• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

Qualitative Analysis (A combined approach using spectroscopic and chemical analysis for structural identification of organic compound)

Extracts from this document...

Introduction

Student Name: Chan Yu Yan Maggie (Applied Biology) 22nd Nov, 2006 Student ID: 50920875 Group: B-2 BCH 2007 Principles of Organic Chemistry Experiment 8: Qualitative Analysis (A combined approach using spectroscopic and chemical analysis for structural identification of organic compound) Introduction In organic chemistry, the idenctification of organic compounds is a problem that is often encountered. As there are numerous of organic compounds of such wide variety in the world, identification is really difficult unless approached in a systematic and logical manner. To solve these problems, both spectroscopic and chemical techniques are useful. The general procedure for the identification of an organic compound consist of preliminary physical test, solubility test, qualitative elemental analysis, chemical characterization tests, spectroscopic analysis, literature search and further experimental comparisons. Objective: To identify the two unknown samples BL (molecular mass: 88.11 g, b.p.:76-78?C) and BS (molecular mass:122.17 g, m.p.:22-23?C) with known b.p or m.p and molecular mass by carry out different examinations, tests and spectroscopic analysis. Materials and Methods Procedure for preliminary physical examination The physical state, colour, shape and size, viscosity and odour of both the unknown solid and liquid were observed and recorded. For the ignition test, 0.1 g of the sample was placed in a porcelain crucible cover and brought to the edge of a flame. It was then heated gently over a low flame and behind a safety shield and eventually heated strongly to accomplish thorough ignition. Its flammability was observed. ...read more.

Middle

For the ignition test, it burned with a blue flame. Qualitative Analysis of Elements For the detection of nitrogen of procedure A, both the BS and BL unknown showed a negative result. No Prussian blue precipitate was present. For the detection of nitrogen of procedure B, both of them also showed a negative result. No red coloration was found. Therefore, both of them do not contain nitrogen. For the detection of halogens, both the BS and BL unknown gave a negative result. No observable changes were observed and there were no formation of precipitate. Thus, halogen was absent in both unknown samples. Solubility test For BS, it does not dissolve in water and HCL, but it dissolves in NaOH and gives a pink colour. It is also not dissolve in NaHCO3. Thus, BS is class A2 which may be phenols or some acids and anhyrides. For BL, it does not dissolve in water, HCL and NaOH, but it dissolves in H2SO4 and gives out a light yellow. Therefore, it is class N which may be alcohol, aldehydes, ketones, esters, ethers, unsaturated hydrocarbons or anhydrides. IR spectroscopy For BS, in the spectrum, there were a broad peak at 3384 cm-1 which indicated the presence of OH group for phenol, a little small peak at 3000 cm-1and peaks occurred at 910-1377 cm-1 indicating there is aromatic ring, peaks at 2852 cm-1 and 2923 cm-1indicating the presence of CH3 and CH2 groups. ...read more.

Conclusion

interfere with our deduction .This might due to the contamination of the unknown compounds or the present of impurities .Moreover, we used chloroform to clean the plate which might not evaporate completely before we put them in the spectroscopy. For improvement, wait for a while after cleaning the salts plates or apparatus used for IR spectroscopy so that the chloroform can fully evaporate in order not to interfere the results. All the unknown samples must handle carefully such as using a new dropper or spoon to take the sample out each time to reduce contamination chance to minimum. More Chemical tests can be done to further confirm the results. For the result of hydroxamate test for carboxylate ester, the first time result was between positive and negative. This might due to the present of impurities or the improper amount of the reactant used. Too much addition of ferric chloride for the last step of the test might also interfere with the result colour as it is yellow in colour. For improvement, make sure all the apparatus used are clean and the test can be done for one or two more times. Proper amount of the reactant is used and at most 3 drops of ferric chloride are added at the last step so that it will not cover the resultant colouration. Conclusion The given unknown solid BS with molecular mass of 122.17 g and m.p. of 22-23?C was 2, 4-dimethylphenol and the unknown liquid BL with molecular mass 88.11 g and b.p. of 76-78?C was ethyl acetate. 1 ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our AS and A Level Organic Chemistry section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related AS and A Level Organic Chemistry essays

  1. Marked by a teacher

    Experiment to determine the ethanol content of wine

    5 star(s)

    start at 0.5cm3 and distilled water 49.5cm3 , with the quantity of ethanol increasing by 0.5cm3 each time, while the volume of distilled water decrease at the same rate to alter the ethanol concentration. However, this would have created a much larger uncertainty, as the uncertainty in the ethanol would be 10% it's total value.

  2. Marked by a teacher

    Reactions of aldehydes and ketones. The purpose of this experiment is to compare ...

    5 star(s)

    The reaction mechanism of this reaction is as follow: (Where Nuc represents the nucleophilic species which, in this case, is hydrogensulphite ion) The final product was an alcohol. For the 2nd step of the reaction, water is already sufficient to provide the H+ ion as methoxide ion is more basic

  1. Determination of the formula of Hydrated Iron (II) Sulphate crystals

    down to 0.01g so half of that is 0.005 and you divide this by the measurement read using that device. This is then multiplied by 100 to get a percentage: For the top pan balance Measurement uncertainty percentage= (0.005/mean number)x 100 Crucible (alone)

  2. Find the enthalpy change of combustion of a number of alcohol's' so that you ...

    To improve this I could have used a more accurate thermometer, which is measured to the nearest O.10C and leave it in the water for 5 minutes to get a true initial temperature and to minimise error. This would improve the value for both the enthalpy change of combustion and

  1. the analysis of aspirin tablet

    Number of mole of NaOH used to hydrolyse the acetylsalicylic acid: = 0.02537312 mol. - 0.02143 mol. = 0.00394312 mol. CH3.COOC6H4.COOH + 2NaOH � CH3.COONa + HO.C6H4.COONa + H2O Mole ratio of CH3.COOC6H4.COOH to NaOH = 1:2 Number of mole of NaOH = 0.00394312 mol.

  2. Chemical properties of Ethanol & Phenol

    Reaction with bromine water Br2 decolourized readily in presence or absence of light, which indicates that this is not a free radical substitution reaction. A white precipitate is formed. Reaction with 'neutral' FeCl3 The colour of FeCl3 changes from yellow to violet.

  1. Hydrolysing Organic Halogen Compounds. The purpose of this experiment is to find out ...

    Examples of the hydrocarbon skeleton affecting reaction rates will be discussed later on when explaining the reaction of chlorobenzene.

  2. The aim of this experiment is to produce Aspirin. This is an estrification in ...

    Hydroxide1.0 mol dm-3 - This will hydrolyse the aspirin into salicylic and acetate ions * Volumetric flask 250 cm3 - This is used to mix up solutions accurately. * Distilled Water - This is used to make up the correct solutions and to wash equipment.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work