The Grignard reagent, phenylmagnesium bromide, is highly reactive to water and acetone. When the reagent comes into contact with water or acetone, a side reaction occurs. The Grignard reagent can act as a nucleophile/base and take a proton from the water and as a result, an alkane would form. The Grignard reagent would react with acetone in the same manner and produce an incorrect alcohol. If the glassware used were not correctly dried, incorrect products would be produced thus leading to a less than 100% yield.
b. Discussion of Product Data
The melting point of a product is an index of its purity. The closer the observed melting point is to the literature value, the more pure the product. Additionally, the range of the observed product
No correction had to be made to the melting points because the standard melted in the range labeled on the bottle. The melted point observed is the correct melting point.
What is its melting point? 1,405 K: 1,132 C: 2,070 F. boiling point? 4,404 K: 4,131 C: 7,468 F
Side reactions are reactions that compete with one another that produce unwanted products. One of the competing reactions with the Grignard reaction was the Grignard reagent reacting with oxygen to form peroxide which is very reactive. The second most electronegative element is oxygen. The second competing reaction was the Grignard reagent reacting with carbon dioxide to form a carboxylic acid. The carbon dioxide contains an electrophilic carbon. The products from these two side reactions that are problematic but are not important because there is a very finite amount of oxygen and carbon dioxide that is dissolved in the solvent. If performing the experiment without air completely, then oxygen and carbon dioxide would be eliminated. The third competing reaction is when the Grignard reagent reacts with a halide to form a C-C bond that is not needed.
Melting Point Data Table Compound Aspirin Caffeine Salicylamide Actual MP (ºC) 93 - 98 260 - 262 96 - 102 Expected MP (ºC) 135 236 140 Percent Error (%) ~30% ~12% ~30%
Grignard reagents cannot be synthesized from alcohols because instead of reacting with the halide to form the Grignard reagent, the alcohol is deprotenated. Grignard reagents also cannot be synthesized from molecules with a carbonyl group.
Discussion: As seen in the melting point determination, the average melting point range of the product was 172.2-185.3ºC. The melting points of the possible products are listed as 101ºC for o-methoxybenzoic acid, 110ºC for m- methoxybenzoic acid, and 185ºC for p- methoxybenzoic acid. As the melting point of the sample
Perform the following with three 0.05g samples of unknown and the following solvents: methanol, water and toluene
The Grignard reaction is an important synthetic process by which a new carbon to carbon bond is formed. Magnesium metal is first reacted with an organic halide forming the Grignard reagent. The Grignard reaction is the addition of an organomagnesium halide (Grignard reagent) to a ketone or aldehyde, to form a tertiary or secondary alcohol, respectively. For example, the reaction with formaldehyde leads to a primary alcohol. Grignard Reagents are also used in the following important reactions: The addition of an excess of a Grignard reagent to an ester or lactone gives a tertiary alcohol in which two alkyl groups are the same, and the addition of a
Through the use of the Grignard reaction, a carbon-carbon bond was formed, thereby resulting in the formation of triphenylmethanol from phenyl magnesium bromide and benzophenone. A recrystallization was performed to purify the Grignard product by dissolving the product in methanol. From here, a melting point range of 147.0 °C to 150.8 °C was obtained. The purified product yielded an IR spectrum with major peaks of 3471.82 cm-1, 3060.90 cm-1, 1597.38 cm-1, and 1489.64 cm-1, which helped to testify whether the identity of the product matched the expected triphenylmethanol. The identity of the product being correct was further confirmed by way of both proton and carbon-13 NMR spectra. This is due to the fact
The purpose of this lab was to synthesize triphenylmethanol from benzophenone and bromobenzene by the formation of a Grignard compound with the reagents bromobenzene and magnesium metal. The bromobenzene was first transformed into the Grignard compound and was then reacted with the benzophenone to make the final product. The mixture was then mixed with sulfuric acid and the organic layer was extracted via a separatory funnel. The mixture was then recrystallized from methanol and was allowed to dry and the percent yield, melting point, and the IR was obtained. The mass of the product obtained was 5.45 grams and the percentage yield was determined to be 41.95%. The melting point range obtained from the final product was 89-91°C
There were several possible scenarios that resulted in a loss of product leading to an errant percent yield. There was a small amount of product lost during the first reflux, due to an excess of heat; there was also a minute loss of product when transferring the product from the test tube into the Hirsch funnel. Compared to the melting point of the pure compound as stated in the literature, the experimental melting point was within two degrees, indicating that there was only a minor amount of impurities in the final product. The literature melting point is 262-264 °C. The experimental melting point was found to be, 261.5-262°C.
Solubility – Very soluble (water), Freely soluble (methylene chloride, chloroform, alcohol), Slightly soluble (acetone) and Insoluble (ether).6 Melting point - 120°C or 248°F.5
The melting point for the
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
Brittain, C. G. (2009). Using Melting Point to Determine Purity of Crystalline Solids. Retrieved from http://www.chm.uri.edu/mmcgregor/chm228/use_of_melting_point_apparatus.pdf