As Many Organic Reactions That I Could Cover In Two Hours

Alternatively titled, organic mechanisms cheat sheet. This was a real challenge and of course the detail isn’t there, but I have posts on combusting alkanes, fractional distillation/cracking of the alkanes, halogenoalkanes, organic nomenclature, basic alkanes and halogenoalkane nucleophilic substitution to give you some extra knowledge! And yes – I know some of these aren’t “mechanisms” in the sense of the curly arrow kind.

Halogenoalkanes

[1] Mechanism: free-radical substitution

This reaction involves atoms being replaced by other atoms (in this case, free-radicals). Free radicals have a single unpaired electron, formed if a bond splits evenly and each atom gets one of the two electrons (called homolytic fission).

Examples: chlorination of methane, bromination of methane etc.

Process

Beginning with initiation (1), chlorine-chlorine covalent bonds break symmetrically by absorbing UV light, forming free radicals that have an unpaired electron in the outer shell that makes them particularly reactive.

The second step is propagation (2), where the free radicals react with methane molecules to form hydrogen chloride gas and leaving a methyl free radical which then goes on to react with a second chlorine molecule to form chloromethane and another free radical (3). This continues in a chain reaction.

Termination must occur to stop the chain reaction. This can happen several ways. In the top reaction of (4), chlorine can reform but would not terminate the reaction since UV light just breaks it down again. Another option is the two free radicals forming a chloromethane or forming ethane (C2H6, shown structurally in the diagram).

Product: halogenoalkane

Overall Equation: CH4 + Cl2 -> CH3Cl + HCl

Conditions: UV light, halogen (usually from a CFC), alkane

[2] Mechanism: nucleophilic substitution by a hydroxide ion

In this reaction, the polar C-H bond is susceptible to nucleophilic attack by the nucleophilic ion hydroxide. A nucleophile is an electron pair donor. The reaction can also be called a hydrolysis reaction since it breaks chemical bonds with hydroxide ions.

Example: bromoethane and sodium hydroxide

Process

This is how the mechanism for this would be drawn. Here’s what’s happening – the lone pair on the hydroxide ion is attracted to the slightly positive carbon. Since it cannot make five bonds, when the nucleophile makes the bond, the bond between the C-Br “breaks” and bromine takes the electron to become a halide ion. Remember, curly arrows show the electron movement. The halide then combines with the sodium ions to form sodium bromide.

Product: alcohol

Overall equation: CH3CH2Br + NaOH -> CH3CH2OH + NaBr

Conditions: aqueous sodium or potassium hydroxide, refluxed (continually boiled and condensed), halogenoalkane dissolved in ethanol

[3] Mechanism: nucleophilic substitution by a cyanide ion

In this reaction, the polar C-H bond is susceptible to nucleophilic attack by the nucleophilic ion cyanide (C triple bonded to H). A nucleophile is an electron pair donor.

Example: bromoethane and potassium cyanide

Process

 This is how the mechanism for this would be drawn. Here’s what’s happening – the lone pair on the cyanide ion is attracted to the slightly positive carbon. Since it cannot make five bonds, when the nucleophile makes the bond, the bond between the C-Br “breaks” and bromine takes the electron to become a halide ion. Remember, curly arrows show the electron movement and in this reaction, there is an extra carbon added. This can be confusing and I’ve added just a triple bond to the second carbon before, but that is wrong. The halide then combines with the potassium ions to form potassium bromide.

Product: nitrile

Overall equation: CH3CH2Br + KCN -> CH3CH2CN + KBr

Conditions: aqueous potassium cyanide, refluxed (continually boiled and condensed), bromoethane dissolved in ethanol

[4] Mechanism: nucleophilic substitution by an ammonia molecule

In this reaction, the polar C-H bond is susceptible to nucleophilic attack by the nucleophilic ion ammonia (ammonia can donate a pair of electrons). However, it is a neutral molecule. This mechanism has a few stages.

Example: bromoethane and ammonia

Process

This is how the mechanism for this would be drawn. Here’s what’s happening – the lone pair on the ammonia is attracted to the slightly positive carbon. Since it cannot make five bonds, when the nucleophile makes the bond, the bond between the C-Br “breaks” and bromine takes the electron to become a halide ion. Remember, curly arrows show the electron movement. This is shown by the first step.

The nitrogen becomes positive, with four bonds. Another ammonia molecule is attracted to the hydrogen and removes it from the intermediate stage (remember, this happens instantly and is only in this stage for a very short amount of time) to become an ammonium ion. The product left over is a amine, and the ammonium ion reacts with the bromine to form NH4Br.

Product: amine (primary, secondary or tertiary; primary is obtained if a concentrated solution of ammonia is used since further substitution can occur from the lone pair on the amine molecule).

Overall equation: CH3CH2Br + 2NH3 -> CH3CH2NH2 + NH4Br

Conditions: concentrated ammonia in excess, sealed container under pressure, bromoethane dissolved in ethanol

[4] Mechanism: elimination reaction by a hydroxide ion

Hydroxide ions can act as nucleophiles or electrophiles depending on what solution they are in. In ethanol, hydroxide ions act as a base so accept protons to form water. Elimination reactions are where small molecules are removed from organic compounds.

Example: bromopropane and ethanolic solution of potassium hydroxide

Process

 This is how the mechanism for this would be drawn. Here’s what’s happening – the hydroxide accepts a proton (a hydrogen atom) so a carbon-carbon double bond forms between the carbon that just had a hydrogen taken away and the one next to it. This happens to a carbon adjacent to the C-Br bond, since the Br is then removed as a halide ion upon the formation of the double bond. The hydrogen that has been taken away forms water and the product left over is an alkene

Product: alkene

Overall equation: CH3CHBrCH3 + KOH (in ethanol) -> CH2CHCH3 + + H2O + KBr

Conditions: ethanolic solution of potassium hydroxide, bromoethane dissolved in ethanol

Alkenes

[1] Reaction: addition polymerisation

Alkenes react with other alkenes to form polymers, which make up plastics. Polymers made from an addition process are called addition polymers and they’re pretty simple, named after the alkene they form, e.g. ethane forms poly(ethene).

Example: polyethene

Process

Polymers are repeating chains of carbon atoms. The unit that repeats is the monomer, e.g. ethene.

Product: polymer

Overall equation: n[CH2CH2] -> [CH2CH2]n

Good to know: addition polymers are unreactive since they have no C=C bond, so are good inert materials such as insulators or packaging.

[2] Mechanism: electrophilic addition reactions of hydrogen bromide

Hydrogen bromide is a polar electrophile (proton acceptor). The double bond has an area of high electron density so electrons move from the double bond to the hydrogen of the hydrogen bromide.  

Example: ethene and hydrogen bromide

Process 

This is how the mechanism for this would be drawn. Here’s what’s happening – the electrons move from a delta negative region to a delta positive region (the hydrogen). Electrons then move from the H to the Br, which becomes a halide ion. Now that one carbon is bonded to a hydrogen, the remaining carbon is a carbocation (a positively charged carbon). The halide ion, with a negative charge, is then attracted to the positive charge. The double bond has been broken and the HBr has been added across the double bond.

Product: halogenoalkane

Overall equation: CH2CH2 + HBr -> CH3CH2Br

Conditions: can happen even at temperatures below room temp

[3] Mechanism: electrophilic addition reactions of concentrated sulfuric acid

Concentrated sulfuric acid is a polar electrophile (proton acceptor). The double bond has an area of high electron density which means an electrophilic addition can take place.

Example: ethene and sulfuric acid

Process

This is how the mechanism for this would be drawn. Here’s what’s happening – the electrons move from a delta negative region (double bond) to a delta positive region (the hydrogen). Electrons then move from the H to the O, which becomes a hydrogen sulfate ion. Now that one carbon is bonded to a hydrogen, the remaining carbon is a carbocation (a positively charged carbon). The sulfate ion, with a negative charge, is then attracted to the positive charge on the carbocation. The double bond has been broken and the H2SO4 has been added across the double bond.

Product: akyl hydrogensulfate

Overall equation: CH2CH2 + H2SO4 -> CH3CH2(H2SO4)

Conditions: can happen even at temperatures below room temp

[4] Mechanism: electrophilic addition of bromine

There is no difference in charge across Br2, but it is still an electrophile. The reaction will be coloured since bromine is a distinct brown/orange.

Example: ethene and bromine

Process

This is how the mechanism for this would be drawn. Here’s what’s happening – when the bromine moves closer to the double bond, it gets a slight induced dipole. One bromine then takes the electrons and the electrons from the Br-Br bond go to the end bromine. This then has a lone pair to be attracted to the carbocation.

Product: halogenoalkane

Overall equation: CH2CH2 + Br2 -> CH2BrCH2Br CH2

Conditions: bromine bubbled through alkene, absence of light, temperature below room temp.

Alcohols

[1] Reaction: oxidation

Oxidation is simply the use of an oxidising agent. A primary alcohol is oxidised to produce an aldehyde, then further oxidised to a carboxylic acid. A secondary alcohol is only oxidised to a ketone. A tertiary alcohol is not oxidised.

Process

Primary alcohols lose two hydrogen atoms, one from the O-H group and one from the fully saturated carbon. In the second oxidation, an oxygen is added the remaining carbon.

Secondary alcohols lose a hydrogen to form a ketone which cannot be oxidised further. Tertiary alcohols cannot be easily oxidised since they do not have two hydrogen atoms bonded to the carbon bonded to the –OH group.

Product: aldehyde, carboxylic acid, ketone

Conditions: Primary – oxidising agent in excess to produce a carboxylic acid and refluxed mixture, or distilled off product and alcohol in excess to get the aldehyde. Secondary – refluxed gently with an excess of oxidising agent.

Good to know: Acidified potassium or sodium dichromate (V) is good at oxidising alcohols. The dichromate ion CrO7 2-, is orange and gets reduced to the green chromium(III) ion, Cr3+ when the alcohol is oxidised.

[2] Mechanism: elimination reaction with concentrated sulfuric acid

This reaction can be called a dehydration reaction since a molecule of water is eliminated.

Process

The mechanism above is very simplified since the one for sulfuric acid is fairly complicated. Here’s what’s going on – the oxygen in the –OH group has a lone pair which donates electrons to a H+ ion (usually on the end of a H2SO4 molecule). This means A (which would be the oxygen on a hydrogen sulfate ion) takes the electrons in the bond. The water is then lost from the molecule, forming a carbocation. This then means the hydrogen sulfate (A) ion can remove the H+ ion from the carbocation and the double bond can form between the two carbons.

Product: alkene

Overall equation: CH3CH2OH + H2SO4 -> CH2CH2 + H2O + H2SO4

Conditions: concentrated sulfuric acid catalyst 170 degree temperature, or by passing alcohol vapour over a heated (Al2O3) aluminium oxide catalyst at 600 degrees.

HAPPY STUDYING!

How to Get Smooth Glowing Skin NATURALLY!

Alright this post isn’t going to be a new low cal recipe or a workout routine. In fact, this is going to be aimed towards the self care/beauty side of things, because alongside a healthy diet and exercise it is important that you still take care of your skin. A clean diet will take you pretty far in beautifying your hair, skin and nails, however there are still some steps you can do to pamper yourself and go that extra mile when you feel like it. I’m going to share my favorite ways to get smooth and glowing skin the natural way!

1. Do your skincare routine morning and night. Make sure you wash your face and moisturize twice a day. If you have oily skin or your skin got a little grimy from sweating during the day then just rinse it off with some water and pat it dry. Your skincare routine also doesn’t have to be some ridiculous 8 step Korean skincare ritual. All you really gotta do is wash your face and moisturize it pick a brand that is vegan, cruelty free, uses all natural ingredients, and uses organic ingredients. I highly recommend the brand Andalou or Avalon Organics, because they don’t put harmful chemicals in their products that are going to make you break out. (not sponsored, just saying from personal experience lol)

2. Exfoliate. If you feel like going that extra mile and you feel like just a regular wash isn’t going to do the job then go ahead and grind up a handful of oats in a blender and then wet the oat flour in your hands a bit and then use that to exfoliate your face after you have washed it. Oatmeal is great for sensitive skin and this is great if you get a rough or bumpy texture on your skin or if it looks a little dull. Your skin is going to feel so smooth! Don’t forget to moisturize afterwards.

3. Stop wearing makeup! This step is the most important. I know it’s going to be hard but it feels amazing to be comfortable and feel beautiful in your natural skin. Don’t let society or men make you think you need to wear it. That stuff is full of chemicals and carcinogens that are hormone disruptors and they’re awful for your skin or body! Stop funding those evil makeup companies that thrive off of your insecurities. I promise you, you are beautiful without it. I use to cake my face everyday and it only took a month or two for my skin to go back to normal and for me to feel completely fine without makeup. All my breakouts disappeared when I quit applying makeup, because I no longer had all that gunk and chemicals clogging my pores.


All Natural Makeup Routine to Be a Glowing Goddess:

  • follow your normal skincare routine and keep your skin bare
  • brush through your eyebrows and eyelashes with an old mascara wand a little bit of coconut oil or aloe vera gel
  • mix some beetroot powder and water or oil and use that as a cheek tint or lip tint
  • make your lips glossy with coconut oil
  • use plain cocoa powder for contour if you really want to
  • dab some jojoba oil on the paces you normal highlight your face
  • use a mixture of rosewater, water, a 1-2 drops of peppermint oil in a spray bottle or old setting spray bottle and spritz that on whenever you want a little pick me up
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I’m a revert muslimah currently living in an emotionally, mentally and sometimes extremely physically abusive home and am currently trying to sell homemade beeswax hand salve to build a little savings.

All my hand salves are homemade, organic, cruelty free and made with only five ingredients. It comes in a small range of smells rn: Jasmine, Rose Patchouli, Lavender Sage, Vanilla, Lilac, Freesia and Gardenia. I’m hoping to add more flavours if I can sell my hand salve, iA.

Please consider buying some and reblogging and sharing the link to my Etsy shop.