In today’s lesson, we are going to discuss nomenclature and properties of the following organic functional groups:
1. Carboxylic Acids
2. Alcohols
3. Thiols (Sulfur Alcohols)
4. Ethers
5. Thioethers
6. Esters
see url Carboxylic Acids
Carboxylic acids are a https://semnul.com/creative-mathematics/?p=mwglehms0 carboxyl group in their shape. I have highlighted the carboxyl group below:
When we name these, we name it with the prefix system (which was discussed in a previous post), with substituent rules being the same and all – but there is one difference. We change the ending to Buy Diazepam 20 Mg Uk -oic acid. The carboxyl group is always at the end of the compound, so number the first carbon starting at the carbonyl (the carbon double bonded to oxygen, as I have the #1 labelled there above). Let’s take a look at these examples below, from name to drawing and back:
(a) We number the chain starting from the carbonyl group, which is where I started the first carbon chain numbering from (in red numbers above). This is a 4 carbon chain, which is a “but-” prefix. We name it as an alkane, which is https://technocretetrading.com/5lbeooxa6u butane, but we drop the ‘e’ to get https://luisfernandocastro.com/tunsptze butan-.
(b) There are no substituents that we need to name before the main chain, so we just add the “-oic acid” suffix.
(c) This is here butanoic acid!
Cheap Valium Online Uk Let’s try drawing 4-methylpentanoic acid
(a) First we draw the main chain, which is a “pent” in the name. This prefix indicates a 5 carbon chain
(b) We draw the carboxyl group on carbon #1, because we can see the ending is “-anoic acid.” Sometimes it can be drawn upside down like this, but it doesn’t make a difference
(c) There a methyl group on carbon 4, so we add that in. This is final shape!
We can also have two carboxyl groups in one shape – let’s look at this example below. We have two of the carboxyl groups, so rather than a “-oic acid,” we insert a “di” to get “ https://www.parolacce.org/2024/09/18/zpqd1r0c dioic acid.” The number of carbons is 2 in this chain, so that’s an “ethane.” In this case, we don’t drop the ‘e’ because we have a “di” at the beginning, we won’t have two vowels in a row (eg. ethan https://www.fandangotrading.com/p6e5baooq eoic acid gives us two vowels next to each other which is why we usually drop the ‘e’). We connect ethane + dioic acid to get https://trevabrandonscharf.com/08d813cyk ethanedioic acid.
see url Properties of Carboxylic Acids
Buy Diazepam 5Mg Uk (a) Solubility: Smaller carboxylic acids are soluble in water because they are polar due to the hydrogen bonds in the shape. Larger chains have a larger non-polar area (the hydrocarbon chain) so they are less soluble in polar solvents like water
https://boxfanexpo.com/0jdwp0p33d (b) Boiling Point: Only with carboxylic acids, hydrogen bonding can occur between two molecules to make a dimer. These increase the strength of the van der Waals intermolecular forces, giving a high boiling point. If we compare the boiling points of hexanoic acid (a carboxylic acid) vs. 2-hexanone (a ketone that only has the carbonyl group but not the alcohol), the boiling point of the carboxylic acid is way higher because of the hydrogen bonding within the alcohol (O-H) group.
https://traffordhistory.org/lookingback/oxia247 (c) Odor: Strong odors, for example vinegar (has ethanoic acid) or butter gone bad (has butanoic acid)
https://www.modulocapital.com.br/zr91y5e Alcohols
Alcohols have an “OH” group in their shape. There can be primary, secondary or tertiary alcohols, depending how many other groups are coming out of the carbon that also has the alcohol group on it (or you can count the number of hydrogens on that carbon). If you look at the picture below, a primary alcohol has 2 hydrogens coming out of the red dotted carbon that also has the alcohol group on it. Secondary alcohols have 1 hydrogen coming out of that carbon, and tertiary alcohols have none. Here are examples of primary, secondary and tertiary alchols, with the alcohol groups highlighted:
Let’s try naming this shape:
(a) We first number the longest carbon chain, making sure that the alcohol is included in the main chain, and has the lowest number. This is a 4 carbon chain, and we name it as an alkane but drop the ‘e’. So the prefix is go to link “but” and if we name it as an alkane, it is Buy Roche Diazepam Uk butane. Dropping the ‘e’ gives us “butan-“ I counted right to left to get the alcohol on carbon #2.
(b) We indicate the number the alcohol group is on (carbon 2), and add an “-ol” suffix to indicate we have an alcohol.
(c) Connecting the two parts gives the name of this shape as 2-butanol (or put the number in the middle to get butan-2-ol). This is a secondary alcohol because carbon 2 has two other alkyl groups coming out of it, aside from the OH group. Or if you count the hydrogens, it has 1 hydrogen out of carbon #2.
We can also have two alcohol groups in one shape – let’s look at this example:
(a) We have a 4 carbon chain, and is a “but-“ prefix. We name it as an alkane so that is butane, and we drop the ‘e’ to get “butan-“
(b) We have 2 alcohols in the family, and this is the functional family of the group since we have no other substituents. The suffix of the alcohol family is “-ol”
(c) The alcohol groups are on carbons 2 and 3. We have two of them so we have to use “di” before the “ol.”
(d) Connecting everything together gives 2,3-butandiol! We can also put the numbers in the middle, to get butan-2,3-diol.
Properties of Alcohols
(a) Solubility: Same reasoning as carboxylic acids
(b) Boiling/Melting Point: Higher BP than their respective alkanes (eg. pentanol has a higher BP than pentane) due to hydrogen bonding
(c) Viscosity: Increases as the molecules increases because there are more intermolecular forces in a larger molecule
(d) Polarity: Uses this ranking, with amides having the highest polarity – Amide > Acid > Alcohol > Ketone ~ Aldehyde > Amine > Ester > Ether > Alkane.
(e) Flammability: Flammability is the ability of a chemical to burn or ignite. It decreases as the size of the molecule increases because there are more covalent bonds to break in order to burn the molecule.
Thiols
Naming thiols follow all the same rules as naming alcohols, and a thiol group can also be called a “sulfur alcohol” group. The thiol group is an “SH” group, as the shape below shows. Let’s try to name this shape:
We have a three carbon chain, as I have numbered below:
Name the chain as an alkane first. This gives propane, because the prefix for 3 carbons is “prop.” We don’t drop the ‘e’ here, and we add a “thiol” at the end. We also have to indicate the number that the thiol group is on, which is carbon 2. This gives 2-propanethiol, or propane-2-thiol.
Properties of Thiols
(a) Odor: Strong, sometimes similar to onions and garlic. Lower molar mass thiols have stronger smelly odors. Some smell pleasant, such as roasted coffee or grapefruit scents
(b) Solubility: Not as soluble in water as alcohols due to the absence of hydrogen bonding
Ethers
An ether group is a fused oxygen into a carbon chain. There are a couple different ways to name ethers. Take a look at this example below of an ether:
To name ethers, there are three different methods we can use:
(1) Alkyl Alkyl Ether method:
With the alkyl alkyl ether method, we list the two alkyl groups on either side of the oxygen, numbering outward from it (so the first carbon should be the one closest to the Oxygen) because we have no other substituents to put on a lower number.
They will be in alphabetical order, and then we put the word “ether” at the end of it. This compound has a 2 carbon chain on the left (prefix “eth”) and a 1 carbon chain on the right (prefix “meth”) and putting them together as substituents (suffix of -yl) and alphabetical order (so eth goes before meth) gives ethyl methyl ether.
If it’s the same alkyl group on both sides, like we see below, we put a “di” in front of the name of the substituent. This is a diethyl ether.
(2) Alkoxy method: We can name an ether as an “alkoxy”. The longer/more complex alkyl chain will take the name of the “main chain.”
For this shape above, there is a 2 carbon (ethyl) substituent on the left. The longer chain is on the right, so we name it as an alkane, and it is a 3 carbon substituent, so it is a propane.
Connecting these with the “oxy” method means we drop the “yl” on the shorter substituent (which is the ethyl, so it becomes “eth”) and we add an “oxy” at the end of it to get “ethoxy.” Then add the second, longer substituent to it, to get ethoxypropane.
Sometimes the oxygen is not really “fused” in the chain, but it’s more “hanging off” the chain as a substituent. Let’s look at an example:
Alkoxy groups are lower in priority than alkanes, so I numbered left to right to put the methyl on carbon 2 and the oxygen (alkoxy) group on carbon 3. The main chain is a 4 carbon chain (in yellow), which is butane.
We have a one carbon methyl group on carbon 2 (a 2-methyl) and an alkoxy group (oxygen with the extra 2 carbons on it) coming off of carbon 3 on the main chain. This alkoxy group is an “ethoxy” because we have 2 carbons (prefix “eth”) and the oxygen gives an “oxy” to make “ethoxy.”
Putting them in alphabetical order (ethoxy comes before methyl before ‘e’ before ‘m’) we get 3-ethoxy-2-methylbutane.
(3) Oxa method:
In this method, we count the longest chain and include all the atoms, including both carbon and oxygen. This is a 5 atom chain, so we name it as an alkane. This is pentane, because the prefix for 5 is “pent.” We add an “oxa” before it, and the number of the oxygen which is on atom 3. This is 3-oxapentane.
Properties of Ethers
(a) Odor: Usually pleasant smelling
(b) Phase: Can be gas or volatile liquid at room temperature
(c) Color: Usually colorless
(d) Boiling/Melting Point: Weakly polar and they have lower boiling points when compared to alcohols, due to the absence of hydrogen bonding
(e) Solubility: Solubility in polar solvents like water decreases with higher carbon atoms because they are the non-polar part of the molecule. Because they have an Oxygen, they can hydrogen bond with water molecules and end up having about the same solubility as an isomeric alcohol (an alcohol with the same formula). For example, C2H6O can be a formula for both an alcohol and an ether, and both are soluble in water. But both the alcohol and ether of C4H10O are not soluble in water.
Thioethers (Sulfides)
Thioethers are a combination of thiols and ethers. They are ethers but with a sulfur fused into the ring instead of oxygen. They can also be called sulfides. See this example below. We can name it in three different ways, just like with ethers.
(1) Alkyl Alkyl Thioether: Naming a thioether this way uses the same rules as naming an ether with this method above. But rather than name the alkyl groups and put “ether” at the end, we put “sulfide” at the end. The shape above would be Ethyl Methyl Sulfide.
(2) Alkylthio-: Naming a thioether this way uses the same rules as naming an ether with this method above. But instead of uses “alkoxy” we use “alkylthio.” So the shape above would be named methylthioethane because the longest chain is ethane on the left, which becomes the main chain. The shorter chain on the right with 1 carbon is named as a substituent, which is methyl. Putting them together with “thio” in the middle gives methylthioethane.
(3) -Thio: Naming a thioether this way uses the same rules as naming an ether with this method above. The longest chain of atoms, including sulfur, is 4, as I show below. This is butane. The sulfur comes on carbon 2, and we indicate it use “thio.” So it is a 2-thiobutane.
Properties of Thioethers
(a) Odor: Usually very smelly, but at 30-100 ppm (concentration) they can take on a “sickeningly sweet” smell
(b) Color: Colorless
(c) Phase: Gas at room temperature, liquid under very low temperatures or high pressures
Esters
Esters are similar to ethers, but have a carbonyl group attached right next to the oxygen in the chain. They are named using the suffix “-oate.” Here is an example below, with the “ester” part highlighted:
To name an ester, use the following steps:
(a) Name the chain that does not contain the carbonyl group as a substituent with a -yl ending. For this shape below, that is the right side of the Oxygen in the chain, and it’s a 2 carbon ethyl
(b) Name the chain that does contain the carbonyl group as an alkane, but drop the ‘e’ and add “-oate” as the suffix. For this shape below, it’s the 4 carbon chain on the left side of the Oxygen. The carbonyl oxygen is carbon 1. This is a butane, but dropping the ‘e’ and adding “oate” gives butanoate
(c) The final name is ethyl butanoate. If there are any substituents, name them before each respective chain. (Eg. 1-methylethyl 3-ethylbutanoate)
Properties of Esters
(a) Solubility (in polar solvents, like water): They do not form hydrogen bonds, but they are polar molecules so they are soluble in water. Longer carbon chains have decreasing solubility, due to the non-polar portion of the chain increasing. So esters of low molar mass are a little soluble in water.
(b) Boiling/Melting Point: They do contain polar bonds but because there is no hydrogen bonding within the shape (HB), their boiling points are between that of an alkane (no HB) and an alcohol (HB).