Glossary of Organic 2 2

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carbonyl and amine
geminal dihalide
carbon with two halogens bonded to it
vicinal dihalide
two adjacent carbons both bonded to halogens
carbon with an -OH and -OR group along with one -R group
carbon with an -OH and -OR group along with two -R groups
mesyl group
sulfur with single bonded methyl group and two double bonded oxygens
tosyl group
sulfur with single bond to aromatic cyclohexane group and two double bonded oxygens
acetyl group
carbon with a carbonyl group as well as a terminal methyl group
acyl group
carbon with a carbonyl group and an R group
anhydride group
Two carbons each connected to R groups as well as carbonyls, connected together via an oxygen
aryl group
aromatic cyclohexane
benzyl group
aromatic cyclohexane bonded to a methyl group
two nitrogens bonded together via single bonds
nitrogen double bonded to an R group as well as a single bond to another nitrogen
vinyl group
two double bonded carbons
vinylic group
two double bonded carbons with a halogen bonded to one
two double bonded carbons with a methyl group bonded to one
carbon triple bonded to a nitrogen
carbon single bonded to an R group and single bonded to an NRH, and double bonded to a CR2.
a tautomer of en enamine, wherein the double previously double bonded CR2 group's double bond shifts to a single bond, providing electrons for a C=N-R group to be created
carbon single bonded to two R groups, and a =N-OH group.
carbon single bonded to one oxygen and double bonded to another
a nitrogen double bonded to an oxygen
conformational isomers
different spatial arrangements of the same molecule. rotations around a sigma-bond
structural isomers
same molecular formula but different bond-to-bond connectivity
molecules that differ in reflections
exactly the same reflections of molecules
rotates plane polarized light clockwise
rotates plane polarized light counter clockwise
two molecules with the same molecular formula and the same bond-to-bond connectivity that are not the same compound
what are two examples of stereoisomers?
enantiomers and diastereomers
what is resolution?
the separation of enantiomers
how do enantiomers relate chemically and physically?
they have the same chemical and physical characteristics except with reactions with other chiral compounds and reactions with polarized light
what are diastereomers?
they have the same molecular formula, have the same bond-to-bond connectivity, are not mirror images of eachother and are not the same compound
what is a geometric isomer?
they exist due to hindered rotation about a bond. Cis-isomers and Trans-isomers are examples
Do geometric isomers have different physical properties?
Yes they do.
Which, cis or trans, have a dipole moment?
cis has a dipole moment, while trans does not.
Which has stronger intermolecular forces?
Cis has stronger forces due to the dipole moment.
What does stronger intermolecular forces pertaining to geometric isomers infer about their physical properties?
Cis molecules have higher boiling points
What does a lack of symmetry among cis molecules infer about their physical properties?
They are unable to form crystals as readily due to their lack of stackability
Which has higher heats of combustion due to steric hindrance?
Cis molecules have higher heats of combustion because they have higher energy levels due to steric hindrance
Do diastereomers have different physical properties?
They have different rotation of plane-polarized light, as well as different melting and boiling points as well as solubilities.
What is the maximum number of optically active isomers found via?
The equation is 2^n, where n is the number of chiral centers
What are meso compounds?
They are compounds where two chiral centers can offset eachother creating an optically inactive molecule
Are meso compounds achiral?
Why are meso compounds considered achiral?
Because they have an internal plane of symmetry
What are epimers?
They are diastereomers that differ at only one chiral carbon
What are anomers?
They are the two possible diastereomers that form during an epimeric ring closure.
What is the chiral carbon of an anomer called?
Anomeric carbon
When the hydroxyl group on the anomeric carbon on glucose is oriented in the opposite direction to the methyl group, what is the anomer labeled as?
What about when the hydroxyl group is in the same direction?
It is labeled beta.
What governs boiling point trends in alkanes?
Intermolecular forces
When carbons are added to a single chain alkane, the molecular weight goes up increases intermolecular forces concurrently. What happens to the boiling point?
It goes up.
What does branching do to boiling point in alkanes?
It lowers the boiling point
Does melting point go up or down in alkanes with increased molecular weight?
It goes up
What does branching due to melting point of alkanes?
It increases it
Are alkanes soluble in water?
What are alkanes soluble in?
They are solube in benzene, carbon tetrachloride, chloroform, and other hydrocarbons
If an alkane contains a polar functional group, what happens to the polarity of the entire molecule and its solubility as the carbon chain is lengthened?
It goes down
Do alkanes have low density?
What happens during combustion?
An alkane reacts with oxygen, producing CO2, H2O and most importantly heat
Is combustion spontaneous?
No, it requires heat to occur, usually via a flame.
What type of reaction is combustion?
It is a radical reaction
If a molecule has a high heat of combustion, is it more or less stable than a similar molecule with a smaller heat of combustion?
A high heat of combustion correlates to the energy level of a molecule, inferring a less stable molecule
What happens if you react an alkane with F, Cl, and Br in the presence of heat or light?
Well what happens first in halogenation?
The first step is initiation.
What happens during initiation?
Light or heat cleaves a covalent bond between a two bound halogens. They both split leaving two identical radicals
What happens to these radicals after that, and what is the step called?
The next step is called propagation, and what happens is the halogen radical removes a hydrogen from the alkane, resulting in an alkyl radical.
What can this alkyl radical do to get rid of its radicalness?
It can hookup with a diatomic halogen molecule creating an alkyl halide and a new halogen radical.
Is this the end of our halo-radicals?
No! This reaction can continue indefinately, or it can go through the third and final step of halogenation.
What the third and final step of halogenation?
So what exactly happens in the termination step of halogenation?
Several things could happen. Two akyl radicals could react, the last halo-radicals can react with alkyl-radicals to form alkyl halides, or two halo-radicals can hookup
Is halogenation an endothermic or exothermic process?
It is exothermic
What is the stability chart for an alkyl radical?
What type of geometry do alkyl radicals exhibit?
They exhibit trigonal planar geometry
When is the majority of product formed during halogenation?
The majority of the alkyl halides are formed during propagation
Are Pi-bonds more or less stable than Sigma-bonds?
They are less stable
Does this mean alkenes are more or less reactive than alkanes?
They are more reactive.
When dealing with alkenes, what should I keep in mind about the Pi-bonds?
They are electron hungry
What does this infer about acidity values of alkenes versus alkanes?
Alkenes are more acidic as a result of the willingness to gain electrons
What happens when a proton is moved away from a Pi-bond?
The Pi-bond of the alkene absorbs some of the negative charge
What does this do to the conjugate base?
It stabilizes it
How does substitution relate to thermodynamic stability of alkenes?
They more highly substituted, the more stable the alkene.
You're wrong! How come when you have addition reactions dealing with electrophiles the most substituted are the most reactive, it should be the opposite right?
Well a paradox exists due to the carbocation intermediate. A tertiary alkene will be a more stable carbocation, so it will proceed with greater frequency.
So which is right?
When dealing with electrophilic addition reactions of alkenes, the most reactive are the more substitituted
How do physical properties of alkenes work?
They work the same way as alkanes
Are alkenes soluble in water?
Slightly, and they have a lower density than water.
Which is more acidic, alkanes or alkenes?
What happens in an elimination reaction?
One or two functional groups are eliminated or removed to form a double bond.
What type of reaction is dehydration of an alcohol?
It is an E1 reaction
What happens in dehydration of alcohol reactions?
An alcohol forms an alkene in the presence of hot concentrated acid
Since it's an E1 reaction, that means it depends on the concentration of only one reactant, but which reactant does it depend on, the acid or the alcohol?
It depends on the concentration of the alcohol in this case.
What happens in the first step of dehydration of alcohols?
The acid protonates the hydroxyl group
What does this produce, and what was the purpose of protonating this new thing?
It produces water, which is a good leaving group. It wants to dump off the compound.
What happens next, and whats so special about this step?
This is the rate-determining step- the water drops off, forming a carbocation
Woo, carbocation. When I see carbocation I should think what?
Rearrangement possibilities exist, and stability of intermediate
What does carbocation stability follow the trend of?
It follows th same trend as radical stability?
What's that trend again?
So when would rearrangement occur?
It would only occur if a more stable carbocation could be made
What happens in the final step of dehydration of an alcohol?
A water molecule deprotonates the carbocation and the alkene is formed
What will the predominant product be a result of?
It will be the more stable, most substituted alkene.
What does the Saytzeff rule say?
It says that the major product of elimination will be the most substituted alkene.
What is dehydrohalogenation?
It's what happens when you take an alkane with a halogen and dump the halogen off in favor of making an alkene.
What are the two possibility routes for dehydrohalogenation to occur?
It can occur via E1 or E2
When would dehydrohalogenation occur via E1?
It would happen if a strong base is there
When would dehydrohalogenation occur via E2?
It would happen is there is a high concentration of a strong, bulky base
What happens first in the E1 reaction?
The halogen drops off in the first step.
What happens second in the E1 reaction?
The hydrogen is removed in the second step via the weak power of our weak base.
So the E1 reaction is multi-step or single-step?
What happens in E2 reaction?
The base removed a proton from the carbon next to the halogen-containing carbon and the halogen drops off, leaving an alkene.
So is the E2 reaction single or multi-step?
It is single step.
What does the bulky base of this E2 mechanism prevent?
It prevents an SN2 reaction, but if the base is too bulky, the Saytzeff rule is violated, leaving the least substituted alkene.
So what's an important thing to notice about the difference between these two pertaining to the power of the bases?
Well the E2 mechanism has a strong base, and it's so pimped out that it can pull the hydrogen off even without the decreased stability of an intermediate state like what occurs in the E1 mechanism.
What type of reaction of catalytic hydrogenation?
It is an addition reaction?
What type of catalyst is used in catalytic hydrogenation?
A heterogenous catalyst
What type of addition occurs usually?
What are possible catalysts?
Ni, Pd, or Pt
So what actually happens?
You take an alkene and you turn it into an alkane
Is hydrogenation an endothermic or exothermic reaction?
It is an exothermic reaction.
Is it spontaneous?
No, it has a high energy of activation
What are heats of hydrogenation used to measure?
They are used to measure the relative stabilities is alkenes.
If something has a low heat of hydrogenation, is it unstable?
No it is considered stable
What happens with syn addition of an alkynes via hydrogenation?
It creases a cis alkene.
What does oxidation of an alkene produce?
It may produce glycols or it may cleave the alkene at the double bond
What is an example of a cleavage such as this?
If you add 1) O3 and 2) Zn,H2O, what happens to an alkene?
It will cleave the alkene at the double bond, producing two carbonyl groups
What happens to alkynes when they undergo ozonolysis?
They produce carboxylic acids
What is an electrophile?
It is an electron-loving species
What types of things are usually electrophiles?
Things with a positive charge, even if it is only from a momentary dipole.
What does the double bond of alkene function as pertaining to electrophiles?
It is an electron-rich environment, which will attract electrophiles
What rule is followed when you had a hydrogen halide to an alkene?
Markovnikov's rule
What does Markovnikov's rule state?
It states the hydrogen will add to the least substituted carbon of the double bond
What is the first step of electrophilic additition of a hydrogen halide to an alkene?
The hydrogen halide is a Bronsted-Lowry acid, so it will create a positively charged proton, which acts as an electrophile.
What is the second step of electrophilic additition of a hydrogen halide to an alkene?
The newly formed carbocation picks up the negatively charged halide ion.
Which is the slow step?
The first step is the slow step, and it determines the rate
What happens during this reaction is peroxide (ROOR) is present?
Bromine will add to the least substituted carbon
What is this known as?
Anti-markovnikov addition.
Will the other halides perform anti-markovnikov addition?
No, they still do Markovnikov, even in the presence of ROOR.
What are the most reactive alkenes, and why?
The most reactive are the most thermodynamically stable, because they also have the lowest activation energy and form carbocations the easiest.
What is hydration of an alkene?
It takes place when water is added to an alkene in the presence of an acid.
Does hydration of an alkene follow Markovnikov's rule?
Yes it does.
What is this reaction the reverse of?
It is the reverse of dehydration of an alcohol.
What circumstances drive an alkene toward alcohol formation?
Low temperatures and dilute acid
What circumstances drive an alcohol toward alkene formation?
High temperatures and concentrated acid
What is oxymercuration/demercuration?
It is another reaction which creates an alcohol from an alkene
Is oxymercuration/demurcuration a one or two step process?
Two step process
Does it usually result in rearrangement of the carbocation?
Very rarely.
What happens in the first step of oxymercuration/demurcuration?
The mercury-containing reagent partially dissociates to +Hg(OAc)
What does the +Hg(OAc) do once its formed?
It acts as an electrophile creating a mercurinium ion
What does water do to the mercurinium ion?
It attacks the mercurinium ion to form the organomercurial alcohol.
What type of addition is this?
What is the second step?
It is the demercuration to form the alcohol
How is this performed?
By the addition of a reducing agent and base.
What is hydroboration?
It is another mechanism to produce an alcohol from an alkene
Does it follow Markovnikov?
No, it is anti-markovnikov
What type of addition is it?
It is syn addition
So what happens in hydroboration?
Take an alkene and add a hydrogen and alcohol to the same side of two carbons, via anti-markovnikov.
What happens if you add Br2 or Cl2 to an alkene?
They add via anti-addition to form vicinal dihalides
What is an important difference between a similar reaction involving alkanes?
Oh, you mean halogenation, right? Well alkene halogenation doesn't require heat or light
What happens if you perform alkene halogenation in the presence of water?
Water will act as a nucleophile instead of a bromide/chloride ion.
What does this produce?
It produces an anti-addition halohydrin
Does benzene undergo addition or substition?
It only undergoes substitution
Is benzene flat?
Yes, it has to be considering its aromatic
What happens when an electron withdrawing group is in the R position of a benzene?
It deactivates the ring and directs any new substituents to the meta position
What do electron donating groups do to the wring?
They active the ring and direct any new substituents to the ortho and para positions.
What is the exception to this rule, and why?
Halogens are an exception because they are electron withdrawing and deactivate the ring as expected but they are ortho-para directors.
What are the strongly electron donating groups?
What are the moderately electron donating groups?
What are the weakly donating groups?
What are strongly electron withdrawing groups?
What are moderately withdrawing electron groups?
What are weakly withdrawing electron groups?
What is phenol?
It is a benzene with an alcohol substituent.
What is aniline?
It is a benzene with an amino substituent.
What is toluene?
It is a benzene with a methyl substituent..
What is benzoic acid?
It is a benzene with a carboxylic acid
What is nitrobenzene?
It is a benzene with a nitro group.
What happens in a substitution reaction?
One functional group replaces another.
How many steps does an Sn1 reaction have?
2 Steps
What is the rate of an Sn1 reaction dependent on?
The rate is dependent on one of the reactants
Is this the fast step?
No, it is the slow step.
Does this make it the rate determining step?
Yes it does.
Does the creation of a carbocation depend on the nucleophile?
Nope, because it attacks during the second step after the carbocation has been made.
So what does the rate of an Sn1 reaction depend on then?
It only depends on the concentration of the substrate.
What is the leaving group?
It is the group being replaced.
What happens if you perform an Sn1 reaction creating a carbocation from a chiral carbon?
You would get two products, both enantiomers of eachother other.
Why will both enantiomers be made?
They will both be made because the intermediate carbocation is planar, which allows the nucleophile to attack from both sides.
Can carbon skeleton rearrangement occur in an Sn1 reaction, and if so, under what circumstances?
It can occur if rearrangement produces a more stable form.
How can an E1 reaction accompany an Sn1 reaction?
It can because the nucleophile may act as a base to abstract a proton from the carbocation, forming a carbon-carbon double bond.
What type of substrate will most likely undergo an Sn1 reaction?
A more substituted substrate will because the carbocation produced will thus be more stable due to increased branching.
How many steps does an Sn2 reaction take place in?
1 step
What is the rate of an Sn2 reaction dependent on?
It is dependent on the concentration of both substrate and nucleophile.
What is the substrate in these reactions?
It is the electrophile or the molecule being attacked by the nucleophile.
How does the nucleophile attack the intact substrate in an Sn2 reaction?
It attacks it from behind the leaving group.
What does this cause as a result?
It causes an inversion of configuration
What type of substrate will hinder an Sn2 reaction, and why?
A more substituted substrate would hinder the reaction because the nucleophile wouldn't be able to attack from the rear as easily due to steric hindrance.
What could occur instead of an Sn2 reaction if the nucleophile is a strong base and substrate is very hindered?
An E2 reaction could occur
What happens in an E2 reaction?
The nucleophile acts as a base abstracting a proton and, in the same step, the halogen leaves the substrate forming a carbon-carbon double bond.
What else is another hindering factor when dealing with Sn2 reaction when pertaining to size of interacting molecules?
If the nucleophile is too bulky, the Sn2 reaction could be hindered.
Is a base a weaker or stronger nucleophile than its conjugate acid?
It is always a stronger nucleophile than its conjugate acid.
Well what determines if a substitution or elimination reaction will occur based upon basicity?
If a nucleophile behaves as a base, elimination results.
So how can we avoid an elimination reaction from occuring pertaining to nucleophiles if we want a substitution reaction take place?
Just use a less bulky nucleophile.
What do negative charge and polarizability do to nucleophilicity?
They add to it, increasing the likelyhood of electron donation.
What is the general trend concerning electronegativity dealing with nucleophilicity?
Electronegativity generally reduces nucleophilicity when going up and to the right on the periodic table
What are polar protic solvents?
They are solvents that can hydrogen bond.
What do polar protic solvents do to nucleophiles?
They stabilize them.
What do polar protic solvents do to carbocations?
They stabilize them.
Does a stable nucleophile speed or slow an Sn2 reaction?
It slows an Sn2 reaction down.
Does a stable carbocation increase or decrease the rate of Sn1 reactions?
It increases the rate of Sn1 reactions
So what's the takeaway for polar protic solvents concerning Sn1 and Sn2 reaction rates?
They increase Sn1 rate and decrease Sn2 rate.
What are polar aprotic solvents?
They can't hydrogen bond
Do they form strong or weak bonds with ions?
They form strong bonds with ions
What does this do to Sn1 and Sn2 reactions?
It increases the rate of Sn2 reactions while inhibiting Sn1 reactions
What would be the purpose of heating a solvent in substitution reactions?
This is sometimes done in Sn1 reactions in order to provide energy for the formation of the carbocation.
What is solvolysis?
The solvent acts as the nucleophile
What are the best leaving groups?
They best are those that are the most stable when they leave.
Generally speaking, how does the strength of the base determine leaving group stability?
Generally, the weaker the base, the better the leaving group.
How does electron withdrawing ability effect leaving group ability?
Generally, electron withdrawing groups are good leaving groups.
Is the leaving group going to be stronger or weaker than the nucleophile?
It will always be mor estable than the nucleophile
What type of physical trends to alcohol's follow?
They follow the same basic trends as alkanes.
What are those trends again?
The boiling point goes up with molecular weight and down with branching. The melting point also goes up with molecular weight.
Why are alcohol melting and boiling points much higher than alkanes?
They hydrogen bond, which increases intermolecular forces, which must be overcome to change phase.
Is a longer carbon-chain alcohol more or less soluble in water than a short carbon chain alcohol?
It is less soluble in water.
Are alcohol's more or less acidic than water?
They are more acidic than water.
What is the order of acidity for alcohols?
Why would increased substitution cause less acidity?
The more substituted, the stronger the oxygen and hydrogen bonds, due to the electron donating effects of carbons.
Is excess charge a stability or instability?
It is an instability.
So how does this relate to carbonds and alcohols?
The most stable conjugate base will have the weakest negative charge, and since carbons donate electrons, they increase the charge of the oxygen and alcohol inductively, effectively decreasing the stability of the conjugate base.
What can you do with an organometallic compound pertaining to alcohols?
You can synthesize an alcohol with one.
What do organometallic reagents possess?
They possess highly polarized carbon-metal bonds.
Which is more electronegative of the two bonds?
The carbon is more electronegative than the metal.
So which will be partially negatively charged?
The carbon will take a partial negative charge.
What does this make the organometallic reagent?
It makes it a strong nucleophile and base.
What is the most common organometallic reaction?
Nucleophilic attack on a carbonyl carbon.
This produces an alcohol after what type of bath?
An acid bath
What are the reagents known as?
Grignard reagents
What else do Grignard reagents react with?
They also react with C=N, NItrile, S=O, N=O.
What is the Grignard reagent a strong enough base to deprotonate?
It can deprotonate O-H, N-H, S-H, and an alkyne hydrogen.
What do Grignards require to form?
What happens if yuo add NaBH4 or LiAlH4 to a carbonyl?
In a mechanism similar to Grignard synthesis, a hydride reacts with carbonyls to form alcohols
What can be used to reduce aldehydes and ketones to alcohols via this method?
Both NaBH4 and LiAlH4 can be used.
What can be used to reduce esters and acetates to alcohols?
Only LiAlH4 is strong enough.
Why is it more difficult to reduce esters and acetates than ketones and aldehydes?
The group attached to the carbonyl of the ester or acetate is a stronger electron donor than an alkyl group or hydrogen
What does donating electrons more strongly have to do with reduction synthesis of an alcohol?
Well if something next to the carbonyl donates electrons more strongly, it will reduce the positive charge on the carbonyl carbon making it less attractive to the nucleophile
Most of the time on the MCAT, if an alcohol is a reactant what will be it be acting as?
A nucleophile
What do the two lone pairs of electrons on the oxygen do?
THey are pushed out by the bent shape, and they search for a positive charge.
What does this cause the oxygen to do?
It makes it want to find and connect to the substrate and the positively charged proton will drop off into solution.
What happens if an alcohol as a nucleophile attacks a double bonded substrate?
It can do a nucleophilic addition, just adding to the double bond making it a single bond.
What happens if an alcohol as a nucleophile attacks a single bonded substrate?
It will do a nucleophilic substitution.

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