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Topic: Help with practice homework problems  (Read 5332 times)

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Taylor

  • Guest
Help with practice homework problems
« on: April 23, 2005, 11:36:18 AM »
Hey,
I could really use some help on this homework that i was given to practice for an upcoming test I have on monday, I was given five different problems that have mass specs,Ir Spectormetry,and H Nmr, and C13 NMR graphs and the object is to determine the actual structure of the molecule based on all of the clues. I would really appreciate if someone could help me figure out the five structures and an explanation for each. I have attached the five problems.
MY Work

problem # 5  formula is c4H6O: from the IR spectroscopy there is an OH and also there is a Sodar of 2, which I think is a Triple bond from the chemical shift of one of the carbons on the C13 HNMR, there are four types of carbons and four types of hydrogens in the ratio left to right (2:1:2:1)-however I have a tough time determing the actual structure! I want to think is is close to OH-Ch2-Ch2-C(triplebond)CH-but it isnt exactly right.

problem # 12 formula I think is C9/H10/O2 with a sodar of five, meaning that I assume there is a benzene ring involved because the ring accounts for a sodar of four, I also think there is a C=O because of a peak at 1700 on the IR spectrocopy: 7 different types of Carbons and 4 differnt types of aromatic carbons, also there is also most likely and ethyl substitute because of the quartet downfield from the triplet, the protons are in a ratio left to right (1:2:2:2:3), meaning five different types of protons. I think it has to be a benzene ring with and ethyl group coming off on one side and possible mabey and ester off the other side? sorry I just cant seem to put the final structures together.

problem # 9 I am really stuggling to even get the formula, I seem to get C10H23N but that is giving me a sodar of negative 1 which doesnt make sense. there seems to be only four different types of carbons and most of them sp3 except for one that is shifted downfield most likely becaue it is attached to the N, I also am not to sure what is meant by overlapping multiplets, from the IR it may appear that there is a C-N and then there are three different types of Hydrogens

I am still working on #16 and #24 but I will update this when I get back from lunch to show my work on those two problems> I am greatly appreciative for your time and help
Thanks alot!!!!!
 :) Taylor
« Last Edit: April 23, 2005, 12:12:35 PM by Taylor »

Garneck

  • Guest
Re:Help with practice homework problems
« Reply #1 on: April 23, 2005, 02:07:23 PM »
Try here: http://www.aist.go.jp/RIODB/SDBS/cgi-bin/direct_frame_top.cgi?lang=eng

Compund 5: 3-butyn-1-ol
SDBS No.: 56

Compund 12: p-ethylbenzoic acid
SDBS No.: 13185

Compound 9: dipentylamine
SDBS No.: 21782

Taylor

  • Guest
Re:Help with practice homework problems
« Reply #2 on: April 23, 2005, 03:48:23 PM »
Alright, Great thanks a lot, This helps me to put the structures together, Im decent at the clues just have to figure out how to put all the clues together, practice,practice,and more practice I guess.
Thanks ;D
Taylor

Garneck

  • Guest
Re:Help with practice homework problems
« Reply #3 on: April 23, 2005, 04:05:22 PM »
Yes, practice in this case is very important.

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