Nomenclature, organic reactions...

[Ice-cream]

hey guys, can u help me with these few questions?

 

1. In the molecule below, which carbon atom is in the highest oxidation state?

 

BrCH2CH(OH)CH(OH)C(=O)CH2C(=O)OCH3

 

(I have NO idea of what to do!!! Can any1 help me?)

 

2. In the reduction of carbonyl compounds with LiALH4, the effective reducing species is: (a) Li+ (b) Al(3+) © AlH4(-) (d) AlH3 (e) H-

 

(i think the answer is c...any1 agree?)

 

3. What is the IUPAC name for the following compound?

CH3CH2CH2CH(Cl)C(=O)Cl

(a) 1-chloropentanoyl chloride

(b) 1-chloro-1-butanoyl chloride

© 2-chloropentanoyl chloride

(d) 1,2-dichloropentanal

 

(i think the answer is c...wat do u guys think?)

[Dak]

1/hmm... i dunno. id assume its the one thats is having its eletrons pulled away from it the hardest, but im not sure.

 

2/i always remember it as OILRIG: Oxidation Is Loss, Reduction Is Gain (of eletrons). so to be redused, something must gain eletrons. so to reduse a compound, the redusing species must have eletrons to give, so id agree with you that c) is the answre

 

3/all the functional groups are on the right, so well number from that side. lesse, 5 carbons (pent-)two chlorine atoms (dichloropent-) on the 1st and 2nd carbon, (1,2-dichloropent-) and a carbonyl group right up the end making it an aldahyde so id have called it 1,2-dichloropental, but my memories a bit fuzzy so i suppose it could be ~pentanal. if you google 1,2-dichloropentanal you might find its molecular formula.

[BenSon]

2)

In the reduction of carbonyl compounds with LiALH4, the effective reducing species is: (a) Li+ (b) Al(3+) © AlH4(-) (d) AlH3 (e) H-

2/i always remember it as OILRIG: Oxidation Is Loss, Reduction Is Gain (of eletrons). so to be redused, something must gain eletrons. so to reduse a compound, the redusing species must have eletrons to give, so id agree with you that c) is the answre

Firstly its not Oil Rig it Leo says Ger... Anyway the way i read this question it is looking for the strongest reductant, And a reductant causes oxidation. So the strongest reductant would be a cation because it is most likely to make someing lose electrons (oxidise). That being said i think the best choice would be Li+ or Al3+. I'd like to just put this out there though i usually tie myself up in knots doing these questions so i wouldn't be surprised if your right.

 

3) Yeah the answer is D

 

~Scott

[Dak]

i assumed that 'reducing species' was something that reduced something else, not something that reduced itself whilst doing something, but id like to add the same disclamer that you did. ie i get all confused with this.

 

also, it doesnt help that biochemists (ie chemists who study organic chemicals) and biochemists (ie biologists who know about chemistry) oftern use completely different words.

 

bloody nomclamenturial inconsistencys .

[Dak]

although having said that, if a reducing species is something that reduses something else, and if LiAlH4 contains H^- ion regions, then id assume that the H^- ions were your redusing species, as theyed be quite inclined to yield their extra eletron. maybe. oh im confused now, stuff it grumble grumble grumble stupid chemistry

[BenSon]

although having said that, if a reducing species is something that reduses something else, and if LiAlH4 contains H- ion regions, then id assume that the H- ions were your redusing species, as theyed be quite inclined to yield their extra eletron. maybe. oh im confused now, stuff it

No the H- would be a very poor reductant because it is meant to cause something to oxidise not reduce. In order for H- to be a reducant it would become H2- ! And that just not right.

 

Let me state the i took reducing agent to mean reducant (i'm not familiar with the term reducing agent) So if reducing agent means oxidant then reverse everything i have said....

 

~Scott

[Dak]

i did say that i was confused...

 

yes, of course if redusing species is something that reduces then H- would infact be a bad redusing species, what with it, in fact, being an oxidising speicies.

 

cheers for catching that one, benson.

[BenSon]

No worries, lets just hope i'm right!

 

~Scott

[Dak]

actually, i take that back. stop confusing me, hippy.

 

ok, i looked it up . a reducing species is one which provides eletrons for another chemical, ie a reducing species oxidises itself to reduce something else

 

oxidation is the loss of eletrons

 

reduction is the gain of eletrons

 

so, something that will lose eletrons is a reducing agent.

 

so AlH₄^- and H^- are both possible reducing agents as they have exess eletrons to lose. as to which one actually does the redusing, it depends. if the lithium dissociates from the rest of the compound, leaving Li⁺ and AlH₄^- ions, then id say AlH₄^- is the redusing species. if, however, the compound stays together and the hydrogen draws eletrons toward it/the lithium and aluminium push eletrons away from it, then the resulting H^- regions of the compound would be the reducing agents.

 

as to which one is the case.... i dunno. id also wait until someone else has confirmed/refuted this post before you believe it.

[Ice-cream]

so if AlH4 (-) and H- are both possible reducing agents...then how do u know which 1 it is in this question?

[Dak]

to be honest my brain has crashed. id like to remind you of my sujjestion to wait until my post has been commented on by another chemist before trusting it.

 

by-the-by, what level is this? if im having this much trouble with sub-A-level-difficulty chemistry, im going to sulk.

[BenSon]

Arghh your confused! my brain is about to melt. I told you i tie myself up in knots with this stuff I go around in circles think oxident-reductant-reducing agent-oxidised-reduced-oxidisingruducingchlorormatrixpentanol......I think your right i had it backwards I thought a reductant oxidised the other species (cuz i'm lost) but it actually oxidises itself thein lies my problem...

 

~Scott

[BenSon]

so if AlH4 (-) and H- are both possible reducing agents...then how do u know which 1 it is in this question?

LiAlH4 = Li+ AlH4-

I think this is the most likely breakdown of that so the answer would be AlH4- But I suck at chem which you can probly tell from this discussion but i have to get something right eventually.

 

~Scott

 

Edit: I just went back to the first post this guy had the right answer first up, sorry i caused so much confusion, I think I damaged his brain enough for one day

[Ice-cream]

well in australia, this is first year chemistry at university...so i dunno what that corresponds to in UK...

[Ice-cream]

well does any1 know about question 1? coz thats the 1 that I have absolutely no idea!

[Dak]

BrCH₂CH(OH)CH(OH)C(=O)CH₂C(=O)OCH₃

 

i think its the blue one above, cos it has 3 bonds to oxygens, and so id assume it is having its eletrons pulled away from it quite alot, which would (i assume) put it in a high state of oxidation, but im not entirely sure.

 

do you know if bromium is particualy oxidative?

[Guest METH MAN]

Ok guys the first question...

1.)for it 2 be in a state of oxidation, it must want to lose e-'s(LEO).

so i would say for sure that the double bonded oxygen is at the highest oxidation state as it has 2 unpaired e-'s, which no other molecule has, therefore these electrons r easily ripped off, thus Loss of Electrons = Oxidation.

 

Q2.) lets see (a) Li+ (b) Al(3+) © AlH4(-) (d) AlH3 (e) H- . <--- IF THESE R UR OPTIONS then... First know ur concepts. A reducing agent is a substance that wants to OXIDISE(leo) in order to give electron/s to another substance for it to reduce. Li+ occurs naturally, therefore it would want to gain a e- as with Al there is 2 out of the way. AlH4- = Al5- + H4+, there fore it wants to lose an e- to become stable(wants to b Al4- <-- loses e-, to stably join with H4+). H- is a rare occurance and occurs naturally as H+(H2O??????). So H- is going to gain a e-. therefore the only possible answer is AlH4-.

 

Q3.) for starters it is definately not an -al so © is out of the question. Y? u ask... well the structure is -CHO but our structure is -CCl

|| ||

O O

 

...... so if u look at ur notes or w\e u have... u will notice its a Acyl Halide.... or more known as the Prefix -Chlorocarbonyl(sound Familiar??). the longest CH chain is made of 4(but) but the longest Carbon chain is 5(pent). So we know(or should) that our suffix is -oyl chloride. And as all u chem buffs should no u always start numbering from the double bond. the chlorine on the end is the ending of our molecule as in the Chloride part so we dnt count it as it is not an add on. So the other chlorine is on the second carbon, thus we have our compound.......... 2-Chloropentanoyl chloride ................ which is (d)

 

 

 

I might be a bit l8 to help u guys but i only found this site today sorry