Naming [ENDORSED]

[Tara_Hekmati_3B]

How do you determine where to put the dashes within the name of the organic compound? I think there are several instances where you would use one, but I just wanted some clarification.

[Nerissa_Low_2F]

I think dashes are typically used to separate numbers from words but I'm not completely sure.

[Anjum Farook 2O]

I believe you use dashes not just to separate numbers but also prefixes/suffixes. e.g. 3-ethyl-5-methyl-octane

[emilie liu 3G]

Yes, you use the dashes to separate words from numbers, but the example 3-ethyl-5-methyl-octane would not need a dash between methyl and octane so it would essentially be written 3-ethyl-5-methyloctane

[nikita bhat 2D]

What do the numbers represent?

[Arshia_Sabir_3E]

I think they represent which carbon is the group attached to. For instance, In 3-ethyl-2-methylhexane. Hexan shows a 6 carbon chain and since there are two
different alkyl groups attached, we put an ethyl group on the number 3 carbon atom and a methyl group on the number 2 carbon atom.

[Chem_Mod]

Yes, you use the dashes to separate words from numbers, but the example 3-ethyl-5-methyl-octane would not need a dash between methyl and octane so it would essentially be written 3-ethyl-5-methyloctane

Correct.

In class I often add a dash to separate the substituent from the main chain word to make it easier for students to identify the different parts of the name. For example: 3-ethyl-5-methyl-octane

However the way it would be printed in a book or science journal is: 3-ethyl-5-methyloctane

We will accept both.

[Bronson_Barretto_2C]

What do the numbers represent?

The numbers are used to represent which Carbon in the parent chain the substituent is attached to. For example, in 4-methyl-octane, the methyl substituent is attached to the 4th carbon in the octane parent chain. Counting carbons from the left, you will get that the substituent is on the 4th carbon; counting from the right, you will get that the substituent is on the 5th carbon. In all cases, you will choose the lowest number, so 4-methyl is written instead of 5-methyl.

[604735966]

What does it mean when it has "#,#" before the name? Which number means which thing?

[feodora_r_3d]

With #,# do you mean something like 2,3 dimethyl octane? If yes, then I think the numbers are to indicate which carbon the methyl is placed on. So if its 2,3 it means that on the second and third carbon, there is a methyl branch

[Caleb Lim 2M]

How do we know in what order we should put the numbers? (because we can start counting from either side of the molecule)

[Diego Cortez 2J]

How do we know in what order we should put the numbers? (because we can start counting from either side of the molecule)

You number the substituents based off the lowest number/location on the parent chain.

[AnnaTong1E]

It should be the smallest number - from either end of the chain.

[Michelle Kam 1F]

we use the dashes to separate numbers from words.
For example, 3-methyl-2-ethylpropane
Note that we do not use the dashes when separating two numbers; instead, we use a comma.
Like this, 2,3-dimethylbutane

Also, the name of our last substituent and the name of our longest carbon chain (the parent chain) will be connected (no space in between)

[NinaSheridan]

There was also a thing Lavelle mentioned about not using a dash sometimes for the second to last term? It's in our course reader but was different on the powerpoint or something like that.

[Teresa Chan 2G]

There was also a thing Lavelle mentioned about not using a dash sometimes for the second to last term? It's in our course reader but was different on the powerpoint or something like that.

Yeah the last carbon group doesn't need a dash, it just combines with the parent group, for example 3-ethyl-2,3-dimethylpentane or something.

[ariana_cruz_1C]

I'm not sure if this is an obvious answer but on page 93 of the course reader what do the numbers (1,2,2) in 1-Bromobutane, 2-Chlorobutane, &
2-Iodobutane mean?

[Jeffrey_Huang_2K]

Those numbers refer to the carbon to which the halogen is attached, numbering follows the same rules, so the lowest numbering scheme is chosen.

[ChristineCastanon_1B]

What do the numbers represent?

The numbers represent which carbon the substituents are added to. You number the carbons on the longest chain and it could start on the right or left side, but in the end, you number it so that the substituent is bonded to the lowest number carbon.

[KarinaOropeza_2L]

Will the order always be in alphabetical order when naming the structures ?

[Leo_Navejas_3B]

For substituents do we use common or systematic naming??

[104781135]

On page 93 of the course reader, we choose 4-ethyl-2,2-dimethyl-hexane as the correct name of the molecule instead of 3-ethyl-5,5-dimethyl-hexane. We are always supposed to choose the name with the lowest number, so why do we choose 4-ethyl instead of the 3-ethyl? Is it dependent on the dimethyl only?

[Ana_Andrade_1A]

On page 93 of the course reader, we choose 4-ethyl-2,2-dimethyl-hexane as the correct name of the molecule instead of 3-ethyl-5,5-dimethyl-hexane. We are always supposed to choose the name with the lowest number, so why do we choose 4-ethyl instead of the 3-ethyl? Is it dependent on the dimethyl only?

Just whichever has the lowest number overall, which in this case is dimethyl.

[Thomas_Elizabeth_3A]

Will the order always be in alphabetical order when naming the structures ?

Yes, the order is always in alphabetical order when naming the structures, based on the substiuents.

[Ana_Andrade_1A]

For substituents do we use common or systematic naming??

I believe that Professor Lavelle said that either is acceptable but they'd specify if they want the IUPAC name.

[AonyaMontoya2B]

Why is there a 2 in pentanone for CH3COCH2CH2CH3

[Ana_Andrade_1A]

Why is there a 2 in pentanone for CH3COCH2CH2CH3

It is a ketone which means there is a double bond attached to a carbon in the parent carbon chain which is bonded to two other carbons and since this is your functional group and you want to have the lowest possible number you start counting from whichever end gives you the lower number and in this case it is 2, and the longest carbon chain has 5 carbons which makes it 2-pentanone.

[bridgetfoy_1D]

On page 3 of the OChem textbook at the bottom, how do you get the "-diene" at the end of the molecule 2-Methyl-1,3-butadiene? Also, I'm confused on how to start the numbering for this example. Which Carbon is 1, and what order/direction do you go from there?

[Armani Dodson 1A]

Are the pentyl and amyl in the course reader the same thing? If so, which one should we use for common naming, or does it matter?

[Navarro_Bree_1D]

Pentyl is the IUPAC naming and amyl is the common naming

[LeontyneHenderson2E]

When we name an alkene or alkyne with a functional group, do we put the number for the double/triple bond inside the word or in front of the word? For example, is it 2-pentene or pent-2-ene.

[Mirian_Garcia_2G]

I believe that its not necessary in between names, but it is for in between numbers and names. Lavelle mentioned that the dashes in between names were meant to avoid confusion and promote better understanding of the different parts when teaching the material.

[Bryan Vega 2E]

Would a prefix, such as "di" in dimethyl, affect the order when naming alphabetically?

[Josephine_Tang_1N]

Will the order always be in alphabetical order when naming the structures ?

Sometimes it can vary if there's a "substituent in a substituent" type of situation (i.e. IUPAC naming for isopropyl branch would be 2-methylpropyl which would be included amongst other substituents if applicable). The propyl could be in front of another substituent name like nonyl even though it is not alphabetically first since it is part of the branch.

[Josephine_Tang_1N]

Would a prefix, such as "di" in dimethyl, affect the order when naming alphabetically?

no!

[Jaime_Chamberlain_3G]

When you add the numbers to the name, I know that the position is the first number, but what is the number after the name? Ex. 3-methyl-5,5-pentanehexane or whatever it would be. Thank you.

[Elias Ruben 1O]

In one of the course reader examples for cycloalkanes (around pg. 93 of the course reader), it shows 1-tert-butyl-4methylcyclohexane. Why is there a "tert" before the butyl? I don't understand why it isn't just called "butyl"

[Diondraya_Taylor_1C]

The "tert" is before "butyl" to show that the 4 carbon substituent comes from 1 carbon being connected to 3 other carbons rather than it just being a chain of 4 carbons associated with "butyl" by itself. Hope that helps!

[Joslyn_Santana_2B]

What counts when using the alphabetical reference when naming?

I thought Neo- and Iso- counted, while Tert- didn't? Or is it the opposite? Is there a reason for it?

Thanks in advance.

[Joslyn_Santana_2B]

For substituents do we use common or systematic naming??

I was told common and systematic naming are the same thing.

[rielapopp3O]

What do "Z" and "E" mean?

[Jerry Wang 1L]

You can think of Z as having the higher priority groups on the same side of the molecule (also known as "cis" and hence the mnemonic "Zee Zame Zide") and E as having the higher priority groups on the opposite sides of the molecule (also known as "trans"). When looking at the groups bonded to the same carbon, higher priority is determined by whichever group has the higher atomic number (for example: Br has priority over H because atomic number of Br is 35 and H is 1). Without using Z or E, there will be two possible structures that would have the same name, thus Z and E are necessary.

[Rodri_Karla_1J]

I have a question about page 94 in the course reader from yesterday's lecture. We went over pentyl and isopentyl, but I thought you use neo instead of iso for pentane and beyond. Shouldn't the name be neopentyl instead of isopentyl?

[jeree pucan]

If there are 2 substituents on the same Carbon do we use "di" or just 2?

[veeksha25]

If there are two methyls, for example, on Carbon number 2; then you would write it as 2-dimethyl. Similarly, if it was on Carbon #3, it would be 3-dimethyl.

[TiengTum2D]

I have a question about page 94 in the course reader from yesterday's lecture. We went over pentyl and isopentyl, but I thought you use neo instead of iso for pentane and beyond. Shouldn't the name be neopentyl instead of isopentyl?

Neo is used for substituents that have the formula C(CH3)3 while iso is used for those with CH(CH3)2. I hope it helps!

[Karishma_Patel3E]

You separate numbers form words with dashes (i.e. 3-ethyl)

[Tycho_Meimban_2B]

Dashes are used to separate not only numbers of the location of the substituents, bonds, etc., but also substituents. For example, for 2-methyl-pentane, we know that on the second carbon of the carbon chain of pentane, there is a methyl substituent located.

Hope this helps!

[Bryan Vega 2E]

If there is multiple functional groups which group gets the highest priority?

[Chem_Mod]

If there is multiple functional groups which group gets the highest priority?

As I discussed in class Chem 14B syllabus does not cover multiple functional groups. This is covered in Chem 14C/CL/D.

[PriscillaMariscal_3F]

When naming should we always include if a compound is cis/trans, or will a question specifically ask us for that information?

[Chem_Mod]

When naming should we always include if a compound is cis/trans, or will a question specifically ask us for that information?

If the molecule can exist in the cis or trans form, you must specify which one it is.

[Ethan_Wilson_1E]

It seems like there are a lot of structures in the Introduction to Organic Chemistry book that could be named using either -neo and -iso or sec, tert, etc. Is there a specific time and place for using one form versus the other, or are both acceptable forms of the name?

[EmilyLeibovitch2E]

I think generally iso and neo are for alkyl groups and sec and tert are used for carbon atoms which have functional groups

[Leo_Navejas_3B]

Also what about bis?

It seems like there are a lot of structures in the Introduction to Organic Chemistry book that could be named using either -neo and -iso or sec, tert, etc. Is there a specific time and place for using one form versus the other, or are both acceptable forms of the name?

[Ruiz Samantha 2C]

I'm still a little confused on the difference between IUPAC and common names. Can someone please explain.

[Andrea Medina 1A]

When theres both a double bond and a functional group group which gets priority?

[Andrea Medina 1A]

Still having trouble with knowing where to start counting the carbons when there is a double bond, any clarification

[Drake_Everlove_1K]

Does using common names (for substituents like isopropyl, for example) make a difference in the use of dashes?

[tpat14]

When you add the numbers to the name, I know that the position is the first number, but what is the number after the name? Ex. 3-methyl-5,5-pentanehexane or whatever it would be. Thank you.

The second number (-5) is not in regards to the methyl, it is talking about the pentanehexane.

[shreya_mantri_3I]

A question: Is the functional group given preference over a double or triple bond during naming? Or is the double or triple bond given preference over the functional group?

[Alex Uy 2D]

If i am trying to add -oxy onto the end of isopropyl, would it become or isopropylanoxy or just isopropyloxy?

[204781248]

When theres both a double bond and a functional group group which gets priority?

the functional group gets priority.

[204781248]

A question: Is the functional group given preference over a double or triple bond during naming? Or is the double or triple bond given preference over the functional group?

the functional group is given priority.

[Jaret Nishikawa]

Do you prefer us to write the number on the outside of the name, or embedded in the functional group (but-1-amine for example)?

[Mihika Sridhar 3H]

I know substituents must be written alphabetically but when there are halides with additional alkyl substituents, do they halides always come first (alphabetically) followed by all the alkyl groups (alphabetically)? For example would it be 3-iodo-4-ethyl... Or 4-ethyl-3-iodo... ?

[Andrea Medina 1A]

Not quite sure how 3-5,Dimethylbenzene-1ylium is the lowest number for self test4.2A????

[Jorge_Escobar_3L]

In Class we went over Cis and Trans molecules in a hexane when the substituents where on carbon 1 and 4. If say the substituents were on 1 and 3, would we still be determining cis and trans?

[Samantha Rubin-Pope - 1H]

Do you prefer us to write the number on the outside of the name, or embedded in the functional group (but-1-amine for example)?

I believe on the outside.

[MariaReina_Garcia_3E]

Still having trouble with knowing where to start counting the carbons when there is a double bond, any clarification

If there is only a double bond in the molecule then you start counting on the side which gives it the lowest number. If there is a functional group and a double bond, then you give the lowest number to the functional group because it has priority.

[Divya Kumar 3I]

I'm a little confused on what cases to use prefixes like iso and neo rather than the normal numbering

[Caleb Lim 2M]

In Q6A of the 2013 practice Final Exam, the answer is either 1,5,5,6-tetramethylcyclohex-1-ene or 1,5,5,6- tetramethylcyclo-1-hexene or 1,5,5,6- tetramethylcyclohexene in the solution.... But, I would like to know if 1,5,5,6- tetrameythyl- 1- cyclohexene would also be accepted.

[leilarishwain_3H]

Can someone please explain when you are supposed to use numbers in the middle of a word? For example, prop-2-en-1ol / 2-propen-1-ol.

Thank you!

[Nasir_Ahmed]

I believe you only do that when it involves alkenes or alkynes in order to distinguish where the second or third bond is.

[divya_devineni_2E]

Can someone explain what "sec" is?

[Annie Zhang_ 3C]

I'm a little confused on what cases to use prefixes like iso and neo rather than the normal numbering

I also have this question - although I understand that you use iso- and neo- when you see specific groups, I can't quite understand how to identify them and when to use iso- or neo- as opposed to other naming strategies. Any help would be much appreciated, thanks!

[904621096]

why is there sometimes a number in between the name like hexadecan-1-ol?

[tpat14]

So cis- trans- and E, Z are always interchangeable?

[tpat14]

why is there sometimes a number in between the name like hexadecan-1-ol?

I believe it is there because the OH (alcohol) group is attached to the 1st carbon

[Michael_Phillipi_1I]

Will we be penalized for not including 1 in naming? For example can we just write 2-methyloct-4-enol instead of 2methyloct-4-en-1ol?

[Michael_Phillipi_1I]

Would you put a dash inbetween naming with groups when one ending has a vowel and the start has a vowel? For example, would it be bromooctane or bromo-octane?

[Zulfiqar Lokhandwala 1H]

If it were something like 1-bromooctane I believe you still can write it like that or you can write 1-bromo-octane. Same would apply to 1-bromoethane. I dont think vowels change the naming of the organic molecule

[FaithPigeon_1E]

Will we be penalized for not including 1 in naming? For example can we just write 2-methyloct-4-enol instead of 2methyloct-4-en-1ol?

Because there are other substituents, it is important to describe the location of the alcohol group

[Alexma 3A]

So cis- trans- and E, Z are always interchangeable?

They are interchangeable but the Z and the E must have parenthesis around them, while cis and trans do not need parenthesis

[Alexma 3A]

how do you name substituents on a ring if there are more than 2 substituents?

[Bryan Vega 2E]

how do you name substituents on a ring if there are more than 2 substituents?

Compare each number and select the name with lowest number.

[Diana_OToole_1F]

So cis- trans- and E, Z are always interchangeable?

No, cis/trans is comparing identical groups or the longest chain, but E/Z is based on a priority system. The question will probably ask to label something as either cis/trans OR E/Z. But if it doesn't specify, it's suggested to always use E/Z because it will never fail.

[Aiden_Hsu_1M]

When you name something with an ether substituent in it how do you name it?

[Tycho_Meimban_2B]

When you name something with an ether substituent in it how do you name it?

Because we know that ether is a substituent, you replace the -yl at the end of the subsituent with -oxy. For example, if we have an ethyl substituent with an Oxygen molecule (i.e. -OCH₂CH₃) we name it ethoxy instead.

Hope this helps!

[Michael_Phillipi_1I]

Will we be penalized for not including 1 in naming? For example can we just write 2-methyloct-4-enol instead of 2methyloct-4-en-1ol?

Because there are other substituents, it is important to describe the location of the alcohol group

But isn't that implied? Dr. Lavelle said that you can omit the 1 on other examples.

[Kristina98]

What do the numbers represent?

where the specific functional group or constituent is

[Kristina98]

What do the numbers represent?

where the specific functional group or constituent is

[Kira_Maszewski_1B]

You would use dashes to separate the position of the substituents or functional group from the type of substituent or functional group. Also, we use them to separate the position of a double bond or triple bond. For Example:
3,2-dimethylbutane
2-ethylpent-1-ene --------> 1 represents the carbon that the double bond is on.

[Neha Jonnalagadda 2D]

The dashes are used to separate the numbers from the names.