What is the common name for 1.4-Oxacyclohexane?
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Pyran.
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What is the common name for 1.4-Oxacyclohexane?
Pyran.
What are mixed or unsymmetrical ethers?
Ethers where the two groups attached to oxygen are different.
What type of molecules are ethers?
Polar molecules.
What are crown ethers commonly used for?
They are used as phase transfer catalysts.
What mechanism is involved when one of the alkyl groups in an ether is tertiary?
S N 1 mechanism.
What type of substitution occurs in the mechanism of ether formation?
Substitution can occur via S N 1 or S N 2 mechanisms.
What is the Williamson ether synthesis?
A method for the formation of ethers.
How can 2-methoxy-2-methylpropane be synthesized?
By reacting alkoxide ion with 1° haloalkanes in Williamson synthesis.
What slight property do ethers exhibit?
Ethers show slight basicity.
What are epoxides also known as?
Oxiranes.
What is the p-Claisen rearrangement?
A specific type of Claisen rearrangement where the substituent is in the para position.
What happens when ethers dissolve in strong mineral acids?
They form oxonium salts.
Why does phenol not react further to give iodobenzene?
Because the sp2 hybridized carbon of phenol cannot undergo the SN reaction needed for conversion to iodide.
Which alkyl group forms the alkyl iodide in an S N 1 mechanism?
The tertiary alkyl group.
How do ethers behave chemically?
Ethers are more or less inert in nature.
What are crown ethers?
Large cyclic polyethers that resemble the shape of a crown.
What are epoxides also known as?
Oxiranes.
How do ethers behave in organic solvents?
Ethers are readily soluble in organic solvents.
Under what conditions are oxonium salts stable?
At low temperature.
What can peroxides formed from ethers cause during distillation?
Violent explosions.
How is the presence of peroxides in ether detected?
By shaking ether solution with ferrous ammonium sulfate and potassium thiocyanate, resulting in a red color.
How can ethers be derived from alcohols?
By the elimination of a water molecule from two alcohol molecules.
What type of mechanism is involved in base catalyzed ring opening reactions?
S N 2 Mechanism.
What is another method for synthesizing epoxides?
From halohydrins.
What is a unique property of crown ethers that enhances their applications?
Their ability to selectively bind specific cations.
What is the mechanism of alkoxymercuration–demercuration of alkenes similar to?
Oxymercuration–demercuration of alkenes used for preparation of alcohol.
What mechanism does the Williamson ether synthesis occur by?
S N 2 mechanism.
What are crown ethers?
Large cyclic polyethers that resemble the shape of a crown.
How are ethers classified?
As open chain, cyclic, saturated, unsaturated, and aromatic ethers.
What is a key characteristic of ethers in comparison to alcohols?
Ethers do not possess replaceable active hydrogen.
How do the boiling points of ethers change with molecular mass?
Boiling points increase with an increase in molecular mass.
What is the hetero atom in epoxides?
Oxygen.
What type of mechanism occurs when the alkyl groups in an ether are primary or secondary?
S N 2 mechanism.
What is the role of concentrated sulfuric acid or phosphoric acid in ether preparation?
They catalyze the condensation of two alcohol molecules with the elimination of water.
What do oxonium ions give back in an aqueous medium?
They give back ether.
In which medium does the nucleophile attack the less substituted carbon during the cleavage of unsymmetrical epoxides?
In basic medium.
What are epoxides?
Cyclic ethers with a three-membered heterocyclic ring, where one carbon is replaced by oxygen.
What are cyclic ethers named as?
Oxides or epoxy compounds.
What is Ziesel’s method?
A method for the cleavage of ethers.
What is the common name for Methoxybenzene?
Anisole or Methyl phenyl ether.
What is the Claisen rearrangement reaction?
A chemical reaction that involves the rearrangement of allyl vinyl ethers to form γ,δ-unsaturated carbonyl compounds.
How do crown ethers facilitate chemical reactions?
By solubilizing cations in organic solvents.
In what type of reactions are crown ethers often utilized?
In reactions involving alkali and alkaline earth metals.
What ions catalyze the reaction to form ethers?
H+ ions.
In which medium does the nucleophile attack the more substituted carbon during the cleavage of unsymmetrical epoxides?
In acid medium.
What are epoxides also known as?
Oxiranes.
What happens when 2° and 3° haloalkanes are used in Williamson synthesis?
They predominantly form alkenes instead of ethers.
What reactions are associated with epoxides?
Acid and base-catalyzed ring opening, and reactions with Grignard and organolithium reagents.
How are most ethers named?
By their common names, with alkyl or aryl groups prefixed before the word 'ether'.
Why are crown ethers named so?
Because their macrocyclic shape resembles that of a crown.
Why do ether molecules have lower boiling points than isomeric alcohols?
Because ether molecules are not associated through hydrogen bonding.
What does the nucleophile I- attack in the S N 2 mechanism?
The least substituted carbon of the oxocation.
How does the alkoxy group affect the activation of the aromatic ring?
It activates the aromatic ring towards electrophilic substitution, similar to phenol.
What is the role of sodium borohydride in the alkoxymercuration–demercuration process?
It reduces alkoxyalkyl mercury compounds to form ether (demercuration).
Do ethers easily undergo oxidation or reduction?
No, ethers do not get oxidized or reduced easily.
What occurs in the p-Claisen rearrangement when two ortho positions are blocked?
Inversion of the ally group due to one [3,3]-sigmatropic rearrangement.
What is the Claisen rearrangement?
A chemical reaction involving the rearrangement of allyl vinyl ethers to give γ,δ-unsaturated carbonyl compounds.
In unsymmetrical ethers, how is the parent hydrocarbon determined?
The larger alkyl group is chosen as the parent hydrocarbon.
What are epoxides also known as?
Oxiranes.
What is the general structure of an ether?
R-O-R’
What is the effect of the lone pairs of electrons on etheral oxygen?
Oxygen readily coordinates with electron deficient molecules or Lewis acids.
What is one method for preparing ethers?
By dehydration of alcohols.
What is the Williamson ether synthesis?
The most important method for laboratory preparation of ethers, involving heating a haloalkane with sodium or potassium alkoxide.
Is the alkoxy group more or less activating than the phenolic group?
It is less activating than the phenolic group.
What type of mechanism is involved in the Claisen rearrangement?
Intramolecular mechanism.
What happens to the ally group in the o-Claisen rearrangement?
Retention of the ally group due to two [3,3]-sigmatropic rearrangements.
How can ethers be structurally considered?
As dialkyl (or aryl) derivatives of water.
How do ethers compare in density to water?
Ethers have lower density than water.
What is the structure of epoxides?
Cyclic ethers with a three-membered heterocyclic ring containing oxygen as the hetero atom.
What is the o-Claisen rearrangement?
A specific type of Claisen rearrangement where the substituent is in the ortho position.
In an S N 2 mechanism, which alkyl group forms the alkyl iodide?
The lower alkyl group.
What is created in step 2 of the S N 1 mechanism when the leaving group departs?
A more stable tertiary carbocation.
What basic property do ethers possess?
Ethers possess basic properties due to the lone pairs on etheral oxygen.
What is intramolecular Williamson synthesis?
A process where haloalcohols react in the presence of hydroxide ions to produce cyclic ethers.
How do ethers compare to alcohols in terms of reactivity?
Ethers are less reactive than alcohols because they do not have active hydrogen attached to oxygen.
What is the common name for Oxacyclopentane?
Tetrahydrofuran (THF).
In the IUPAC system, how are ethers classified?
As alkoxy derivatives of alkanes, named as alkoxyalkanes.
What are the general features of the Claisen rearrangement?
It involves thermal rearrangement and typically requires heat to proceed.
What are the two types of ring opening reactions mentioned?
Base catalyzed and acid catalyzed ring opening reactions.
What type of reactions do aromatic ethers undergo?
Electrophilic substitution reactions.
What happens to ethers when exposed to air and light?
They undergo spontaneous auto-oxidation and form peroxide derivatives.
What mechanism does the electrophilic substitution in aromatic ethers follow?
The Arrhenium ion mechanism.
What type of rearrangement is the Claisen rearrangement classified as?
[3,3]-Sigmatropic rearrangement reaction.
What is the significance of crown ethers in organic synthesis?
They play an important role in complexation and catalysis.
What are symmetrical ethers?
Ethers where the two groups attached to oxygen are the same.
What type of mechanism is involved in acid catalyzed ring opening reactions?
S N 1 Mechanism.
What is one application of crown ethers in analytical chemistry?
They are used for the extraction of metal ions.
How do ethers react with acids to form oxonium salts?
The lone pair of electrons on etheral oxygen reacts with the proton of an acid.
What type of ethers is the Williamson synthesis most suitable for?
Mixed or unsymmetrical ethers.
How can peroxides in ether be destroyed?
By the addition of Fe(II) salts.
What indicates the presence of peroxides when testing with ferrous ammonium sulfate?
The appearance of a red color due to the formation of ferrithiocyanate complex.
Why do 2° and 3° haloalkanes form alkenes in Williamson synthesis?
Because alkoxides, being strong bases, abstract β-protons, leading to elimination (dehydrohalogenation) instead of substitution.
What physical state are lower members of ethers like methoxymethane and methoxyethane?
Gases.
What is the common name for Methoxymethane?
Dimethyl ether.
What is one method for synthesizing epoxides from alkenes?
Epoxidation of alkenes.
What is a common method for the manufacture of ethylene epoxide?
Using ethylene and oxygen in the presence of a catalyst.
What directing effect does the alkoxy group (-OR) have in electrophilic substitution?
It is ortho-para directing.
What compounds are formed during the alkoxymercuration of alkenes?
Alkoxyalkyl mercury compounds (alkoxy mercuration).
What role does the alkoxide ion play in the Williamson ether synthesis?
It acts as a nucleophile attacking the polar carbon–halogen bond of haloalkane.
What is the reactivity of ethers towards alkalis and dilute acids?
Ethers show inert behavior towards alkalis and dilute acids in cold.
What is Zeisel's method used for?
Estimation of methoxy (-OCH3) group.
What is the physical state of higher members of ethers?
Low boiling, volatile liquids.
What class of compounds do ethers belong to?
Oxygen-containing organic compounds that are derivatives of alcohols.
What is the structure of ethylene oxide?
It is a three-membered cyclic ether (epoxyethane).
What is autoxidation in the context of ethers?
A chemical reaction where ethers react with oxygen to form peroxides.
