaction and an impure one

Pure crystals have a higher melting point

Compare the melting point of contaminated crystals to pure crystals in the SN1 reaction

IR, percent yield, melting point

Using what techniques was the product assessed for purity in the SN1 reaction?

The product is impure and was not fully converted from the 2,5-dimethylhexane-2,5-diol into 2,5-dichloro-2,5-dimethylhexane

What would it suggest if the IR spectrum of the gathered product of the SN1 reaction has a hydroxyl peak at 3300cm^-1

2,5-dimethyl-2,5-diol

Starting material of SN1 reaction

2,5-dichloro-2,5-dimethylhexane

Desired product of SN1 reaction

Vacuum filtration

To separate the product of the SN1 reaction after HCl was added to 0.25g of 2,5-dimethylhexane-2,5-diol ____ was used

To allow the product to dry even further and prevent contamination

Why was it important to use low vacuum suction to allow the crystals obtained from initial vacuum filtration in the SN1 reaction?

1:1

What is the molar ratio of product to reactant in the SN1 reaction?

Hirsch funnel

The SN1 product was filtered using a ___

Scintillating vial

The product was collected after filtration in a ___

Glass waste

Used capillary tubes would be thrown in the ___

Capillary tubes

___ were used to collect samples of product for melting point in SN1

Higher- 1 mol of product is more in g than starting material

Would the theoretical yield of product in the SN1 reaction be higher or lower than the initial amount of starting material?

Melting of an impure solid into an impure liquid has a larger change in entropy which corresponds to a lower melting point temperature

What is the melting point depression concept?

The separation and identification of a mixture of organic compounds

What is the purpose of thin layer chromatography?

The silica in TLC plate

The stationary phase of TLC is ___

The fluid that flows through the stationary phase

The mobile phase of TLC is ___

Differences in polarity of compounds contained in solvent lead them to travel varying distances on mobile phase

What leads to the separation of compounds using TLC?

Visualizing separation of compounds in a mixture

What is the purpose of using different dips under UV light for the TLC experiment?

Ferrocene, Acetyl Ferrocene, bromocresol green

Which three compounds are separated in the TLC experiment?

Decreases, decreases

As polarity increases, distance traveled ___ and Rf value ___ for compounds separated in the TLC experiment

Bromocresol green, Acetyl Ferrocene, Ferrocene

List the compounds separated by TLC in order of decreasing polarity

Increase

As the polarity of running solvent(mobile phase) increases, the Rf values of all separated compounds ___

Most polar

If the mobile phase is more polar than solid phase, which compound will travel the furthest?

False

Two spots with different Rf values can be the same compound

Distance traveled by compound/distance of solvent front

Rf value formula

Increase

Increasing the relative polarity of the solvent will ___ Rf values

Hexanes, hexanes in 10% ethyl acetate, methanol

Rank Rf values from lowest to highest of bromocresol green in hexanes hexanes in 10% ethyl acetate, and ethanol

Equilibrated

Before running the sample through the column, the column must be ___ with solvent

10% ethyl acetate in hexanes

The sample travels through the column in the mobile phase which is ___ in column chromatography

Less polar- Ferrocene

In column chromatography, which compounds elute first?

Colored compounds

In column chromatography, only the fractions which contained ___ were used to run TLC

30% ethyl acetate

Which solvent was used after Ferrocene was successfully eluted?

Methanol

Which solvent was used after Acetyl Ferrocene was successfully eluted?

Silica gel

What is the stationary phase in column chromatography?

Air pressure

In column chromatography, the solvent is forced through with ___

Greater interaction with polar silica bed

Why do more polar compounds require a more polar solvent to elute in column chromatography?

Compounds with larger Rf values elute first in a given solvent

Relate elution order and Rf values in TLC and column chromatography

UV active

UV light can only detect ___ compounds

Ones that indicate compound on grid TLC

Only ___ fractions from column chromatography should be run on analytical TLC

Mesohydrobenzoin

Starting material of oxidative cleavage experiment

Oxidize mesohydrobenzoin to 2 benzaldehyde

What is the purpose of the oxidative cleavage experiment?

Heterogenous- in different phase than reactants

What type of catalyst catalyzes the oxidation of mesohydrobenzoin to 2 benzaldehyde?

Solid, liquid, heterogenous

The catalyst in the oxidative cleavage experiment is in the ___ phase while the reactants are in the ___ phase making it a ___ catalyst

Prevent oxygen from leaking as it is necessary for the experiment and prevent ethanol from evaporating

What is the purpose of having the balloon on the round bottom flask in the water bath with the starting material in ethanol and catalyst?

The steam in

Which hose goes on top for a steam bath?

Water out

Which hose goes on bottom for a steam bath?

Bottom

For a steam bath, steam goes in on the ___ and water goes out on the ___

Flooding

What can happen if the hoses are connected improperly in a steam bath?

To separate it from the product- could contaminate the product upon analysis

Why is it necessary to evaporate the ethanol solvent after the oxidation reaction has been maintained for an adequate amount of time?

The ethanol solvent was not evaporated after the reaction conditions were ended

Ethanol peaks were seen in the Ir spectrum of the product of the oxidative cleavage reaction. What may have occurred?

Starting material- mesohydrobenzoin

If alcohol peaks are seen in the IR of the oxidative cleavage product, ___may be present

A column was run and subsequent fractions were used for TLC

What was done to purify the product and analyze its presence following the steam bath and evaporation of ethanol?

To analyze which fractions have product following the reaction and column chromatography

What is the purpose of analytical TLC in oxidative cleavage?

Ones containing compound

Which fractions should have solvent evaporated in the oxidative cleavage experiment?

Almonds

The smell of ___ indicates the presence of benzaldehyde upon evaporation of compound containing fractions

Aldehyde- benzaldehyde

A ___ peak would indicate a successful oxidative cleavage experiment

Those only containing product

The product yield of oxidative cleavage is based on which fractions?

Identify which fractions contain compound to analyze by analytical TLC

What is the purpose of analyzing fractions with grid TLC in oxidative cleavage?

It separates any starting material that is left from product thriugh polarity differences

How does running a column purify the product in the oxidative cleavage experiment?

The compounds were effectively separated by different solvents. The spaces suggest separation

In the column chromatography experiment, what do the spaces between squares with compound suggest?

High concentration of compound

What does strong color suggest on grid TLC?

A column empty of compounds following a series of fractions that contained compound

What would suggest that all compound has been eluted from a column?

Salicylic acid and charcoal

In the recrystallization experiment, benzoic acid is contaminated with ___

Dissolves a lot of compound at high temps and very little at low temps and a lot of impurities at low temps

List the characteristics of an ideal solvent for recrystallization

During boiling

When are impurities separated from the compound in the recrystallization experiment?

Filtration

____ was used to separate insoluble visible impurities after the mixture was mixed with boiling water

If too much is used much of it will not dissolve and will contaminate the benzoic scid recovered further

Why would a small amount of salicylic acid be included in the impure mixture?

Clear white crystals, lower melting point, and more narrow melting point range

What factors would indicate increased purity of the benzoic acid compound?

Grey/foamy vs white crystals, more narrow melting point range, lower

Compare the appearance melting point and melting point range of the benzoic scid recovered vs the initial mixture

Cooling

At what point do BA crystals form during recrystallization?

Excludes

As crystals form during recrystallization during cooling they form a lattice which ___ impurities

2 napthol and 1 iodobutane

What are the starting materials of the ether synthesis?

SN2

The mechanism of the ether synthesis is a ___ mechanism

2-butoxynapthalene

What is the desired product of the ether synthesis?

2 butoxynapthalene, sodium iodide, water

What are the products of the ether synthesis

Sodium hydroxide, ethanol

Reagents of ether synthesis

Reflux

This method was used for the reaction conditions of the ether synthesis

It saves ethanol

What does the condenser provide for the ether synthesis?

Lower

When conducting reflux, water goes in the ___ tube

Upper

When conducting reflux, water goes out the ___ tube

Up

In reflux, water moves ___ the condenser

To condense the ethanol vapors that are evaporating due to boiling

Why is the condenser cool in when running w reflux?

Plugging it into the wall instead of the regulator

What is a major safety hazard to avoid with a heating mantle?

Voltage regulator b

Which part of heating apparatus gets plugged into wall in SN2 ether synthesis to run reflux of NaOH, iodobutane, and 2 napthol in ethanol

Add sodium hydroxide, ethanol, 2 naphthalene to round bottom flask and reflux, add 1 iodobutane and then reflux again, pour solution over ice, isolate product by vacuum filtration

List the steps of ether synthesis experiment

Suction filtration from the beaker of ice

How is the product 2 butoxynapthalene isolated in the ether synthesis experiment?

Separate caffeine and aspirin

What is the purpose of the Anacin experiment?

Differing solubility in aqueous solutions

What difference between caffeine and aspirin allows them to be separated?

Aspirin possesses an acidic hydrogen which deprotonates in basic solutions- its conjugate base is more soluble than its acidic form

Why is aspirin more soluble than chlorine in aqueous media?

Basic

Aspirin is more soluble in ___ solutions

pH, PKa

When ___ is greater than ___ an acid is deprotonated and therefore more soluble in an aqueous solution

DCM

What is the solvent used in the Anacin extraction experiment?

Deprotonates when pH is greater than its pKa

Why is aspirin soluble in aqueous media but not organic?

Organic

Which layer of solution in separatory funnel is caffeine found in?

Aqueous

Which layer of solution in separatory funnel is aspirin found in?