All the reagents and solvents were obtained from standard suppliers. The 2:1 water:methanol was prepared by the Carleton College stockroom and methanol was degassed with argon with the use of a Schlenk Line, but the rest of the reagents and solvents were used with no further purification. The final step of the synthesis was performed in an inert atmosphere provided by a Schlenk Line. The 1H and 13C spectrums and COSY, DEPT, and HMQC experiments were collected with a Bruker Avance III HD 400 MHz High-Performance Digital NMR Spectrometer.
Cobalt(II) bromide hydrate (2.170 g, 9.17 mmol) was dissolved in acetone (50 ml) which formed a dark blue solution. Dimethylglyoxime (2.209 g, 19 mmol) was added to the solution turning it dark red-brown. The solution was held under a gentle stream of air for 30 minutes and a green precipitate formed. The solution was cooled in an ice bath then vacuum filtered and washed with cold acetone (twice with 15 ml) to yield the green precipitate (1) (2.85 g, 5.97 mmol, 83.9% yield).
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Water (125 ml) was added to the solution then cooled in an ice bath for 10 minutes. The brown crystals (2) were collected by vacuum filtration and dried (2.407 g, 5.37 mmol, 90.3%
The complete experimental procedure is available in the General Chemistry Laboratory Manual for CSU Bakersfield, CHEM 213, pages 20-22, 24-25. Experimental data are recorded on the attached data pages.
The percent yield of products that was calculated for this reaction was about 81.2%, fairly less pure than the previous product but still decently pure. A carbon NMR and H NMR were produced and used to identify the inequivalent carbons and hydrogens of the product. There were 9 constitutionally inequivalent carbons and potentially 4,5, or 6 constitutionally inequivalent hydrogens. On the H NMR there are 5 peaks, but at a closer inspection of the product, it seems there is only 4 constitutionally inequivalent hydrogens because of the symmetry held by the product and of this H’s. However, expansion of the peaks around the aromatic region on the NMR show 3 peaks, which was suppose to be only 2 peaks. In between the peaks is a peak from the solvent, xylene, that was used, which may account to for this discrepancy in the NMR. Furthermore, the product may have not been fully dissolved or was contaminated, leading to distortion (a splitting) of the peaks. The 2 peaks further down the spectrum were distinguished from two H’s, HF and HE, based off of shielding affects. The HF was closer to the O, so it experienced more of an up field shift than HE. On the C NMR, there are 9 constitutionally inequivalent carbons. A CNMR Peak Position for Typical Functional Group table was consulted to assign the carbons to their corresponding peaks. The carbonyl carbon, C1, is the farthest up field, while the carbons on the benzene ring are in the 120-140 ppm region. The sp3 hybridized carbon, C2 and C3, are the lowest on the spectrum. This reaction verifies the statement, ”Measurements have shown that while naphthalene and benzene both are considered especially stable due to their aromaticity, benzene is significantly more stable than naphthalene.” As seen in the reaction, the benzene ring is left untouched and only the naphthalene is involved in the reaction with maleic
This experiment synthesized luminol (5-Amino-2,3-dihydro-1,4-phthalazinedione) and used the product to observe how chemiluminescence would work. The starting material was 5-nitro-2,3-dihydrophthalazine-1,4-dione, which was, after addition of reaction agents, refluxed and vacuum filtered to retrieve luminol. Using two stock solutions, we missed our precipitated luminol with sodium hydroxide, potassium ferricyanide, and hydrogen peroxide, in their respective solutions, in a dark room, to observe the blue light
Triphenylmethyl Bromide. A 400 mL beaker was filled with hot water from the tap. Acetic acid (4 mL) and solid triphenylmethanol (0.199 g, 0.764 mmol) were added to a reaction tube, with 33% hydrobromic acid solution (0.6 mL) being added dropwise via syringe. The compound in the tube then took on a light yellow color. The tube was then placed in the beaker and heated for 5 minutes. After the allotted time, the tube was removed from the hot water bath and allowed to cool to room temperature. In the meantime, an ice bath was made utilizing the 600 mL plastic beaker, which the tube was then placed in for 10 minutes. The compound was then vacuum filtered with the crystals rinsed with water and a small amount of hexane. The crude product was then weighed and recrystallized with hexane to form fine white crystals, which was triphenylmethyl bromide (0.105 g, 0.325 mmol, 42.5%). A Beilstein test was conducted, and the crystals produced a green to greenish-blue flame.
This experiment was divided into two main steps. The first step was the addition of bromine to trans-stilbene. Trans-stilbene was weighted out 2.00g, 0.0111mol and mixed with 40ml of glacial acetic acid in 100ml Erlenmeyer flask on a hot bath. Pyridinium hydrobromide perbromide of 4.00g, 0.0125mol was added carefully into the flask.
In our experiment we utilized the hydrate cobaltous chloride. Hydrates are crystalline compounds in which one or more molecules of water are combined with each unit of a salt. Cobalt (II) chloride hexahydrate is an inorganic compound which is a deep rose color in its hydrated form. As an inducer of
Mixed melting point was used to confirm the identity of the product. The smaller the range, the more pure the substance. When the two substances are mixed; the melting point should be the same melting range as the as the melting range obtained after filtering. If the mixed melting point is lower one taken from the crystals, then the two substances are different.
8. Continue stirring. Record the temperature at which crystals begin to appear in the solution.
[9] 2009, “CRC Handbook of Chemistry and Physics, 90th edition,” American Chemical Society CNC Press, Boca Raton, pp. 631-637
The second reaction had copper (II) nitrate reacting with sodium hydroxide in a precipitation reaction, Cu(NO3)2 (aq) + 2 NaOH (aq) → Cu(OH)2 (s) + 2 NaNO3 (aq). When the 20 milliliters of 6.0 M NaOH was added to the neon blue beaker with the copper (II) nitrate, the extremely light blue color darkened, turning to a darker blue color. Within the solution, an Orbeez-like consistency formed, which was the precipitate, forming copper (II) hydroxide.
Methyl benzoate (0.20 ml), Sulfuric acid (0.45 mL of 18 M), and a spin vane was added to a 5 mL conical vial. An air condenser is attached and clamped to allow proper stirring. A second ice bath was made to hold a 3-ml conical vial of Sulfuric acid (0.15 ml of 18M), and Nitric acid (0.15 ml of 16M). This was added dropwise at two and half minutes per drop to the 5 mL conical vial. This was done slowly so as not to produce TNT. Once completed, the 5 mL vial containing the solution was allowed to warm up to room temperature and sat for 15 minutes undisturbed. Two grams of ice was placed in a 30 mL beaker in which the solution was poured over it. The solution was rinsed with cold water and suction filtered when the ice was melted. The crystals were washed with cold water (2 - 1.0 mL), and methanol (0.3 mL). The product was recrystallized using methanol and allowed to dry. The final beige crystals were weighed, and tested for quality.
In our experiment we observed the physical and chemical properties of two unknowns as well as four knowns that consisted of salicylic acid crystals, magnesium oxide, benzoic acid crystals and calcium carbonate. In terms of polarity we discovered that magnesium oxide,calcium carbonate and “ unknown 2” are polar enough to dissolve in water and not dissolve in hexane. Salicylic acid, benzoic acid and “unknown 1” have similar polarities as both did not dissolve in water and hexane. As for pH, the salicylic and benzoic acid crystals are extremely acidic.
Step 6 was repeated with boiling tube #2 and a warm thermometer (after being placed in the hot water bath) was placed into the solution in boiling tube #1. The boiling tube was held up to the light and the first sign of crystallization was observed As the instant crystallization began, the temperature was observed and
The procedure for this experiment can be found in Inorganic Chemistry Lab Manual prepared by Dr. Virgil Payne.
Inorganic chemistry–II (Structure and mechanism in inorganic and organometallic chemistry, bonding, group theory, basic solid-state chemistry, and spectroscopic techniques.