Quiz 3 Preparation

[Kimberly Govea 2L]

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]

Your answer is correct.

[204408136]

Both answers will be correct then?

[Stevie Wisz]

So, on the quiz would both answers be correct?

[chrispolo15]

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]

@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]

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

[jennymai96]

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

[504549031]

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]

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]

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]

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]

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

[Johnchou1A]

@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]

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]

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

[Reine Nakamura 1C]

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).

[Reine Nakamura 1C]

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.

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]

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

[Amanda Nguyen 2E]

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]

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

[Cristian Yanes 1L]

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]

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

[Daniela Contreras 3E]

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]

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]

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]

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]

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]

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]

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]

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]

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

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

[Mayvera Doaran 2H]

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

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

Yes, parenthesis indicate substituents!

[Ilya Alter 3J]

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]

thanks!