Ch. 1: Nomenclature Flashcards
what are the 5 steps to IUPAC naming?
- identify the longest carbon chain containing the highest-order functional group
- number the chain
- name the substituents
- assign a number to each substituent
- complete the name
Explain step 1 of the IUPAC naming system: identify the longest carbon chain containing the highest-order functional group (2)
- this will be the parent chain and will be used to determine the root of the name
- the highest-priority functional group will provide the suffix
what happens if, when identifying the longest carbon chain in IUPAC naming, that there are two or more chains of equal length?
then the more substituted chain gets priority as the parent chain
explain step 2 of the IUPAC naming system: number the chain (2)
the carbon numbered 1 will be the one closest to the highest-priority functional group
if all the functional groups all have the same priority, numbering the chain should make the numbers of the substituted carbons as low as possible
the more oxidized the carbon, the higher or lower priority it has in the molecule?
higher priority it has in the molecule
with what does oxidation state increase and decrease?
increases: with more bonds to heteroatoms (atoms besides carbon and hydrogen)
decreases: with more bonds to hydrogen
how are rings numbered?
just like straight chains
starting at the point of greatest substitution, continuing in the direction that gives the lowest numbers to the highest priority functional groups
what do you do if there is a tie between assigning priority in a molecule with double and triple bonds?
the double bond takes precedence
explain step 3 of the IUPAC naming system: name the substituents (2)
- substituents = functional groups that are not a part of the parent chain
- a substituents name will be placed at the beginning of the compound name as a prefix, followed by the name of the longest chain
how are carbon chain substituents named? (3)
- like alkanes
- -yl replaces -ane
- n- indicates that this is “normal” (this will only be added in sometimes)
what do we do with naming if there are multiple substituents of the same type? (2)
use the prefixes
di, tri, and tetra, etc. to indicate this
these are usually included right before the substituents name
explain step 4 of the IUPAC naming system: assign a number to each substituent (2)
- pair the substituents that you have named to the corresponding numbers in the parent chain
- multiple substituents of the same type will get both the di-,tri-, and tetra- prexies and also a carbon number designation – even if they are on the same carbon
explain step 5 of the IUPAC naming system: complete the name (3)
- always begin with the names of the substituents in alphabetical order, with each substituent preceded by its number (ignore hyphenated prefixes like di, tri, tetra, n, or tert while alphabetizing, but keep other roots like iso, neo, or cyclo)
- then the numbers are separated form each other with commas, and from words with hyphens
- finally, we finish the name with the name of the backbone chain, including the suffix for the functional group of highest priority
defn: hydrocarbons
compounds that contain only carbon and hydrogen atoms
how are alcohols different from hydrocarbons?
they contain at least one -OH group, which lends them additional reactivity
defn: alkanes
simple hydrocarbon molecules with the following formula
what are the names of the first 4 alkanes?
how do you name alkanes after that?
- methane (1 carbon)
- ethane (2 carbons)
- propane (3 carbons)
- butane (4 carbons)
after that, they have a simple naming pattern with the Greek root describing the number of carbons PLUS -ane (i.e. pentane, hexane, heptane, etc.)
defn + naming: alkyl halides
alkyl halides are alkanes with halogens as substituents
indicated by a prefix: fluoro-, chloro-, bromo-, or iodo-
defn: alkene, alkyne
simple hydrocarbon molecules like alkanes BUT
-ene = double bond
-yne = triple bond
how are alcohols named? (2)
- by replacing the -e at the end of the name of the corresponding alkane with -ol
- the chain is numbered so that the carbon attached to the hydroxyl group (-OH)
why does the hydroxyl group take precedence over multiple bonds in alcohols?
because of the higher oxidation state of the carbon
how are alcohols name if the -OH is not the highest priority functional group?
then it is named as a hydroxyl substituent (hydroxy–)
alcohols are often referred to by their common names, rather than their IUPAC names, what is an example?
ethyl alcohol (rather than ethanol)
isopropyl alcohol (rather than 2-propanol)
defn + naming: diols/glycols
alcohols with two hydroxyl groups
- the entire hydrocarbon name is preserved, and -diol is added
- one must number each hydroxyl group
defn: geminal vs. vicinal diols
GEMINAL: diols with hydroxyl groups on the same carbon
VICINAL: diols with hydroxyl groups on adjacent carbons
mnemonic: geminal vs. vicinal diols
VICINal diols are in the VICINity of each other (on adjacent carbons)
GEMINal diols - like the GEMINi twins - are paired on the same carbon
what is an aka for geminal diols?
why are geminal diols not commonly seen?
aka: hydrates
because they spontaneously dehydrate (lose a water molecule) to produce carbonyl compounds with the functional group C=O
what is the commonality between aldehydes and ketones?
two classes of molecules that contain a carbonyl group
defn: carbonyl group
carbon double-bonded to an oxygen
what is the main differentiating factor between aldehydes and ketones?
they differ in the placement of the carbonyl group
aldehydes are chain-terminating (they appear at the end of a parent chain)
ketones are found in the middle of carbon chains
do aldehydes and ketones have any leaving groups connected to the carbonyl carbon?
no, they are only connected to alkyl chains (or hydrogen atoms for aldehydes)
char: aldehydes (2)
- have a carbonyl group found at the end of the carbon chain
- it is generally attached to carbon number 1 because it is a terminal functional group that takes precedence over many others
how are aldehydes named? (2)
- by replacing the -e of the parent alkane with -al
- when the aldehyde is at position 1 (usual) we do not include this number in the chemical name
what are methanal
ethanal
and
propanal usually referred to as?
methanal = formaldehyde
ethanal = acetaldehyde
propanal = propionaldehyde
char: ketones
contain a carbonyl group somewhere in the middle of the carbon chain
how are ketones named? (3)
- we will always have to assign a number to the carbonyl carbon when naming ketones (except propanone, which must have the ketone on carbon 2 by default)
- named by replacing the -e in the name of the parent alkane with -one
- commonly named by listing the alkyl groups in alphabetical order, followed by ketone
what is the smallest possible ketone?
acetone
how do we name aldehydes and ketones when we have a more complex molecule with a higher-priority group that takes precedence over the carbonyl?
we name the aldehydes and the ketones as substituents, using the prefix oxo-
sometimes ketones may also be indicated with the prefix keto-
explain: naming convention of naming carbons relative to the carbonyl group (3)
- the carbon adjacent to the carbonyl carbon is indicated by alpha
- the successive carbons are referred to as beta, gamma, and delta carbons
- this applies on both sides of the carbonyl in the same fashion, so the carbons on both sides of a ketone are considered alpha carbons
char: carboxylic acids (2)
- contain both a carbonyl group (C=O) and a hydroxyl group (-OH) on a terminal carbon
- terminal functional groups, so the associated carbon is usually numbered 1
what is the most oxidized functional group on the MCAT?
carboxylic acids (with 3 bonds to oxygen)
how are carboxylic acids named?
replace the -e at the end of the name of the parent alkane with -oic acid
what are the common names for the following carboxylic acids:
methanoic acid
ethanoic acid
propanoic acid
methanoic acid = formic acid
ethanoic acid = acetic acid
propanoic acid = propionic acid
what are the three carboxylic acid derivative functional groups?
- esters
- amides
- anhydrides
char: esters
the hydroxyl group (-OH) is replaced with an alkoxy group (-OR, where R is a hydrocarbon chain)
how are esters named?
- based on the naming conventions for carboxylic acids
- the first term is the alkyl name of the esterifying group (think of this as an adjective describing the ester, based on the identity of the alkyl (R) group)
- the second term is the name of the parent acid with -oate replacing the -oic acid suffix
char: amides (2)
- the hydroxyl group is replaced by an amino group (nitrogen-containing group)
- can be more complex because the amino nitrogen can be bonded to 0-2 alkyl groups
how are amides named? (3)
- similarly to esters, except the suffix becomes -amide
- substituents attached to the nitrogen atom are labeled with a N- (indicates that this group is bonded to the parent molecule via a nitrogen molecule)
- these substituents are included as prefixes in the compound name and are not numbered
char: anhydrides (2)
- formed from two carboxylic acid molecules, during which one water molecule is removed
- many are cyclic
why are many anhydrides cyclic?
this may result from the intramolecular dehydration of a dicarboxylic acids
how are anhydrides named? (2)
- by replacing acid with anhydride in the name of the corresponding carboxylic acid if the anhydride is formed from only one type of carboxylic acid
- if the anhydride is not symmetrical, both carboxylic acids are named (without the suffix acid) before anhydride is added to the name
when do you use a functional group’s prefix vs. suffix?
suffix: functional group is the highest-priority group in the molecule
prefix: functional group is a substituent
what is functional group priority correlated with?
oxidation state
prefix and suffix: carboxylic acid
carboxy-
-oic acid
prefix and suffix: anhydride
alkanoyloxycarbonyl-
anhydride
prefix and suffix: ester
alkoxycarbonyl-
-oate
prefix and suffix: amide
carabmoyl- or amido-
-amide
prefix and suffix: aldehyde
oxo-
-al
prefix and suffix: ketone
oxo- or keto-
-one
prefix and suffix: alcohol
hydroxy-
-ol
prefix and suffix: alkene
alkenyl-
-ene
prefix and suffix: alkyne
alkynyl-
-yne
prefix and suffix: alkane
alkyl-
-ane
what is the priority from highest to lowest of 10 orgo functional groups?
- carboxylic acid
- anhydride
- ester
- amide
- aldehyde
- ketone
- alcohol
- alkene
- alkyne
- alkane
(alkenes and alkynes are tied for 8th except in cyclic compounds, where alkenes are higher)