Quiz 3 Preparation

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Kimberly Govea 2L
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Quiz 3 Preparation

Postby Kimberly Govea 2L » Sat Feb 27, 2016 8:38 pm

For the question #2 on page 43, it states to name the compound CH3CH(CH3)CH(CH2CH3)C(CH3)3.

I have named the compound 3-ethyl-2,2,4-trimethyl pentane but the answer says its 2,2,4-trimethyl-3-ethyl pentane. Why?

Chem_Mod
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Re: Quiz 3 Preparation

Postby Chem_Mod » Sat Feb 27, 2016 9:18 pm

Your answer is correct.

204408136
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Re: Quiz 3 Preparation

Postby 204408136 » Sun Feb 28, 2016 5:15 pm

Both answers will be correct then?

Stevie Wisz
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Re: Quiz 3 Preparation

Postby Stevie Wisz » Sun Feb 28, 2016 5:20 pm

So, on the quiz would both answers be correct?

chrispolo15
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Re: Quiz 3 Preparation

Postby chrispolo15 » Sun Feb 28, 2016 5:35 pm

for question number 5 on the first quiz, why is Iodine chosen as the starting point rather than Bromine? does it matter?

Jessica Kwan 3B
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Re: Quiz 3 Preparation

Postby Jessica Kwan 3B » Sun Feb 28, 2016 6:36 pm

@chrispolo15 It does matter. Priority is based on atomic number of the atom bound to the carbon and I has a higher number than Br.

Evelin Escobedo
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Re: Quiz 3 Preparation

Postby Evelin Escobedo » Sun Feb 28, 2016 7:48 pm

Would someone be able to walk through how to get to either answer ?? I am still getting confused on these types of questions.

jennymai96
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Re: Quiz 3 Preparation

Postby jennymai96 » Sun Feb 28, 2016 9:51 pm

Can anyone explain the difference between benzene and phenyl ring? How do we distinguish between the two?

504549031
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Re: Quiz 3 Preparation

Postby 504549031 » Sun Feb 28, 2016 10:29 pm

Benzene has 6 hydrogens to go with the 6 carbons that give it its structure. A phenyl ring has 6 carbon atoms, but only 5 hydrogen atoms.

Anna Johnosn 1C
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Re: Quiz 3 Preparation

Postby Anna Johnosn 1C » Sun Feb 28, 2016 10:30 pm

In the first Quiz 3 Preparation on page 44 number 6 I named the compound using "neo", while the answer instead uses "tert". Would both answers be correct or is neo not used? If not, why is that?

Johnchou1A
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Re: Quiz 3 Preparation

Postby Johnchou1A » Sun Feb 28, 2016 10:33 pm

chrispolo15 wrote:for question number 5 on the first quiz, why is Iodine chosen as the starting point rather than Bromine? does it matter?



I had the exact same question. I always thought that since bromine comes first alphabetically, it must be assigned the lower number. Therefore you Bromine would be numbered 1? Is this not the case?

JasmineChavez 1E
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Re: Quiz 3 Preparation

Postby JasmineChavez 1E » Sun Feb 28, 2016 11:15 pm

Could someone draw out this compound and explain the different parts of the name in correspondence with the compound because I tried and I looked it up but its confusing me.

Shelby Yee 1J
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Re: Quiz 3 Preparation

Postby Shelby Yee 1J » Mon Feb 29, 2016 12:34 am

@Johnchou1A the Iodine gets ultimate priority since it has a higher atomic number, therefore, iodine should be 1 and bromine should be 3

Johnchou1A
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Re: Quiz 3 Preparation

Postby Johnchou1A » Mon Feb 29, 2016 12:36 am

Shelby Yee 1J wrote:@Johnchou1A the Iodine gets ultimate priority since it has a higher atomic number, therefore, iodine should be 1 and bromine should be 3


Do we look at the atomic number only when we deal with halogens as substituents then?

studdmuffin
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Re: Quiz 3 Preparation

Postby studdmuffin » Mon Feb 29, 2016 10:54 am

I thought priority was only considered when evaluating geometric isomers... in halogenated compounds the halogens are treated as substituents and are organized alphabetically. Double and triple bonds are still given priority.

Jocelyn
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Re: Quiz 3 Preparation

Postby Jocelyn » Mon Feb 29, 2016 12:51 pm

So, just to clarify both answers wold be correct in this case right?

Reine Nakamura 1C
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Re: Quiz 3 Preparation

Postby Reine Nakamura 1C » Mon Feb 29, 2016 4:59 pm

Kimberly Govea 2L wrote:For the question #2 on page 43, it states to name the compound CH3CH(CH3)CH(CH2CH3)C(CH3)3.

I have named the compound 3-ethyl-2,2,4-trimethyl pentane but the answer says its 2,2,4-trimethyl-3-ethyl pentane. Why?


For this question, I would say that your answer is correct because when putting the substituents in alphabetical order, you would disregard the tri on methyl. Therefore if you compare methyl to ethyl, 'e' comes before 'm' making the correct order ethyl then trimethyl.

To be safe, I would recommend writing the answer as you did (using alphabetical order for the substituents).
Last edited by Reine Nakamura 1C on Mon Feb 29, 2016 6:51 pm, edited 2 times in total.

Reine Nakamura 1C
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Re: Quiz 3 Preparation

Postby Reine Nakamura 1C » Mon Feb 29, 2016 6:39 pm

studdmuffin wrote:I thought priority was only considered when evaluating geometric isomers... in halogenated compounds the halogens are treated as substituents and are organized alphabetically. Double and triple bonds are still given priority.


Chem_Mod wrote:I believe the correct answer should be 1-bromo-3-iodo because all halogens have the same priority (also the same as alkyl groups so bromo<butyl<chloro<ethyl<iodo<methyl<propyl like this). And the first alphabetical substituent gets the lower number.


According to this response from one of the TA's/UA's, I believe the answer key was incorrect and it should be 1-bromo-3-iodocyclohexane.

Cecilia Tsai 3C
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Re: Quiz 3 Preparation

Postby Cecilia Tsai 3C » Mon Feb 29, 2016 7:02 pm

Is 3-Bromo-1Iodocyclohexane wrong for number five then?

Amanda Nguyen 2E
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Re: Quiz 3 Preparation

Postby Amanda Nguyen 2E » Mon Feb 29, 2016 8:52 pm

Is number 2's (on the first quiz prep) IUPAC name 3-ethyl-2,2,4-trimethyl pentane and its common name 3-ethyl-2-methylneoheptane?

Curtis Ngo_4E
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Re: Quiz 3 Preparation

Postby Curtis Ngo_4E » Mon Feb 29, 2016 8:53 pm

Will we be asked about common names on the quiz? Or only IUPAC naming?

Cristian Yanes 1L
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Re: Quiz 3 Preparation

Postby Cristian Yanes 1L » Mon Feb 29, 2016 10:07 pm

Curtis Ngo_4E wrote:Will we be asked about common names on the quiz? Or only IUPAC naming?


Hi my good pal Curtis,

I believe I read on another post from a TA that we will be asked about both common names and IUPAC naming.

tinaZ
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Re: Quiz 3 Preparation

Postby tinaZ » Mon Feb 29, 2016 10:39 pm

will there be the natural log stuff that didn't get covered on the last quiz?

Daniela Contreras 3E
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Re: Quiz 3 Preparation

Postby Daniela Contreras 3E » Tue Mar 01, 2016 7:51 pm

In the course reader on page 87 the arrow from the C,C double bond would indicate that 2 electrons are moving correct ? Is that true however?

Chem_Mod
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Re: Quiz 3 Preparation

Postby Chem_Mod » Tue Mar 01, 2016 9:31 pm

Please see my many quiz 3 answers at viewtopic.php?f=2&t=12738

Note: Quiz 3 Preparation Answers had two errors. They should be:

Q2. 3-ethyl-2,2,4-trimethyl-pentane

Q5. 1-bromo-3-iodocyclohexane

jyc185
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Re: Quiz 3 Preparation

Postby jyc185 » Tue Mar 01, 2016 9:59 pm

Hi is there supposed to be a - between the methyl and pentane? or could we just write it s 2,2,4-trimethyl-3-ethylpentane?

Yuanming Mao 3J
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Re: Quiz 3 Preparation

Postby Yuanming Mao 3J » Wed Mar 02, 2016 1:03 am

In the preparation 2, the answer of q5 is a structural formula, but the question asks for the molecular formula. Should the answer be C4H9Br?

Chem_Mod
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Re: Quiz 3 Preparation

Postby Chem_Mod » Wed Mar 02, 2016 9:21 am

jyc185 wrote:Hi is there supposed to be a - between the methyl and pentane? or could we just write it s 2,2,4-trimethyl-3-ethylpentane?


The answer is 3-ethyl-2,2,4-trimethyl-pentane or 3-ethyl-2,2,4-trimethylpentane.
I often insert - to make it easier for students to read.
3-ethyl-2,2,4-trimethylpentane would be the best way to write it.

Chem_Mod
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Re: Quiz 3 Preparation

Postby Chem_Mod » Wed Mar 02, 2016 9:25 am

Yuanming Mao 3J wrote:In the preparation 2, the answer of q5 is a structural formula, but the question asks for the molecular formula. Should the answer be C4H9Br?


Correct. The product is CH3CH2CHBrCH3 with a molecular formula C4H9Br.

Zane Mills 1E
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Re: Quiz 3 Preparation

Postby Zane Mills 1E » Wed Mar 02, 2016 11:01 am

Like on question #5, I understand that the slow step in an addition reaction is the limiting step, but will the slow step always be the 1st step as well?

Chem_Mod
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Re: Quiz 3 Preparation

Postby Chem_Mod » Wed Mar 02, 2016 12:50 pm

Mane Zills wrote:Like on question #5, I understand that the slow step in an addition reaction is the limiting step, but will the slow step always be the 1st step as well?


For all reactions, no.

Ilya Alter 3J
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Re: Quiz 3 Preparation

Postby Ilya Alter 3J » Wed Mar 02, 2016 7:22 pm

Just to clarify, do the parenthesis in the equations indicate a substituent?

eg:
CH3CH(CH3)....etc.

Mayvera Doaran 2H
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Re: Quiz 3 Preparation

Postby Mayvera Doaran 2H » Wed Mar 02, 2016 8:07 pm

303747052 wrote:Just to clarify, do the parenthesis in the equations indicate a substituent?

eg:
CH3CH(CH3)....etc.


Yes, parenthesis indicate substituents!

Ilya Alter 3J
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Re: Quiz 3 Preparation

Postby Ilya Alter 3J » Thu Mar 03, 2016 1:30 am

Mayvera Doaran 2H wrote:
303747052 wrote:Just to clarify, do the parenthesis in the equations indicate a substituent?

eg:
CH3CH(CH3)....etc.


Yes, parenthesis indicate substituents!


Great, thank you for the reply.

Francesca Genera 3F
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Re: Quiz 3 Preparation

Postby Francesca Genera 3F » Fri Mar 04, 2016 10:00 am

thanks!


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