(quite a few) O/G Chem Concepts from Destroyer!

[TXpredent]

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Hi yall,

After 2 days of running through the Destroyer I found some things I'm confused on, particularly with the Chemistries. I'm not posting the exact question but questions regarding the concepts that I discovered I didn't understand. I may have even gotten the question right but if they added other answer choices in there I wouldn't know what to do. You'll see what I mean.

Before I get started, what the hell do yall do with the Roadmaps? Is there any order to them? It just seems like random reactions coming from one starting material. How does that help yall learn the reactions?

1) What special properties does a carbon (or that carbon's hydrogens) that's alpha to two carbonyl carbons? I think with heat something degrades? Are those hydrogens acidic?

2) How do allylic radicals rank with the substituted radicals? Are they more stable than tertiary radicals?

3) p-nitroaniline vs o-nitroaniline, how come the para isomer crystallizes but not the ortho isomer? How do EDG and EWG affect cystallization?

4) Regarding chair conformations of cyclohexane, the infamous Br vs CH3. Which one gets the equatorial position? Destroyer says CH3, Chad says Br.

5) How do we know the physical states of certain compounds? ie. Cl2, K, W, Pb, Hg, Br2, Sb. Which ones would be liquids at room temp, etc?

6) Regarding the acidity of H's, can someone explain the trend between a H attached to an sp C, phenolic H, carboxylic H, and an aldehyde H? I know it has something to do with stability of the conjugate base but I can't seem to figure out which one would be more stable out of those.

7) With 3-methyl-2-butanone, there's 2 methy type carbons attached to carbon 3 (one's part of the skeleton), how come under CNMR, it shows up as a different peak? Shouldnt they be equivalent? They're both bonded to an alpha carbon.

8) When a ketone tautomerizes into the enol form (in acid), how come that alpha carbon acts like a nucleophile?

9) I thought molecules were polar if they had dipole-dipole interactions or hydrogen bonding, but I think it has something to do with the lone pairs on the central atom? Can someone explain that? (Gen Chem question)

10) Biology question: why does the turn over of nutrients occur in ponds/lakes from summer to spring/autumn?

11) Bio question: Endospores should inhibit proliferation too right? I always thought of an endospore as a bacteria hibernating bc conditions are bad. They typically stop proliferating and start saving up energy, or so I thought. Destroyer says that "endospore inhibits proliferation" is false.

Sorry for all the questions, I figured this could help any of yall studying right now anyways to kinda test yourself on some concepts. Thanks again for all your help!

PS - put the number of the question you're answering next to the answer! Once it's answered, I'll bold it or change the color or something on the original post so people will know which ones to answer without having to scroll.

 

[mknara]

Hi yall,

After 2 days of running through the Destroyer I found some things I'm confused on, particularly with the Chemistries. I'm not posting the exact question but questions regarding the concepts that I discovered I didn't understand. I may have even gotten the question right but if they added other answer choices in there I wouldn't know what to do. You'll see what I mean.

Before I get started, what the hell do yall do with the Roadmaps? Is there any order to them? It just seems like random reactions coming from one starting material. How does that help yall learn the reactions?

1) What special properties does a carbon (or that carbon's hydrogens) that's alpha to two carbonyl carbons? I think with heat something degrades? Are those hydrogens acidic?

2) How do allylic radicals rank with the substituted radicals? Are they more stable than tertiary radicals?

3) p-nitroaniline vs o-nitroaniline, how come the para isomer crystallizes but not the ortho isomer? How do EDG and EWG affect cystallization?

4) Regarding chair conformations of cyclohexane, the infamous Br vs CH3. Which one gets the equatorial position? Destroyer says CH3, Chad says Br.

5) How do we know the physical states of certain compounds? ie. Cl2, K, W, Pb, Hg, Br2, Sb. Which ones would be liquids at room temp, etc?

6) Regarding the acidity of H's, can someone explain the trend between a H attached to an sp C, phenolic H, carboxylic H, and an aldehyde H? I know it has something to do with stability of the conjugate base but I can't seem to figure out which one would be more stable out of those.

7) With 3-methyl-2-butanone, there's 2 methy type carbons attached to carbon 3 (one's part of the skeleton), how come under CNMR, it shows up as a different peak? Shouldnt they be equivalent? They're both bonded to an alpha carbon.

8) When a ketone tautomerizes into the enol form (in acid), how come that alpha carbon acts like a nucleophile?

9) I thought molecules were polar if they had dipole-dipole interactions or hydrogen bonding, but I think it has something to do with the lone pairs on the central atom? Can someone explain that? (Gen Chem question)

10) Biology question: why does the turn over of nutrients occur in ponds/lakes from summer to spring/autumn?

11) Bio question: Endospores should inhibit proliferation too right? I always thought of an endospore as a bacteria hibernating bc conditions are bad. They typically stop proliferating and start saving up energy, or so I thought. Destroyer says that "endospore inhibits proliferation" is false.

Sorry for all the questions, I figured this could help any of yall studying right now anyways to kinda test yourself on some concepts. Thanks again for all your help!

PS - put the number of the question you're answering next to the answer! Once it's answered, I'll bold it or change the color or something on the original post so people will know which ones to answer without having to scroll.

(1) the C-H in between the two carbonyls are acidic. More acidic than water; pKa(water) ~16 and pKa(C-H with two carbonyls) ~10. This is generally true for other electron withdrawing groups other than the carbonyls as well.

(2) yes allylic radicals are more stable than tertiary

(3) I don't know what the point of the question was, but if the question was asking how to separate the two isomers, then all you need to recognize would be that structural isomers have different crystallizing properties. Usually, crystallization doesn't have to do with the electron withdrawing property and both para and ortho nitroanilines have the same properties when it comes to the electron withdrawing

(4) well if they are saying different things.... I think Me should be equatorial but don't quote me on that.

(5) You could know the general trends such as increasing mass of the molecule having bigger london dispersion forces resulting in higher boiling point (in noble gases/di-halides where dipole-dipole or hydrogen bonding is absent). But to know which compound is in what state for sure, you'd have to memorize..

(6)Out of the four, carboxylic H is the most acidic due to resonance stabilization of the resulting negative charge on to both oxygens. Then phenol O-H (pKa ~10) due to resonance stabilization onto the benzene ring, then sp C (pKa~25), which has to do with hybridization of the orbitals (sp3 is the least acidic, then sp2, and sp the most acidic). An aldehyde H is not acidic at all; in fact, if there is any alpha H, then that would be more acidic than the aldehyde H, because while the negative charge from deprotonating the aldehyde H cannot do resonance stabilization, the negative charge from deprotonation of alpha H can be resonance stabilized to C=O.

(7)Both methyl C's should be equivalent and show up as a single peak.

(8) When you draw the resonance structure of the enol, the alpha carbon will have a negative charge in one of the resonance structure. This gives a partial negative (and thus nucleophilic) character to the alpha C.

(9) When the molecule is made up of two kinds of atoms (with one central atom and the rest being the same atom), the molecule may or may not be polar. For example, CCl4 has polar bonds between C-Cl, but the molecule itself is not polar, because the dipole moment of the each bond is equal and opposite and they cancel each other out. But if the central atom has one or more lone pairs (such as Xe), the dipole moment of each bond does not cancel out any more (because lone pair is residing in one or more of the orbitals), and thus the molecule is going to be polar.

I'll leave the bio quesitons to others..

 

[Dotoday]

You did the right thing by writing down the topics you are confused about. See Destroyer, Achiever, topscore, crack the dat, are all great books, but they were designed for a review, not to learn the material from scratch. I would suggest, go to your chem textbooks and read up on each topic you are confused about, or post specific questions on the topics here in SDN. That is the best and most effective way to study. Good luck.

Sent from my MB855 using Tapatalk

 

[biomolecmed]

Carbocation stability and radical stability is very much like. The more substituted it is, the more stable it is. For example, if the most substituted carbocation in your question is secondary allylic, then it will be the most stable in that problem. In general tertiary benzyllic are among the most stable carbocations.

 

[ttpharm]

Hi yall,

After 2 days of running through the Destroyer I found some things I'm confused on, particularly with the Chemistries. I'm not posting the exact question but questions regarding the concepts that I discovered I didn't understand. I may have even gotten the question right but if they added other answer choices in there I wouldn't know what to do. You'll see what I mean.

Before I get started, what the hell do yall do with the Roadmaps? Is there any order to them? It just seems like random reactions coming from one starting material. How does that help yall learn the reactions?

1) What special properties does a carbon (or that carbon's hydrogens) that's alpha to two carbonyl carbons? I think with heat something degrades? Are those hydrogens acidic?

2) How do allylic radicals rank with the substituted radicals? Are they more stable than tertiary radicals?

3) p-nitroaniline vs o-nitroaniline, how come the para isomer crystallizes but not the ortho isomer? How do EDG and EWG affect cystallization?

4) Regarding chair conformations of cyclohexane, the infamous Br vs CH3. Which one gets the equatorial position? Destroyer says CH3, Chad says Br.

5) How do we know the physical states of certain compounds? ie. Cl2, K, W, Pb, Hg, Br2, Sb. Which ones would be liquids at room temp, etc?

6) Regarding the acidity of H's, can someone explain the trend between a H attached to an sp C, phenolic H, carboxylic H, and an aldehyde H? I know it has something to do with stability of the conjugate base but I can't seem to figure out which one would be more stable out of those.

7) With 3-methyl-2-butanone, there's 2 methy type carbons attached to carbon 3 (one's part of the skeleton), how come under CNMR, it shows up as a different peak? Shouldnt they be equivalent? They're both bonded to an alpha carbon.

8) When a ketone tautomerizes into the enol form (in acid), how come that alpha carbon acts like a nucleophile?

9) I thought molecules were polar if they had dipole-dipole interactions or hydrogen bonding, but I think it has something to do with the lone pairs on the central atom? Can someone explain that? (Gen Chem question)

10) Biology question: why does the turn over of nutrients occur in ponds/lakes from summer to spring/autumn?

11) Bio question: Endospores should inhibit proliferation too right? I always thought of an endospore as a bacteria hibernating bc conditions are bad. They typically stop proliferating and start saving up energy, or so I thought. Destroyer says that "endospore inhibits proliferation" is false.

Sorry for all the questions, I figured this could help any of yall studying right now anyways to kinda test yourself on some concepts. Thanks again for all your help!

PS - put the number of the question you're answering next to the answer! Once it's answered, I'll bold it or change the color or something on the original post so people will know which ones to answer without having to scroll.

1) What special properties does a carbon (or that carbon's hydrogens) that's alpha to two carbonyl carbons? I think wFith heat something degrades? Are those hydrogens acidic?

Decarboxylation: Treatment of a malonic ester with acid and
heat results in hydrolysis to the malonic acid (β-di-acid).
An acid group that is β to a carbonyl will lose CO2 upon heating.

2) How do allylic radicals rank with the substituted radicals? Are they more stable than tertiary radicals?

Allylic radicals are more stable due to delocalization. Allylic > tertiary > secondary > primary

3) p-nitroaniline vs o-nitroaniline, how come the paraisomer crystallizes but not the ortho isomer? How do EDG and EWG affect cystallization? I'm not completely sure. But I'm sure that the structure of o-nitroaniline has something to do with it. It may form a irregular crystal structure compared to p-nitroaniline.

4) Regarding chair conformations of cyclohexane, the infamous Br vs CH3. Which one gets the equatorial position? Destroyer says CH3, Chad says Br.

CH3 gets the equatorial position. I believe Chad said CH3 Also

5) How do we know the physical states of certain compounds? ie. Cl2, K, W, Pb, Hg, Br2, Sb. Which ones would be liquids at room temp, etc?

http://www.periodic-table.org.uk/states-of-matter.htm

6) Regarding the acidity of H's, can someone explain the trend between a H attached to an sp C, phenolic H, carboxylic H, and an aldehyde H? I know it has something to do with stability of the conjugate base but I can't seem to figure out which one would be more stable out of those.

Use CARDIO to rank bases. The more stable one, would be the weaker base/stronger acid. Stronger acid because it wants to lose the H and weaker base because it doesn't want to pick up an H. So some things that stabilize it are size of the atom and electronegativity. The next thing you should look at is resonance and then dipole induction, and then orbital.

an example of dipole induction is greater stability to least is tertiary > secondary > primary. Just like carbocations and radicals. For orbital, greater stability to least is sp > sp2 > sp3

7) With 3-methyl-2-butanone, there's 2 methy type carbons attached to carbon 3 (one's part of the skeleton), how come under CNMR, it shows up as a different peak? Shouldnt they be equivalent? They're both bonded to an alpha carbon.

8) When a ketone tautomerizes into the enol form (in acid), how come that alpha carbon acts like a nucleophile? The alpha carbon is electron rich so it can act like a nucleophile. Just like for a claisen condensation reaction, the alpha carbon H is acidic and is removed and can act like a nucleophile. Same concept.

9) I thought molecules were polar if they had dipole-dipole interactions or hydrogen bonding, but I think it has something to do with the lone pairs on the central atom? Can someone explain that? (Gen Chem question)
Moleculars are polar if it has a DIPOLE. Then it can initiate in dipole-dipole interactions with itself. A diple is formed when an atom more electronegative is bound to a less electronegative atom.

10) Biology question: why does the turn over of nutrients occur in ponds/lakes from summer to spring/autumn?

11) Bio question: Endospores should inhibit proliferation too right? I always thought of an endospore as a bacteria hibernating bc conditions are bad. They typically stop proliferating and start saving up energy, or so I thought. Destroyer says that "endospore inhibits proliferation" is false. I thought that too, but I guess proliferation just slows down and doesnt completely stop

Sorry for all the questions, I figured this could help any of yall studying right now anyways to kinda test yourself on some concepts. Thanks again for all your help!

PS - put the number of the question you're answering next to the answer! Once it's answered, I'll bold it or change the color or something on the original post so people will know which ones to answer without having to scroll

 

[TXpredent]

wow, thanks for the responses guys! I need to add what yall said to my notes now. I'm still up in there air on the CH3 vs Br on which one gets equatorial. I have specifically in my notes that Chad says Br bc it's a larger than CH3 on its own and has more mass. But Destroyer says CH3 because it's got 4 atoms.

Also, how did yall use Destroyer's road maps to study? I don't really see any order to it and like how Chad groups his reactions better. A lot of yall said that the road maps were amazing but I find them really hard to just plain memorize. Any thoughts?