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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?
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?
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.
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.
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.
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.
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.
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.
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