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

Hydrolysing Organic Halogen Compounds. The purpose of this experiment is to find out how the rate of the hydrolysis of an organic halogen compound depends on (1) the identity of the halogen atom (2) the nature of the CH skeleton.

Extracts from this document...

Introduction

Victor Leung 7C (10) Experiment Date: 28TH September, 2006. EXP1 - Hydrolysing Organic Halogen Compounds Aim: The purpose of this experiment is to find out how the rate of the hydrolysis of an organic halogen compound depends on (1) the identity of the halogen atom (2) the nature of the CH skeleton. Principle: The hydrolysis of haloalkanes is an example of nucleophilic substitution in which the carbon halogen bond is replaced with a hydroxyl group. Water molecule is the nucleophile of the reaction while the halide ion departs as the leaving group. The reaction occurs faster with alcohol acting as a common solvent. The ease of leaving of halide ions increase in as the atom becomes bigger, and the bonding length longer. Method: The experiment made use of the product of hydrolysis - halide ions. The halide ions formed could be detected by AgNO3 which forms precipitation. The length of time required is inversely proportional to the rate of reaction. By observing the changes in the test tubes, we could compare the reactivity of the samples. Apparatus and chemicals: * 1-chlorobutane , 1-bromobutane , 1-iodobutane , chlorobenzene; * Secondary Alkyl Halide (2� R-Cl), Tertiary Alkyl Halide (3� R-Cl) * Silver Nitrate (AgNO3) * New Clean Test tubes; * Clock Experiment Procedure and Observations 1. ...read more.

Middle

1-chlorobutane, 1-bromobutane, 1-iodobutane The reaction involved in 1-chlorobutane, 1-bromobutane and 1-iodobutane are very similar, they are all primary haloalkanes and they possess the same hydrocarbon skeleton - butane. Their reaction pathways are also similar. The substrate is favour to SN2 mechanism as it is a primary haloalkane, the carbon atom where the halogen atom is attached to, has two hydrogen attached to it. The molecule is favoured to the backside attack of the SN2 pathway. Steric hindrance is not significant. The reaction rate of the three similar substrates are contrasted by the carbon halogen C-X bonding. The shorter the bond length, the stronger the bond; the stronger the bond the more difficult it is for the successful attack to occur. The bond length depends on (1) the atomic size of the halogen atom and (2) the polarity of the bond. Halogen atoms has an increasing atomic size according to: Cl > Br > I . The covalent bonding is the interaction of the outermost shell of electron between the halogen atom and the carbon atom. The smaller the atomic radius, the halogen atom nucleus will exert a stronger the nuclear attraction to the bonding electrons. Therefore Cl atoms have the strongest covalent bonding when compared with Br and I. ...read more.

Conclusion

The forming of a benzene cation in SN1 reaction is also a very unstable intermediate because it requires the breaking the benzene resonance structure in its formation. This requires a very large activation energy thus its reaction is not favored. Combining the number of disadvantages in the process of hydrolysis of chlorobenzene to phenol, the reaction will only proceed under severe condition with sodium hydroxide as the nucleophile. Notes on Procedure Precautions The test tubes used for this experiment should be completely free of halide ions in order to obtain accurate result while the silver ions form precipitations. The use of alcohol is to act as a common solvent to increase the contact chance of reactants: H2O and the haloalkanes. Its importance is to increase the rate of reaction and obtain reliable results. Results In the experimental results, we see a strange result for the reaction involving the secondary haloalkane, the tube produce no observable result which was expected. This might be due to insufficient temperature for the SN1 reaction to overcome the EA in the rate determining step. The experiment should include a warming step which provides some kinetic energy to the molecules. The manual suggest a water bath at 60�, however, due to lab limitation, this step is skipped, thus the reaction may occur at a very slow rate. The absence of precipitation of 1-chlorobutane might also be related to the low reaction rate. ?THE END? ?? ?? ?? ?? ...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 Acidities of Wine. The purpose of this experiment is to ...

    5 star(s)

    After the final evaporation, the remaining liquid was again made up to 25cm3 with deionised water, ensuring that the evaporating cylinder was thoroughly washed out, to ensure that all of the liquid was transferred. This liquid was then transferred to a beaker, and a magnetic stirrer added, and titrated as above, using the pH meter to record pH against volume.

  2. Preparation of haloalkane. The purpose of this experiment is to prepare 2-chloro-2-methylpropane from ...

    The lower layer (aqueous layer) was then discarded. 9. Sodium hydrogencarbonate solution was added 2cm3 at a time into the separation funnel in order to neutralize any excess hydrochloric acid. 10. The funnel was shaken gently after each addition and the stopper was frequently loosened to release the pressure.

  1. Comparing the rates of hydrolysis of chloro-, bromo- and iodo- alkane

    The reactivity of halo group on the rate of the hydrolysis reaction is: iodo- > bromo- > chloro- The reactivity depend on the bond strength of the C-- X bond, the weaker the strength of the C-- X bond, the more reactive the solution is.

  2. The Importance of Functional Groups and Isomerism in Organic Molecules

    * A gelatinising agent in explosives * A solvent in rubber cement * In cleaning fluids Isomer of Propanone Name of isomer: Propanal, also known as propionaldehyde Type of isomerism: Functional group isomerism, this is because the functional group has changed from being ketone to aldehyde.

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

    This indicated the end point of the reaction. A note of the new burette reading was then recorded. To work out the volume of the solution added a calculation was made whereby the initial reading was subtracted from this end point value.

  2. Qualitative Analysis (A combined approach using spectroscopic and chemical analysis for structural identification of ...

    No observable changes were observed and there were no formation of precipitate. Thus, halogen was absent in both unknown samples. At this stage, we knew that both BS and BL do not contain any nitrogen and halogens. After the solubility test, as we already knew that BS and BL do

  1. Organic Compounds

    The fermentation process takes three days and is carried out at a temperature between 250C and 300C. The ethanol is then obtained by fractional distillation. Sugar (glucose or fructose) � alcohol (ethanol) + carbon dioxide C6H12O6 � 2 CH3CH2OH + 2 CO2 Uses Ethanol is used in the manufacture of alcoholic drinks, e.g.

  2. The aim of this experiment is to investigate the enthalpy change of combustion for ...

    * Light the spirit burner and replace the base of the calorimeter. * Wait for the temperature to rise several degrees while continuously stirring the water. * Extinguish the flame and switch off the suction pump. * Keep stirring for a further minute to ensure that the temperature of the water increases to its true value.

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