#alkane

Before proceeding on the steps on how to correctly name and identify alkanes, alkanes should be defined first. Alkanes are hydrocarbons which can only form a single bond unlike alkenes and alkynes which can form double and triple bonds respectively. The IUPAC Nomenclature are the guidelines that are needed to be followed in order to name the alkanes. Take note that the first ten alkanes should be memorized because most of them appear in different IUPAC names. The IUPAC system requires to have names for the unbranched chains and next will be the names for the attached simple alkyl groups. Alkyl groups are named by replacing the suffix "-ane" to "-yl".

Here are the most common alkyl groups:

                                                        source

And now, we can finally proceed to the IUPAC rules regarding alkane nomenclature. The process begins with:

1. Find the longest chain of the carbon atoms as this will give you the name of the parent chain.

Example:

In the figure below, the longest chain is six carbons therefore the parent chain is hexane.

2.  If two chains have the same number of carbons, choose the chain with the most substituents.

3. Number the carbons in the chain starting from the end nearest the first substituent.

Example:

In this structure, we will name the carbons from left to right because is it nearer to the first substituent.

4. If there are substituents that are the same number of carbons in from either end, start the numbering from the end nearest the next substituent

5. Multiplying prefixes are used when a substituent appears more than once. There are also no spaces in the final name.

Example:

There are three instances of the methyl substituent in this alkane therefore it will be called trimethyl.

6. Halogen substituents are given priority in naming

*Lapis tries to comfort Shorai after the event that just took place

Shorai: I....I....I just wanted to help. I'm sorry for scaring. I don't want anybody to feel trapped because of me. I'm sorry I'm sorry I'm sorry (etc)

*Shorai's stone starts to flicker again with light

Unfortunately, if you’re sitting your A Level chemistry exam, you need to know a little more than the basic properties of alkanes outlined in my last post. Luckily though, this post takes you through fractional distillation and the two types of cracking - isn’t that convenient?

Crude oil contains carbon compounds formed by the effects of pressure and high temperature on plant and animal remnants. It is viscious, black and found in rocks beneath the earth’s surface. It is a mixture of mainly alkane hydrocarbons which are separated by a process called fractional distillation. Crude oil is essential because it is burned as a fuel and each fraction has different properties e.g. diesel, petrol, jet fuel.

Fractional distillation is the continual evaporation and condensation of a mixture which causes fractions to split due to a difference in boiling point. It is important to note that fractional distillation does not separate crude oil into pure compounds but rather less complex mixtures. Fractions are groups of compounds that have similar boiling points and are removed at the same level of a fractionating column.

The first step in this process is to heat crude oil in a furnace until some changes state from a liquid to a vapour. This mixture goes up a fractionating tower or column which is hotter at the bottom than the top and reaches a layer which is cool enough to condense and be collected. Shorter chain molecules are collected at the top where it is cooler since they have lower boiling points.

As you go down the fractionating column, bear in mind that: the column temperature increases, the boiling point increases, the number of carbon atoms increases and the strength of the Van der Waals’ between molecules increases.

Different fractions have different usefulnesses and often, it is the fractions with lower boiling points and shorter chains which are much more purposeful. Therefore there needs to be a process to getting shorter chains because they are the least abundant in crude oil samples. To meet demand, long chain molecules that are less useful are broken down into shorter chain molecules. This is done by cracking.

Cracking is a process where long chain hydrocarbon molecules are broken down into shorter chain molecules which are in high demand. This can be done one of two ways - thermal or catalytic.

Thermal cracking involves heating long chain alkanes to high temperatures - usually between 1000 - 1200K. It also uses high pressures up to 70atm and takes just one second. It only needs a second because the conditions could decompose the molecule completely to produce carbon and hydrogen instead. The conditions produce shorter chain alkanes and mostly alkenes.

A typical equation for this:

Decane -> octane + ethene

C10H22 -> C8H18 + C2H4

Catalytic cracking also breaks down long alkanes by heat under pressure using the presence of a zeolite catalyst. Temperature used is approx. 800-1000K and the pressure is often between 1-2 atm. Zeolite is an acidic mineral with a honeycomb structure, made from aluminium oxide and silicion dioxide. The honeycomb structure gives the catalyst a larger surface area which increases ROR. Factories which catalytically crack are often operated continuously for around 3 years at a time and produce branched alkanes, cycloalkanes and aromatic compounds.

You need to be able to compare the conditions of catalytic and thermal cracking for the A Level exam. Know that thermal cracking has a high temperature and pressure, a short duration, no catalyst and produces a high percentage of alkenes and some short chain alkanes. Catalytic uses a catalyst, a high temperature, a low pressure and produces aromatic hydrocarbons and motor fuels.

SUMMARY

Crude oil contains carbon compounds formed by the effects of pressure and high temperature on plant and animal remnants. I It is a mixture of mainly alkane hydrocarbons which are separated by a process called fractional distillation.

Fractional distillation is the continual evaporation and condensation of a mixture which causes fractions to split due to a difference in boiling point. 

It is important to note that fractional distillation does not separate crude oil into pure compounds but rather less complex mixtures.

Fractions are groups of compounds that have similar boiling points and are removed at the same level of a fractionating column.

The first step in this process is to heat crude oil in a furnace until some changes state from a liquid to a vapour. This mixture goes up a fractionating tower or column which is hotter at the bottom than the top and reaches a layer which is cool enough to condense and be collected. Shorter chain molecules are collected at the top where it is cooler since they have lower boiling points.

As you go down the fractionating column, bear in mind that: the column temperature increases, the boiling point increases, the number of carbon atoms increases and the strength of the Van der Waals’ between molecules increases.

Fractions with lower boiling points and shorter chains are much more purposeful but are the least abundant in crude oil samples. To meet demand, long chain molecules that are less useful are broken down into shorter chain molecules. 

Cracking is a process where long chain hydrocarbon molecules are broken down into shorter chain molecules which are in high demand. 

Thermal cracking involves heating long chain alkanes to high temperatures - usually between 1000 - 1200K. It also uses high pressures up to 70atm and takes just one second. It only needs a second because the conditions could decompose the molecule completely to produce carbon and hydrogen instead. The conditions produce shorter chain alkanes and mostly alkenes.

Catalytic cracking also breaks down long alkanes by heat under pressure using the presence of a zeolite catalyst. Temperature used is approx. 800-1000K and the pressure is often between 1-2 atm. Zeolite is an acidic mineral with a honeycomb structure, made from aluminium oxide and silicion dioxide. The honeycomb structure gives the catalyst a larger surface area which increases ROR. 

You need to be able to compare the conditions of catalytic and thermal cracking for the A Level exam. Know that thermal cracking has a high temperature and pressure, a short duration, no catalyst and produces a high percentage of alkenes and some short chain alkanes. Catalytic uses a catalyst, a high temperature, a low pressure and produces aromatic hydrocarbons and motor fuels.

My professor in first-semester organic chemistry was so helpful that he made “cheat sheets” for us. Bless his heart, I work with him now and he’s the best in the department here. So below I posted the four* roadmaps that relate to the first semester of organic chemistry.

Alcohol Synthesis Roadmap

Covers the different synthesis on alcohols and at the bottom right-hand corner introduces ether synthesis.

Alkyne Synthesis Roadmap

Alkene Synthesis Roadmap

Epoxide Synthesis Roadmap

This article was written by Follow Taylor Dart is an individual investor with over 16 years of trading experience, with his primary focus being precious metals developers, producers and royalty/streaming companies. Taylor leads the investing group Alluvial Gold Research, where he offers portfolios with entry/exit points, Buy/Sell alerts, and proprietary sentiment indicators for gold and silver…