Evaluative Revision

Including

  • Preparation of organic products
  • Distillation equipment and why it works the way it does
  • Functional groups: Ketone, Aldehyde, Ester and Alcohol
  • Reactions to form Carboxylic acid
  • Why metal carbonates react with acids,type of reaction and products
  • Identifying groups uing IR spectroscopy
  • Identifying cations using n/z values
HideShow resource information

Preparation of organic products (organic synthesis

Organic products: "carbon-based compounds and hydrocarbons. May contain many other elements, including hydrogen, nitrogen and oxygen." ~Wikipedia

Is the process of making a desired product by choosing suitable available reagents and carrying out reactions in a specific order. Each stage in an organic synthesis normally requires three steps; reaction, separation and purification.

  • Reaction: The reaction chosen depends on the available reagents and efficiency. Many organic reactions do not give 100% yield, so the route is chosen which is likely to provide the best yield.
  • Separation: The product is usually mixed with other by-products and unreacted material and needs to be separated in some way. This may be done by filtration, distillation, steam distillation, solvent extraction, chromatography, etc. The method chosen depends largely on the state of the product and the nature of the impurities.
  • Purification: The product may be purified by distillation, recrystallisation, sublimation etc. The final purity is usually established using the melting or boiling temperature of the product. A pure product has a sharp melting/boiling point.
1 of 6

Distillation equipment and why it works the way it

  • Distillation- the separation of one substance from another by evaporation and condensation. The product obtained is called the distillate.
  • Used to eliminate solid impurities from a liquid. Water can be freed of salt or other minerals through this process.
  • Water is boiled in a closed container called a boiler. Vapor evaporating from the surface of the boiling water passes through a pipe leading from the boiler to a vessel called a condenser. The condenser, in turn, opens into a third vessel. The entire apparatus is called a still.
  • In its simplest form, the condenser is a tube surrounded by a larger tube filled with cold water. The water vapor from the boiler never touches the cold water, which cools the vapor as it passes through the inner tube. As the vapor loses its heat, it becomes liquid and flows into the collecting vessel.
  • The process continues until all the water in the boiler has evaporated. Solid impurities that had been in the water remain on the bottom of the boiler.
  • In vacuum distillation, the atmospheric pressure inside the boiler is reduced, allowing the liquid to boil at a lower temperature.
  • In steam distillation, steam is fed into the boiler and turns the substance to be distilled into vapor.
2 of 6

Functional groups: Ketone, Aldehyde, Ester and Alc

ketone (http://0.tqn.com/d/chemistry/1/0/n/3/cogroup.gif)aldehyde (http://0.tqn.com/d/chemistry/1/0/o/3/cohgroup.gif) ester (http://0.tqn.com/d/chemistry/1/0/q/3/coogroup.gif)alcohol (http://0.tqn.com/d/chemistry/1/0/u/3/ohgroup.gif)

  • KETONE c-oo-c
  • simple compound which contains a carbonyl group - a carbon-oxygen double bond. simple in the sense that they don't have other reactive groups like -OH or -Cl attached directly to the carbon atom in the carbonyl group - as you might find, for example, in carboxylic acids containing -COOH.
  • ALDEHYDE -cho
  • simple compound which contains a carbonyl group - a carbon-oxygen double bond. simple in the sense that it doesn't have other reactive groups like -OH or -Cl attached directly to the carbon atom in the carbonyl group - as you might find, for example, in carboxylic acids containing -COOH.
  • ESTER
  • Esters are derived from carboxylic acids. A carboxylic acid contains the -COOH group, and in an ester the hydrogen in this group is replaced by a hydrocarbon group of some kind. This could be an alkyl group like methyl or ethyl, or one containing a benzene ring like phenyl.
  • ALCOHOL -OH
  • Alcohols are compounds in which one or more hydrogen atoms in an alkane have been replaced by an -OH group
3 of 6

Reactions to form Carboxylic acid

  • Primary alcohols and aldehydes are normally oxidised to carboxylic acids using potassium dichromate(VI) solution in the presence of dilute sulphuric acid. During the reaction, the potassium dichromate(VI) solution turns from orange to green.
  • The potassium dichromate(VI) can just as well be replaced with sodium dichromate(VI). Because what matters is the dichromate(VI) ion, all the equations and colour changes would be identical.
  • Primary alcohols are oxidised to carboxylic acids in two stages - first to an aldehyde and then to the acid. We often use simplified versions of these equations using "[O]" to represent oxygen from the oxidising agent. (the R is a hydrogen atom or alkyl group)

(http://www.chemguide.co.uk/organicprops/acids/oxalceq1.gif)

4 of 6

Why metal carbonates react with acids, type of rea

  • acid + metal -> salt + water + carbon dioxide
  • a metal carbonate is a metal that has combined carbon and oxygen. E.g. Copper Carbonate

Acids                              Salts

Hydrochloric acid             Chloride

Sulphuric acid                  Sulphate

Nitric acid                        Nitrate

  • The carbonate will usually fizz and foam when the acid is poured onto it - this is the CO2 being released.
    The equation for sodium carbonate reacting with hydrochloric acid is:
    Na2CO3 + 2HCl → 2NaCl + CO2 + H2O
5 of 6

Identifying cations using n/z values

(http://www.scienceaid.co.uk/chemistry/fundamental/images/massspectrum.jpg)

This spectrum tells us that 23% is magnesium-32, 10% is magnesium-32.5, 46%is magnesium-64 and 21% is magnesium-66. So, multiply each by it's own value and divide by 100.

6 of 6

Comments

No comments have yet been made

Similar Chemistry resources:

See all Chemistry resources »See all Reactions resources »