experiment conducted was on neutrophilic reaction

The neutrophilic reaction was the subject of the experiment. The introduction, tools and materials, experimental procedure, findings, calculations, discussion, and conclusion make up this paper. The background information on the neutrophilic substitution process, which is crucial for this experiment, is provided in the introductory section. An overview of the tools and substances utilized in this study can be found under the equipment and reagents section. The methods that were taken to successfully get the results are outlined in great depth in the experimental protocol. The calculation provides a thorough analysis of the study which aids in understanding the concepts of the process. In both inorganic and organic chemistry, nucleophilic reaction (substitution) is one of the chemical processes where the electron-rich nucleophile selectively attacks or bonds with partially or fully positive charges of a group of atoms or a single atom to replace the leaving group. The positively charged atom is known as an electrophile. The electrophile and the leaving group belongs to a whole molecular entity known as the substrate. A general nucleophilic substitution is represented as:

Nucl- + R-LG → R-Nucl + LG-

From the above equation,

Nucl denotes a nucleophile

(-) represents the electron pair

R-LG is the substrate

LG is a leaving group

The electron pair from the nucleophile bonds with the substrate leading to the formation of a new bond. The leaving group moves along with an electron pair. The main product in this reaction is the R-Nucl. The substrate is usually positively charged whereas the nucleophile is negatively charged. It is also possible that the two, nucleophile and electrophile, have electrical neutrality. Hydrolysis of an alkyl halide is a typical example of a nucleophilic substitution. An example of such a reaction is given below:

R-Br + OH− → R-OH + Br−

For organic chemistry, nucleophilic substation reactions are common. These reactions can be categorized broadly as those which occur at saturated aliphatic carbon or aromatic as well as other unsaturated compounds with carbon at the center. The overall process of substitution reactions of this nature can take place through one path or may take two steps. The latter may involve the formation a compound known as carbocation intermediate. The path that is taken in this process and the rate at which the reaction progress is determined by a range of physical and chemical factors. For instance, the relative basicity of the leaving group, the nature of the chemical groups that are linked to C, the temperature of the reactants, the nature of the solvents involved, and the nucleophilicity of the nucleophiles. In some cases, the alkyl halides could be subjected to a competitive substitution process. For example, in the experiment that was conducted, concentrated hydrobromic acid and concentrated hydrochloric acid were used in this case. These halides compete for the scarce alcohol, and the other two are usually supplied in excess. The amount of the conventional products in such a case is determined by the relative reactivity of the halides used. A more reactive acid halide will tend to take more proportion on the product side than the other one. The equation below illustrates the reaction process where the halides exist in a mixed case.





The products formed are alkyl halides with the proportions shown in the equation above. The amounts of each product will be justified later in the discussion section. It is important to note that, the two main products are volatile.

Apparatus and reagents

Water bath

Pre-weighed sample container

100ml Separating funnel

250ml round-bottomed flask

Reflux condenser

2 x 150ml conical bottle

Retort stand and clamp

Filter funnel and filter paper

Concentrated hydrobromic acid

Concentrated hydrochloric acid

Anhydrous calcium chloride

Experimental Procedures

10ml of water was placed into a round-bottomed flask (250ml). 43ml of 0.5mol hydrochloric acid was added to the container. 59ml of 0.5mol hydrobromic acid was then added. A reflux condenser was fitted to cool down the reaction vessel in a water bath. 7.4g of 0.1mole 2-methyl-2-propanol was added to the condenser. Meanwhile, the flask was shaken gently in the course of adding the alcohol. The mixture was then let to settle down for an hour. The mixture was then transferred to a separating funnel. The aqueous layer was removed and collected in a waster beaker. The organic layer was then washed using 2 x 10ml of water. The washing water was removed each time the washing was done, and the organic layer was collected in a conical flask. The content of this container was then dried using anhydrous calcium chloride for 10 minutes. Gravity filtration then removed the drying agent via a fluted filter paper. The filtrate was then collected in a sample container was weight was pre-determined.





Results

Standard

t-butyl chloride



t-butyl bromide



Product

t-butyl chloride and t-butyl bromide



Calculations:

In the calculations that are to be computed in this report, the following parameters will be evaluated:

Response Factor (RF) =

Relative Response Factor (RRF) =

Concentration of A =

Area = heightwidth at the half the height

Moles % =

Chloride height=12632.177mV

Bromide height=12353.239mV

Width at half the height of the chloride = 0.0110min

Width at half the height of the bromide = 0.0118min

Area of the chloride peak = 12353.2390.0110

=135.885mVmin

Area of the bromide peak = 12353.239 0.0118

=148.54mVmin

Response Factor (RF) bromide =

= 297.08mVmin/mol

Response Factor (RF) bromide =

271.77 mVmin/mol

Relative Response Factor (RRF) =

=1.0931

Molar amounts of bromide=

=0.262

Molar amounts of chloride=

=0.737

Discussion

The reactivity of alcohol with halogen varies from one halogen to another based on their position in the periodic table. The general reactivity of halogens in a nucleophilic substitution reaction is as shown below:

I > Br > Cl > F.

The above patterns mean that an iodide efficiently reacts with alcohol while a fluoride trails the list. In our case, the trend was obeyed. This is seen from the products. The concentration of chloride ions in the products was the highest with a percentage of around 74%. This means that in this competitive reaction, the bromide ions reacted faster than the chloride.

Tertiary alcohols react with acid by a mechanism which results in the production of a carbocation in the series of SN1SN1. The alcohol in this case which acts as a substrate is protonated.

For primary alcohols, it is not always a case that when an acid reacts with alcohol, carbonations are formed. Primary alcohols react under acidic conditions to form alkyl halides by an SN2 mechanism.

In this case, the Tertiary alcohols react with acid by a mechanism which results in the production of a carbocation in the series of SN1SN1. The bromide ions reacted at a faster rate than the chloride ions to form an excellent leaving group (water).

Conclusion

The hydrobromic and hydrochloric acids reacted with the tertiary alcohol leading to the formation of a suitable leaving group. A large proportion of alkyl bromide was formed compared to the chloride counterpart since bromide ions readily dissociate.