CHEMISTRY 30143 SPRING 2018 ORGANIC QUALITATIVE ANALYSIS LABORATORY REPORT FORM UNKNOWN CODE NUMBER: X15 NAME: John Doe Identity of Unknown: 3 NitroXXXX Date: 02/27/2018 Physical State: Solid 1. PHYSICAL CONSTANTS (observed and published) a. List of values measured in the laboratory: b. List of values from the literature: M.P. Range: xxx-zzz o C Lit. Value (ref): yyy o C (text; pg xxx) 2. SOLUBILITY TESTS: soluble (+), insoluble (-) H 2 O 5 % NaOH 5 % NaHCO 3 5 % HCl Conc. H 2 SO 4 Ether - + + N/A N/A N/A Reaction to litmus (water soluble compounds only): N/A Solubility Classification: A 1 3. SODIUM FUSION ANALYSIS X - (halogen) (-)ve CN - (+)ve S 2- (-)ve 4. NEUTRALIZATION EQUIVALENT (NE): Run #1 17.9 ml Run #2 17.8 ml Run #3 17.8 ml Calculations: Neutralization equivalent (NE) = Weight of sample (g) * 1000 Volume of the alkali (ml) * M NE = 0.2 g * 1000 17.8 ml * 0.0683 M NE = 164.51 (observed / calculated) Neutralization equivalent (NE) = Molecular weight of the compound NE = 167.12 (MDL Beilstein)
5. INFRARED SPECTRUM: N/A 6. NUCLEAR MAGNETIC RESONANCE SPECTRUM: N/A 7. MASS SPECTRUM: N/A 8. CLASSIFICATION AND SUB-CLASSIFICATION TESTS No. Name of Test Specific Observations and conclusion (+ve or ve) (1) (2) (3) (4) (5) (6) Sodium Bicarbonate Test Test for carboxylic acids (Experiment 31) Bromine Water Test Test for phenols or anilines (Experiment 46) Sodium Hydroxide Test Test for Aromatic Nitro groups (Experiment 44) Potassium Permanganate Test Test for alkenes or alkynes (Experiment 38) Chromic Anhydride Test Test for 1 0 or 2 0 alcohols (Experiment 08) 2,4-DNP Test Test for aldehydes or ketones (Experiment 12) Gas evolved spontaneously. (+)ve test presence of a carboxylic acid Bromine color did not discharge; solution remained brown color. (-)ve test absence of a phenol or aniline Initially no observation; after 30 minutes, solution turned pale yellow. (+)ve test presence of nitro group (not a very strong conclusion) Solution remained purple color; no precipitate was formed. (-)ve test absence of alkene or alkyne Solution remained orange. (-)ve test absence of 1 0 or 2 0 alcohol No observation; precipitate was not formed. (-)ve test absence of aldehyde or ketone Specific functional groups consistent with parts 2 and 3: COOH & NO 2 (Classification tests were carried out after listing a table of possible compounds within a particular melting point range. Therefore tests for 3 0 alcohols, amines, amides, and other functional groups were not required to be carried out.)
9. TABLE OF POSSIBLE COMPOUNDS Compound Name & Structure Propanedioic acid (malonic acid) 1-Naphthaleneethanoic acid 2-Acetylbenzoic acid (aspirin) Melting point (MP) ( o C) NE 135d 52.03 135 186.21 135 164.16 Specific Reason for Ruling Out equivalent (NE) is 164.51; but the lower. equivalent (NE) is 164.51; but the The unknown did not contain a keto-group (2,4-DNP test); but this molecule contains a ketogroup. 1,5,5-Trimethylcyclopentene-2-carboxylic acid 135 154.21 The unknown was saturated; but this is unsaturated. 2,4-Hexadienoic acid (sorbic acid) 135 112.13 The unknown was saturated; but this is unsaturated.
3-Phenylpropynoic acid (phenylpropiolic acid) (+/-)-cis-camphenic acid 137 146.15 137 154.22 The unknown was saturated; but this is unsaturated. The unknown was saturated; but this is unsaturated. E-2-chloro-3-phenyl-2-propenoic acid 2-Methylpropanedioic acid 138 182.61 138d 59.05 NE of this molecule is 2-Pyridinecarboxylic acid (2-picolinic acid) 138 123.11 (did not ruled out)
5-Chloro-2-nitrobenzoic acid 139 201.57 (R,S)-2,3-Dihydroxybutanedioic acid 3-Nitrobenzoic acid 140 75.04 141 167.12 The unknown did not contain a OH; but this does contain. This molecule fits all the classification descriptions as well as the observed neutralization equivalent (NE). (can not be ruled out) 2-Chloro-4-nitrobenzoic acid 142 201.57 4-Chloro-2-nitrobenzoic acid 142 201.57
Z-3-Chloro-3-phenyl-2-propenoic acid 2-Chlorobenzoic acid 142 182.61 142 156.57 NE of this molecule is Octanedioic acid (Suberic acid) 144 87.10 lower. 2-Aminobenzoic acid (anthranilic acid) 144 137.14 (did not ruled out) 2,4,5-Trimethoxybenzoic acid (asaronic acid) 144 212.20
2-Chlorophenoxyethanoic acid 2-Nitrobenzoic acid 146 186.59 146 167.12 This molecule fits all the classification descriptions as well as the observed neutralization equivalent (NE). (can not be ruled out) 2-Carboxyphenyl-2-oxoethanoic acid 146 97.07 lower. Diphenylethanoic acid (diphenylacetic acid) Oxodiethanoic acid (diglycolic acid) 148 212.25 148 67.05 lower. MP range used to construct Table 9 (Carboxylic acids): 135 148 o C (Observed melting point of the purified unknown compound was 140-141 o C. However if some specks of impurities were present the melting point could be slightly lowered. Therefore in choosing the range, 5 o C was taken below and 7 o C was taken above the observed melting point. No compounds were omitted.)
10. REFINED LIST Compound Name MP ( o C) NE Derivatives and their Melting Points ( o C) (Amide) (4-Toluidide) 2-XXX 138 123.11 107 104 3-XXX 141 167.12 143 162 2-YYY 144 137.14 109 151 2-YYY 146 167.12 176 203 11. PREPARATION OF DERIVATIVE Name of Derivative Observed MP range Literature MP and Reference Amide 139 140 o C 143 o C (text; pg 606) 12. CONCLUSIONS The first unknown (A4), was a white solid. The first step was to carry out the solubility tests. The compound was insoluble in cold water. It dissolved completely in hot/boiling water (The water was cooled and the compound was recovered. This showed that the compound had not decomposed or reacted). Considering the compound to be insoluble in water, it was treated with 5% NaOH, in which it dissolved. Next it was treated with 5% NaHCO 3 and it dissolved. This classified the compound in the A 1 solubility class. It was a carboxylic acid with more than six carbons, a phenol with electron withdrawing groups or a beta-diketone. Since the compound was soluble in hot/boiling water, it was next treated with ether, in which it dissolved completely. Next the partially dissolved compound was tested with litmus paper. It turned blue litmus to red color, showing that it was an acid. This also classified the compound to the solubility class S A, which stated that the compound would be a monofunctional carboxylic acid with five or fewer carbons or an arylsulfonic acid. This was done in order to include all the possibilities. Since both solubility classes spoke of carboxylic acid either with more than six carbons or less than six carbons, it could be inferred that the unknown was a boarder-line situation. However this inference was not taken for granted; each possibility was tested.
Secondly, the melting point of the crude compound was measured to be 136-138 o C. Once purified and recrystallized, a sharp melting point was observed; which was 140-141 o C (In recrystallizing the compound water was used as the solvent for the unknown was partially soluble in water). Thirdly, classification tests were carried out. The Sodium Bicarbonate test gave positive results. It was inferred that a carboxylic group was present. This was enough evidence to have formed that first list of possible compounds. However a Bromine Water test was carried out to look for the possibility of a phenol. This gave negative results, making it possible to infer that a phenol was absent. Next, a possible list of compounds was put together solely based on the melting point range and the presence of a carboxylic group. Usually in the presence of impurities the melting point of compounds decreases slightly. Although the unknown compound was purified there could have been a chance for some traces of impurities to lower the observed melting point. Thus when listing the compounds 5 o C were taken below and 7 o C were taken above, giving a range of 13 degrees (135-148 o C). There were 25 possible compounds in the list. There structures were drawn-out and studied. Different functional groups were noted down. Among the compounds the following functional groups were present; -NO 2, -Cl, carbonyl, alkene, alkyne, -OH, NH 2, and ethers in addition to the carboxylic group. Next, classification tests were carried out again to verify the possible functional groups that were present in the compound list. Sodium Hydroxide test was carried out to look for the presence of a -NO 2 group. The colorization of the solution occurred after a prolonged period of time. This was not a very conclusive test for the results should have been immediate. However the presence of the COOH group which is also a EWG on the benzene would have deactivated the system further. This explains the long time it took for the positive result and could be concluded as a positive test. However, this result was not used to eliminate any possibility. The other classification test that were carried out included; the Potassium Permanganate test for unsaturations, the Chromic Anhydride test for the presence of 1 0 or 2 0 alcohols and the 2,4-DNP test for the presence of carbonyl groups. All three of these classification tests gave negative results and the absence of alkenes, alkynes, 1 0 or 2 0 alcohols, ketones or aldehydes was concluded. Other classifications such as the test for amides, amines, amino acids, 3 0 alcohols and all the rest were not carried out, because they were not included in the list of the possible compounds in the selected melting point range. The next analysis/classification was the Na fusion analysis. Here the compound was tested for the presence of Cl -, CN -, and S 2-. The test for Nitrogen was positive, while it was negative for both Sulfur and Halogens. This allowed shortening the list of the large amount of possible compounds. After the results of the Na fusion and all the other classification tests, sufficient data was available to refine the table and reduce the number of compounds to four. These compounds are included in the refined list (No.10). Next a titration was carried out to compute the neutralization equivalent (NE). After three careful runs, the NE was calculated to be 164.51. The NE was able to eliminate two more of the compounds on the refined
listed. However the NE was unable to distinguish between 3-XXX and 2-XXX, for they had the same neutralization equivalent. Thus it was required to form derivatives to distinguish between the few possibilities left (The NE value is unique to given compounds, but it was not use to discard the other two possibilities and derivatives were formed in order to identify the proper compound). After studying the differences between the melting points of the derivatives of the four possible compounds, the amide and the 4-Toluidide derivatives were prepared. The purified amide had a melting point of 139 140 o C which clearly separated the 3-XXX acid from the rest of the possible compound and especially from the 2-XXX, for the 2-YYY acid and 2-ZZZ acid could have been ruled out based on the neutralization equivalent as well. To reconfirm the identity a second derivative was formed. However it was not as successful as the amide, for its pure yield was significantly small and the melting point was significantly lower. Although the melting point was about 10 units lower than the expected, this too supports the fact the compound was 3- XXX over the 2-XXX, for there is a clear difference between the melting points of the 4-Toluidide derivatives of the two compounds. As in the case of all research, the unknown molecule did not identify itself directly. With the help of a systematic elimination process, it was possible to identify 3-XXX. All the tests and analyses were in favor of 3- XXX. The melting point of the purified compound 140-141 o C, is overlapping that of 3-XXX. The neutralization equivalent 164.51 is close to that of 3-XXX, which is 167.21. The different of 3 units could be due to the presence of slight impurities in the compound or a slight variation in the standardized solution of NaOH. The presence of the only functional groups was WWW & VVV and this is true in the case of 3-XXX. The solubility class was A 1. This is true for 3-XXX which has X carbon atoms. The observed melting point of the amide derivative 139 140 o C, is close to the literature value (143 o C). The depression could be due to the slight contamination of compound. The identity of compound X15 is 3-XXX.