Melting Point Chromatography

Experiment 55 consists of devising a separation and purification scheme for a three component mixture. The overall objective is to isolate in pure form two of the three compounds. This was done using extraction, solubility, crystallization and vacuum filtration. The experiment was carried out two times, both of which were successful.

In this lab, liquid-liquid extraction was performed to isolate a mixture of benzocaine and benzoic acid. 2.0107 grams of the mixture was first weighed out for the trials. When HCl was added to the mixture for the first acid extraction of benzocaine, an emulsion formed during inversion and venting that prevented a defined separation of the two layers. 8 mL of water was therefore added before continuing the extraction. The addition of NaOH then turned the top aqueous layer basic, indicated by the pH strips that turned blue when tested. A vacuum filtration isolated 0.29 grams of benzocaine and a MelTemp apparatus measured the crystal’s melting point ranges to be 85.1C-87.4C. For the base extraction of benzoic acid, the aqueous layers were retrieved

Me and my lab partner, obtained a mixture of a un known proportion from the instructor and then flow the guide line in our lab manual to separate the mixture by applying the separation method motioned in our lab manual pages 33-40 . In this experiment, the separation methods were decantation,

The objective of this extraction experiment was to achieve a comprehensive understanding, as well as master the practice, of the technique of separating various individual components of a compound.

There are millions of different organic compounds. Most of them are found in mixtures and in order to achieve a pure form they need to be separated, isolated, and purified. However, there are endless numbers of possible mixtures, which make it impossible to have a pre-designed procedure for every mixture. So chemists often have to make their own procedures. The purpose of this experiment was to prepare the student to the real world by them designing their own procedure which will help them understand the techniques of separation and purification better. The goal was to extract two of the components of the

In this experiment, an unknown Grignard reagent was prepared from an aryl halide. The unknown reagent was then reacted with carbon dioxide to form a carboxylic acid. The solid acid was then isolated and recrystallized before the melting point was taken. The precipitate was then dissolved in water and titrated to determine the molecular weight. The melting point and molecular weight were then used to determine the unknown acid obtained from the experiment.

The purpose of this experiment is to prepare a Grignard reagent by reacting with alkyl or aryl halide and to ultimately react the Grignard reagent with carbon dioxide in order to produce carboxylate. The formed carboxylate is then protonated with an acid to produce carboxylic acid that could be used with liquid-liquid extraction to isolate the unknown acid from the other products from side reactions. The final unknown product is identified by measuring the melting point and calculating the molecular weight obtained from titration.

To understand the different separation methods and techniques that depend on the chemical properties of a specific substance. Also to become more comfortable with performing those actions of separation so I have them in the future. For this experiment, I will separate a mixture of four distinct substances: sodium chloride, benzoic acid, silicon dioxide, and iron fillings into pure beings.

In this experiment, the identity of an unknown compound will be deduced from analysis of physical properties, boiling points, IR spectra, chemical tests, and melting points of derivatives. This experiment allows for individual selection of chemical tests, order of steps, and additional analysis, as necessary, based on what is needed to determine identity of unknown.

A ramp rate was first used to obtain the approximate melting point of the unknown before obtaining a more accurate melting point range of the unknown substance. Based on the rapid heating rate of the test, it was determined that the unknown substance was either Trans-cinnamic acid or Benzoin due to the wider melting point range at 132℃. After the second, slower heating rate, it was determined that the unknown might be Benzoin due to the wider melting point range. However, when experimented with the unknown and the Benzoin, the 50/50 mixture melted before the other 2 compounds had begun to change states because it was acting as an impurity instead of melting at the same time. If the unknown and the possibly known substance were the same compound, those two compounds plus the mixture would have melted at the same time. The Trans-cinnamic acid was then compared to the unknown substance, which resulted in two compounds and the mixture melting at the same time, which had a melting point range of 133 to 136.2℃. According to the results of the melting point ranges given, the melting point range of Trans-cinnamic acid should be 132-135℃. The experimented results were 133-136.2℃, which are about a degree higher than what they should be, but the compounds and the 50/50 mixture all melted at the same time, making the unknown substance Trans-cinnamic

After experiment A was completed it was exceptionally clear that there was an obvious difference between the melting points of all mixtures, yet Mixture 1 and 2’s melting point ranges are much narrower than that of Mixture 3’s, as seen on Table 1.A. The results from this experiment help to clearly identify the three unknown mixtures by comparing them to the established melting points of naphthalene and benzoic acid. Mixture 1’s melting point range of 123-125.5 degrees Celsius is in the vicinity of benzoic acid’s melting point of 122 degrees Celsius1; a reason for the discrepancy may be the Mel-Temp was set to rise in temperature too quickly. Mixture 2’s melting point range of 82.3-84.2 degrees Celsius matches closely to naphthalene’s melting point of about 80 degrees Celsius1; similarly this process would have been more accurate had the Mel-Temp been programmed to rise in temperature at a slower rate. And finally the composition of Mixture 3 is most likely a combination of the two, due to the low as well as very wide melting point range, both characteristics of a combination of different compounds2.

The purpose of this experiment was to use solvent extraction techniques in order to separate a mixture consisting of a carboxylic acid (p-toulic acid), a phenol (p-tert-butylphenol), and a neutral compound (acetanilide). Extraction is the process of selectively dissolving one or more of the compounds of a mixture into an appropriate solvent, the solution that contains these dissolved compounds is called an extract (Manion, 2004).

The compounds are separated by collecting aliquots of the column effluent as a function of time.

The objectives of this lab are, as follows; to understand what occurs at the molecular level when a substance melts; to understand the primary purpose of melting point data; to demonstrate the technique for obtaining the melting point of an organic substance; and to explain the effect of impurities on the melting point of a substance. Through the experimentation of three substances, tetracosane, 1-tetradecanol and a mixture of the two, observations can be made in reference to melting point concerning polarity, molecular weight and purity of the substance. When comparing the two substances, it is evident that heavy molecule weight of tetracosane allowed

1. Obtain a sample of the mixture. The mixture you will separate contains three components: NaCl, NH4Cl, and SiO2. Their separation will be accomplished by heating the mixture to sub-lime the NH4Cl, extracting the NaCl with water, and drying the remaining SiO2.