If the pKa is larger than the pH are most of the protonated amino groups going to be deprotonated? (No. The equilibrium will shift to the acidic side, that is the protonated form. - GS).

Dr. Sereda, in order to separate a mixture containing a hydrocarbon and an amine, I am thinking you would first want to dissolve the mixture in diethyl ether since they are both soluble in this, transfer this into a separatory funnel, and then add a strong acid which will react with the amine, converting it into an ammonium salt which is soluble in water. So then in the separatory funnel, the organic layer would include the hydrocarbon component and the aqueous layer would include the amine. (The aqueous layer will contain the ammonium salt. - GS).  Is this method correct? (Yes, but not complete. Now you need to get your amine back. - GS).

Is decarboxylation the loss of a carboxy-group in the form of carbon dioxide? (Yes. - GS).

Is it correct to think that diethyl ether will not form a carboxylic acid upon acidic hydrolysis since it does not contain a carbonyl group? (Yes. - GS).

For increasing reactivity of carboxylic acid derivatives in nucleophilic acyl substitution, the order of reactivity goes nitriles<amides<esters and acids<anhydrides< acid chlorides, right? (Almost. Remove the acid from the row, because it forms a salt instead of undergoing acyl substitution. - GS). If so, is that the same reactivity for hydrolysis? (Yes. - GS). Thank you!

Esters make good soaps, right? (Not necessarily. - GS). To look for a soap, do you want to find something that has a long hydrocarbon tail with a polar end? (Yes, and the polar end should better be ionized. - GS).

For the “rule” that weak bases make good leaving groups, does that apply to every type of substitution  reaction? Or just certain ones? (For all reactions when the leaving group leaves with accepting an electron pair. - GS).

amides are more acidic than amines due to the conjugation of the electron pair with the carbonyl group, right? (Yes, because this conjugation is stronger in the conjugate base. - GS).

Is hydrolysis of esters the backwards reaction of Fischer esterification? (Only under acidic conditions. - GS).

Dr. Sereda, Im a little lost on the reaction of anhydrides part, I know you covered it in class today, but could you maybe skim over it again please? (The leaving group is acetate, and the reaction does not produce a strong acid, so does not require an external amine to neutralize it. For cyclic anhydrides, the flavor of the reaction is that the “leaving group” leaves the reaction center, but stays a part of the molecule, to which it is tethered. - GS).

Why are amides less basic than amines? Is it because of the lone electron pair on nitrogen? (No. Because the lone electron pair on nitrogen is deactivated by conjugation with the carbonyl group. - GS).

I’m confused as to why cyclopentadiene is more reactive than trans,trans-2,4-hexadiene and cis, cis-2,4-hexadiene. Is it because of the s-cis conformation? Thanks. (Because cyclopentadiene is locked in the s-cis conformation. - GS).

How would you decide which molecule is more reactive between ethyl acetate and sodium acetate for nucleophilic acid substitution? Ethyl acetate is much more active than sodium acetate, because ethoxide is a weaker base than O2- - GS).

Could you explain why the carbonyl group of ethyl acetate is more stable than that of ethyl thioacetate? (The carbonyl group is more stabilized in esters, because the lone electron pair on oxygen (period 2) better fits by size to the pi-system of the C=O group ((period 2) than the lone electron pair on sulfur does (period 3).  

Dr. Sereda, for an ozonolysis reaction, can the reactant have two double bonds in its structure? And if so, how would the reaction proceed? Like which double bond would go through the reaction? (Yes. Multiple C=C bonds react independently, and the compound may split to more than two pieces. - GS).

Can you explain what an enolate ion is? (Conjugate base related to abstraction of the alpha-proton. - GS).

Dr. Sereda, what exactly is an alpha hydrogen? (Hydrogen bonded with the carbon next to carbonyl. - GS). and how do you determine the acidity of it? (Standard approach: mostly look at the stability if the conjugate base. - GS).

Being more sterically hindered makes a molecule more reactive, correct? (Steric hindrance increases potential energy. To connect it with reactivity, this change must be monitored through the whole potential energy diagram. - GS).

So an aldehyde is when the C in the carbonyl group is connected to a CH3 group and an H? (H and C or two H are bonded with the carbonyl. - GS). And a ketone is when that H is something else right? (Two carbons are bonded with the carbonyl. - GS). So the difference (in structure) between them would be just that one “R” group? (Presence of H makes the difference. - GS).

How do I figure out what the starting materials for the ozonolysis are? (To figure out the ozonolysis products, completely break C=C bonds, and attach oxygens to the pieces. To go back to the starting materials, do the opposite. - GS). Thank you

If you are comparing two compounds with only primary amines, and one compound has more primary amines than the other, would the one with more have a higher boiling point? (True, if there are no groups that make H-bonds stronger than amino-groups (e.g. alcohols, carboxylic acids. - GS). If so, would this have to do not only with hydrogen bonds, but also van der waals forces? (Van der Waals forces are negligible compared with H-bonds,- GS).

How do you distinguish the basicity levels for amines? Like what makes an amine a weaker/stronger base? And why? (The more the lone electron pair of N is involved in conjugation, the less basic it is. Also, sp2-hybridized nitrogen is less basic than sp3-hybridized nitrogen, because the lone pair has lower energy and, therefore, less reactive. - GS).

Weak base = better leaving group for sn1 and sn2? (Yes. Also for E1 and E2 - GS).

Does protonation create a better leaving group? (Yes for alcohols. - GS).

Resonance structures provide a means to show electron delocalization which in turn stabilizes the structure, right? (Yes. - GS). So for simplicity’s sake this means that structures that can be demonstrated using resonance structures for it are more stable than a similar molecule that cant form resonance, right? (Correct. - GS).

^^Could you explain why electron delocalization would be seen as stabilizing if a carbocation or anion would constantly result from this formation? (Electrons will have more space and more opportunities to lower their energy. Same on the math language: there will be more coefficients to optimize in the linear combination of atomic orbitals - GS). Wouldn't a neutral structure with no charged carbons be more stable than one that would observe resonance characteristics?  (The neutral structure will be most contributing. - GS).

How do you know which reaction product is less stable? For example, in the addition of HCl to conjugated dienes, the major product formed is 1,2-addition results in major product which is less stable than 1,4-addition. Is 1,4- just typically more stable? (Yes, because of a more substituted C=C bond - GS).

How do you determine the rate limiting step in a reaction that consists of multiple steps (with no fore knowledge (It is impossible. That what that knowledge is for. - GS). of rate speeds/ no diagram)? Is it simply the first step? (No. It is the step with the lowest activation energy. - GS).

What makes CH3 an electron donor when it is bonded to benzene? (sigma-pi conjugation. - GS).

^^ can you please explain how to tell when a sigma and pi orbital overlap? (When they are at carbons next to one another and are aligned - GS).

Is dehydration considered an elimination reaction? (Yes for alcohols. - GS).

When determining ortho-para or meta directors, do you look at the substituent that is already attached to the ring (Yes. - GS). or at the substituent being added? (No. - GS).

Can a benzyl group technically also be considered as a phenyl group? (I know that a phenyl expands from just a benzyl but was wondering if it was correct to think that a benzyl could potentially be a phenyl as well? Thanks (No. They are different groups. - GS).

Can catechol also be called ortho-hydroxyphenol? resorcinol = meta? and hydroquione = para? (Yes. - GS).

Do both E1 and SN1 reactions proceed through a carbocation? (Yes. - GS).

What’s the difference between an epimer and a diastereomer? I have written in my notes that configuration of only one center is opposite for both of them. Thanks. (Epimers are different by the configuration of one chiral center. They can be diastereomers. - GS).

Generally speaking, if an atom has high nucleophilicity, does that make it a bad leaving group? (No. High basicity does. - GS).

So, great leaving groups would be those that are weak bases correct? (Yes. - GS). That strong acids would be the best leaving groups (once they are deprotonated?) (No. Conjugate bases of strong acids are good leaving groups. - GS).

Can you explain the properties and reactivity of antioxidants? (They intercept reactive free radicals. - GS).

Does elimination always form a double bond? (No. E1 - yes. E2- either double or triple bond. - GS).

are electron donors always ortho-para, because they are more stable due to resonance structures? (Donors always preferentially stabilize intermediates leading to products of ortho- and para- substitution. - GS).

What is the difference between CH3 and alkyl? (Methyl is an example of alkyl - GS).

Are halogens inductive acceptors and resonance donors? (Yes, but Cl, Br, and I are also resonance acceptors because of the empty d-orbitals - GS). So, are halogens resonance donors and resonance acceptors? (No. They are resonance donors and inductive acceptors. Cl, Br, and I are also resonance acceptors because of the empty d-orbitals - GS).

How many steps does the electrophilic substitution (SeAr) have? (Three. - GS). What are the names of 1st and 3rd steps? Is third dehydrogenation of the pi complex? (Step 1- pi-complex; Step 2 - sigma-complex (rate limiting); Step 3 - deprotonation. - GS).

What directs the position of substituents? The substituent on the benzene ring prior to the reaction? Or the electrophiles? (The existing substituent before substitution. - GS).

Would you mind explaining why ethanol for gasoline is so effective at functioning as a “fuel”? (Ethanol increases resistance of fuel to premature ignition (increases octane rating) by intercepting free radicals, but decreases the energy content of fuel (mileage) - GS).

Could you explain how DDT work as pesticides? (By opening sodium channels and, therefore, disrupting nerve impulses. - GS).

Why would a compound that mimics a plant growth hormone be used as a commercial lawn fertilizer?  Wouldn't that just cause the plant to grow more quickly? (Yes, it is not a nutrient. In larger concentrations, they are used as herbicides, because they make the plant grow so unnaturally fast, that the plant dies quickly. - GS).

Brominated organic molecules are used commercially as flame retardants, why is that? (I thinks that the three following contributors are important: 1. Br-containing molecules act as traps for free radicals, so they speed up free radical chain termination; 2. Non-combustible molecules (HBr and Br2) are produced, and they extinguish fire like carbon dioxide; 3. Bromine does not bond well with oxygen, so the energy spend on breakage of the C-Br and C-H is not compensated enough by a relatively weak H-Br bond. - GS).

The flammability is due to its ability to oxidize in addition to its high energy, right? so what makes a molecule more capable of oxidizing?  (This is a good factor, but it is also important how well the compound mixes with oxygen, and how well a free-radical chain reaction sustains. - GS).

Why doesn’t free radical halogenation with iodine occur ? (The H-I bond is too weak to make up for the broken C-H bond. - GS). Why is free radical halogenation violent when it occurs with fluorine? (The H-F bond is very strong and releases energy that rips apart the molecule. - GS).

Alcohols are a weak acid, which is why we can intake alcohol without experiencing severe irritation, right? (Ethanol causes irritation when its concentration exceeds 40%, which corresponds to the hydrate of ethanol. Above this concentration, ethanol acts as a drying agent. It was a part of M.S. thesis of Dmitri Mendeleev, which is much less known than his periodic table of elements.  - GS). But just out of curiosity is the fact that alcohol is indeed a acid (even though its weak) one of the reasons alcoholics experience extreme symptoms such as ulcers (which could be described as an erosion or “break” of intestinal lining, etc.)? Is that alright to observe those effects in that manner, or is that side effect due to a different characteristic altogether? (No. Those adverse reactions are mostly because of oxidation of ethanol to a toxic ethanal. - GS).

So is it wrong to think that more polar molecules often have lower boiling points if the molecular size is similar? (Polar molecules have higher boiling points because of stronger electrostatic intermolecular interaction. - GS).  Larger molecules have higher boiling points? (Yes, because of stronger Van-der-Waals intermolecular interaction. - GS).

Could you go over how the free radicals one more time? I still don’t fully understand it. Thanks (Ok. Please, also review this: http://ochem.orgfree.com/SR.html  - GS).

Hi Dr. Sereda, I was wondering if you could explain a little better the relationships with the boiling points, polarity, molecular size, and molecular shape? (Molecular shape determines polarity. Polarity and molecular size, and again shape, determine intermolecular interactions. Intermolecular interactions determine the boiling points. - GS).

Is a rearrangement reaction going to take place when the conditions are in line with a SN1 reaction? Because a rearrangement reaction is where a carbocation gets reformed into something more stable and in an SN1 reaction is where one of the steps to get to the product is through a carbocation intermediate. (Yes. SN1 and any other reaction involving carbocations can be complicated by carbocation rearrangements. - GS).

Dr. Sereda would you mind explaining how we differentiate between SN1 (http://ochem.orgfree.com/sn1.html  - GS) and SN2 (http://ochem.orgfree.com/sn2.html  - GS). reactions? (See the links that I inserted to your question. - GS).

There is not a big difference between E1 and Sn1 reactions, as it is in E2 and Sn2? If there is one, could you explain? (Elimination requires a base and produces a C=C bond, substitution requires a nucleophile and does not produce a C=C bond. - GS).

Dr. Sereda, could you please remind me how I find E2 reactivity when working with halides? Thank you (A better leaving group, stronger base, and the most substituted C=C in the product will increase E2 reactivity. - GS).

If you double both concentrations of the reactants in an SN2 reaction, does that mean that the reaction rate will increase by 4? (Yes, which proves that it is a second order reaction (22=4). - GS).

Would a hydrogen be most readily substituted with a Br from a carbon that has the least number of H (according to Zaitsev’s rule)? (Yes, but not because of Zaiysev’s rule. That will be free-radical bromination. - GS).

What kind of effect does an Sn2 reaction have on the product? (If this reaction occurs at a chiral center, its configuration flips. - GS).

Is a glycol still considered an alcohol? (Yes. - GS).

Are fischer projections strictly for chiral carbons/centers? (No. They are for looking across any chemical bond in an eclipsed conformation from behind. - GS).

Different compounds can be expressed in terms of optically pure compounds as (+) or (-), could you explain how we are supposed to differentiate between when its (+) or negative? Is it simply in regards to the rotation it expresses so it has a negative then it would be because it is the enantiomer of the optical compound? (If a compound has positive rotation, its enantiomer will be for sure negative, and vice versa. You cannot determine an absolute value or sign of rotation just by the structure. An experiment is needed. - GS).

^^Sorry this may be naive, but what do we gain by knowing if its (+) and (-)? (It is part of a compound’s identity and purity, like its melting point. - GS).

^So you could use it as another way to identify a compound? (Yes, and evaluate its purity, which also embraces monitoring chemical reactions of that compound. Mutarotation is a great example. - GS).

Newman projections are only for alkanes, right? (No. They are for looking along any chemical bond. - GS).

how does a racemate relate to a meso compound? I am confused where this would fit into their nice flowchart that they have given to us in the text. (Racemate is a mixture, meso-compound is one compound. Components of a racemic mixture are enantiomers. - GS).

I am not fully understanding the idea of the meso compounds. I read the book and have an idea, but I was wondering if you could go over that again in class in better detail? thanks! (Meso-compounds are achiral compounds with chiral centers. - GS).

I dont understand how a molecule can be a mirror image but not be congruent? IS there any way you could draw an example of this, if it is even possible? Thanks (Your hands or feet are excellent examples of such objects. - GS).

Is an asymmetric carbon and a chiral carbon the same thing? (Yes. - GS).

^^or an asymmetric carbon and a chiral center? (No. Not only carbons can be chiral centers. - GS).

Why does a book describe a hand as being chiral? I get why its an enantiomer but why chiral? (Because it is different from its mirror image. - GS).

If a 2 compounds are congruent does that make them identical? (Yes. That is another word for this. - GS).

How do you determine how many chiral centers there are??? (Pick atoms with 4 different substituents, and count them. - GS).

why is the sigma bond in a double bond sp^2-sp^2, and the triple bond sp-sp? (Because in the first case, geometry at carbon is trigonal planar, and in the second case - linear. - GS).

For a dehydration reaction, how do you know which carbons in the molecule will form the double bond? (The carbon bearing the OH-group, and the next carbon. - GS).

For thermal cracking, simply stated, the process is essentially flash heating (It will work. - GS) and then rapidly cooling the substance so that the compound separates? (No. It is to prevent further decomposition to carbon. To separate, distillation must follow. - GS).

Dr. Sereda, can you explain why sometimes the cis-trans terminology fails to describe certain stereoisomers? (Because sometimes you do not know at which substituents to look, so you need rules for prioritizing them, which is E-Z- nomenclature. - GS).

The relative density of a polymer is due to branching factors mainly, right? So would it be correct to assume that thicker materials such as thick plastic sheets (for example) would be due to a polymer that is less branched (aks more “linear” of a structure) (Yes. - GS). whereas the plastic for packaging is more branched making it more flexible? (Flexibility is mostly determined by conformational mobility. - GS). Just out of curiosity, how would you go about manipulating this concept, so that you could produce a compound of desired density? (In industry, radical-induced polymerization of ethylene causes the radical centers hopping along the chain, which causes branching. Polymerization directed by a metal (Ziegler-Natta catalyst), produces mostly linear chains. An extreme example of this type of manipulation is making aerogels in supercritical carbon dioxide. - GS). Meaning if I were to say add heat to the compound/ substance the material would become more flexible? (Yes, which is why under freezing temperatures, some plastics and rubbers become inflexible, fragile, and may fall apart. It is a big issue for aircraft landing gear and spaceships. - GS).

Rate limiting step is that determined by the step with the highest Transition state only or is it the largest difference between the minima (intermediate) and the transition state that determines the rate limiting step? (The difference between the transition state and the preceding intermediate or starting material determines the activation energy and, therefore, the reaction rate. - GS).

Am I correct in thinking that alkenes are the only compounds that can be labeled cis or trans since alkanes can rotate around the single C-C bond and alkynes can only bind to one other substituent on either side?  (No. Cyclic compounds also can be cis- or trans- - GS).

Did you say that trans is typically more stable than cis ? (Yes, if there is no attraction between the substituents. - GS). if so would the same apply for Z configuration in terms of it being more stable than E? Thanks (There is no trend. It all depends on the repulsion and attraction between specific substituents. - GS).

When determining the strength of bases does the double and triple bond making the base stronger or weaker than a base with a single bond? Thank you (It make the base weaker due to a lowering energy as we go from sp3 to sp-hybrid orbital. - GS).

Would the acid base formula usually go Base + Acid → X? (It is typical for Lewis acids and bases - GS). And it would always go Base + Acid ←→ Acid + Base? (It is typical for Bronsted acids and bases. - GS).

Just to make sure I am understanding this correctly the curved arrow notation provides info on Redistribution of electrons and charges between the nuclei, right? (Yes, you are right on target. - GS).

Most of an acid is ionized when pH is larger than pKa, so would practically none of the acid be ionized if the pka was larger than the pH? And then about half would be ionized when the pH and the pKa are roughly equal? (Correct. - GS).

Would be correct to affirm that a ph-7.4 is half ionized? (Yes for acids with pKa = 7.4 - GS) To be half-ionized shouldnt be a ph=7? (Yes for acids with pKa = 7 - GS).

Would NH3+ be the conjugate base to H3O+ (the acid) in this example because H3O+ donates a H+ to produce NH3+? (No. H2O is the conjugate base to H3O+, because when H3O+, loses H+, it becomes H2O. The other pair is NH3 / NH4+ - GS).

I thought amines were classified as basic? (They can be both basic because of the lone electron pair, and acidic because of the N-H bond. It is called “amphoteric. - GS).

Could you go over principal chain once more? (For alkanes, it is the longest carbon chain with the largest number of substituents. - GS).

Would you say that 2,2-dimethylpropane only has primary hydrogens? (Yes. - GS).

I know that angular strain decreases stability, and that a larger ring decreases the effects of angular strain, so in general a larger cyclic ring would be more stable but how would trans and cis play an effect? Would you still consider a larger ring to be more stable even if trans were involved in a slightly smaller ring? (Stability of cycles sharply goes up from 3- to 6-membered ring, then slightly decreases and remains virtually flat. Trans- is usually more stable than cis-, however, conformational analysis should be performed on a case-by-case basis. Except for the textbook-easy conformational analysis of cyclohexane, for larger cycles it is really convoluted and requires full-blown computational research. The good news is that overwhelming majority of useful cyclic compounds have 6-membered rings!  - GS).

For angular strain is that limited to cyclic chains? (Most often - yes. However, it may show up in noncyclic compounds if you stick too many substituents to a limited space. - GS).