Name Compounds: Homework Solutions

[Physics345]

Homework Statement

Name the following compounds.

Sorry for the rough structures, I couldn't get them to go on paint better than this for some reason :S

Homework Equations

none

The Attempt at a Solution

a) The molecular compound is 2, 3, 5-trimethylhexane

b) The molecular compound is 6 -ethyl- 2, 3, 5, 7-tetramethyloctane

c) The molecular compound is 2, 2-dimethylpentane

d) 1- ethyl-3-methylcyclopenten

e) 4, 4 – dimethyl-2-pentyne

f) 2-methyl-1,1,2-tribromoethene

g)1,3-pentanol

h) 2-methyl-3-pentanon-5-fluoro

i) 4,4-methylhexanoic acid

j) 3- Cholorobutanamide

k) Propanylhexonate

 

[Physics345]

Did I do these correctly?

 

[Borek]

You do understand we are not a homework checking service?

Some are wrong - for example f is propene, g is not based on pentane.

 

[Physics345]

You do understand we are not a homework checking service?

Some are wrong - for example f is propene, g is not based on pentane.

I never said you were, I just wanted to see if I was wrong so I could ask why and get some tips to help me learn.

Why exactly is f) propene? There is only two carbons on the main chain wouldn't that make it ethene based?
For g) I guess i miscounted the carbons on the main chain. Making the correct answer 1,3-butanol.

 

[Borek]

There is only two carbons on the main chain

Rethink what the main chain is.

 

[Physics345]

Rethink what the main chain is.

Isn't it the chain with the most carbon atoms?

 

[Borek]

Exactly. Now look at the molecule again.

 

[Physics345]

Exactly. Now look at the molecule again.

Wouldn't the methane be a side chain? I thought when we see branches they are the side chains.

 

[Borek]

chain with the most carbon atoms

How can any C in C-C-C be a side chain?

 

[Physics345]

How can any C in C-C-C be a side chain?

Hmmm, I'm seeing it like this, I don't see how the CH3 is part of the main chain when it's branching out.

 

[Borek]

Nope, that's not how it works. How is the C=C the longest chain, if the C=C-C is longer?

 

[pinball1970]

I never said you were, I just wanted to see if I was wrong so I could ask why and get some tips to help me learn.

Organic nomenclature follows very specific rules If you do this on the fly every time without following regimented steps you will get caught out

What level are you at? Is this pre university?

There are resources on the net for this and your OC textbook should have a section on IUPAC names

https://en.wikipedia.org/wiki/IUPAC_nomenclature_of_organic_chemistry

 

[Physics345]

Nope, that's not how it works. How is the C=C the longest chain, if the C=C-C is longer?

Okay after redrawing it like this, I figured out how this works.

Am I on the right track here?
Also the actual name would be 1,1,2-tribromopropene correct?

 

[Physics345]

Organic nomenclature follows very specific rules If you do this on the fly every time without following regimented steps you will get caught out

What level are you at? Is this pre university?

There are resources on the net for this and your OC textbook should have a section on IUPAC names

https://en.wikipedia.org/wiki/IUPAC_nomenclature_of_organic_chemistry

This is pre university chem, I am re learning everything from scratch after being out of school for 8 years before I start electrical engineering in September. It's been a long learning curve, but I have been getting by with the help of some wonderful people on this site.

 

[Borek]

View attachment 222263
Am I on the right track here?

Yes. Note the longest chain doesn't have to be straight.

Also the actual name would be 1,1,2-tribromopropene correct?

Close, but in general it is incomplete. You correctly named the main chain and you indicated positions of Br atoms, but to be absolutely correct you should also mention where is the double bond, as the name is a bit ambiguous (1,1,2-tribromoprop-1-ene and 1,1,2-tribromoprop-2-ene being two possibilities, in the latter case name does not follow IUPAC rules exactly - double bond should be at atom 1 - but is perfectly understandable).

 

[TeethWhitener]

Am I on the right track here?

sp2 carbons are tricoordinate (only have three things attached to them). Your picture in post 13 has double bonded carbons with four substituents, which is incorrect. The parent carbon chain is simply the longest number of C's in a row. Regardless of if you have C-C-C-C... or C=C-C=C... or C≡C-C=C... or whatever.

 

[Borek]

Your picture in post 13 has double bonded carbons with four substituents, which is incorrect.

Good point, missed that :(

 

[Physics345]

At this point it might be best for me to redo the lessons. I'll be back with proper answers in a little bit.

 

[pinball1970]

At this point it might be best for me to redo the lessons. I'll be back with proper answers in a little bit.

Ok, getting the answers right in this instance should not be your goal (it helps!) Get a load of examples and spend 15 minutes with your tutor show him your technique. Its easy to get stuck as there so many permutations and combinations but if you have a stab at as many examples as possible there should not be too many surprises in your term tests.

 

[Borek]

Ok, getting the answers right in this instance should not be your goal (it helps!) Get a load of examples and spend 15 minutes with your tutor show him your technique. Its easy to get stuck as there so many permutations and combinations but if you have a stab at as many examples as possible there should not be too many surprises in your term tests.

Great that you have read earlier posts in the thread before commenting.

 

[Physics345]

Ok, getting the answers right in this instance should not be your goal (it helps!) Get a load of examples and spend 15 minutes with your tutor show him your technique. Its easy to get stuck as there so many permutations and combinations but if you have a stab at as many examples as possible there should not be too many surprises in your term tests.

Okay I redid all the lessons. I now have the right answers, at least I think. Let me know if I did any wrong, so I can go and work harder on that part of the lessons.

a) 2,3,5-trimethylhexane
b) 3-ethyl-2,4,6,7-tetramethyloctane
c)2,2-dimethylpentane
d) 1-ethyl-3-methyl-1-cyclopentene
e) 4,4-dimethyl-2-pentyne
f) 1,1,2-tribromo-1-propene
g)1,2-butandiol
h) 1-fluoro-4-methyl-3-pentanone
i) 4,4-dimethylhexanoic
j) 3-chlorobutanamide
k) propylheptanoate

 

[pinball1970]

Great that you have read earlier posts in the thread before commenting.

Thanks - new to the site in terms of posting although I have been a member for a few years

 

[Borek]

Note: there is a free program called ChemSketch that - between other things - generates IUPAC names for molecules drawn. This way you can always quickly check if your name is a correct one.

 

[Physics345]

Are you referring to this http://www.acdlabs.com/products/draw_nom/draw/chemsketch/ ?

 

[Borek]

Are you referring to this http://www.acdlabs.com/products/draw_nom/draw/chemsketch/ ?

Yes. Sadly, unless I am missing something looks like they have changed the license, I see no free version (other than the trial).

 

[Physics345]

Well I downloaded the free trial, let's see how it is.

 

[Borek]

Draw a molecule, then Tools/Generate/Name for structure.

 

[Borek]

Seems like the freeware version still exists: http://www.acdlabs.com/resources/freeware/chemsketch/

 

[Physics345]

It seems nice and all, but Id rather master naming my self rather than use that. I kind of feel like I'm cheating using something like that.
At this point I'm just going to keep practicing until I master it.
Also I really appreciate all the help I got from you all, I'll be sure to keep practicing. I'm going to move on to the next section as I practice and work on some physics (I love physics!), calculus and physics I found to be straightforward chem feels like I'm learning a new language its been a bit more challenging for me to learn. Either way you should hear back from me soon I always manage to get stuck at some point. With the help of the awesome people on here I manage to climb over every bump and I plan to continue doing so. See you soon :)

 

[Borek]

I am not suggesting you use it to name things - just to check if your names are correct. Much faster and much more effective than waiting for someone here to chime in (and take into account fact that when you post long list of molecules we are at best skimming it, so while it may happen we spot something obvious we can as well miss something, ChemSketch won't).