Importance of Stereoisomers in a Biological System

The objective of this lab was to create a ketone through an oxidation reaction using a using a secondary alcohol and oxidizing agent in order to use that ketone in a reduction reaction with a specific reducing agent to determine the affect of that reducing agent on the diastereoselectivity of the product. In the first part of this experiment, 4-tert-butylcyclohexanol was reacted with NaOCl, an oxidizing agent, and acetic acid to form 4-tert-butylcyclohexanone. In the second part of this experiment, 4-tert-butylcyclohexanone was reacted with a reducing agent, either NaBH4 in EtOH or Al(OiPr)3 in iPrOH, to form the product 4-tert-butylcyclohexanol. 1H NMR spectroscopy was used to determine the cis:trans ratio of the OH relative to the tert-butyl group in the product formed from the reduction reaction with each reducing agent. Thin-layer chromatography was used in both the oxidation and reduction steps to ensure that each reaction ran to completion.

The literature values of erythro-2,3-dibromo-3-phenylpropanoic acid and threo-2,3-dibromo-3-phenylpropanoic acid were provided in the laboratory experiment text. Erythro-2,3-dibromo-phenylpropanoic acid held a melting point of 204°C, while threo-2,3-dibromo-3-phenylpropanoic acid held a melting point of 95°C. These two products had vastly different melting point values, which made it clear to observe the product created at the end of the experiment. Once the product was determined due to comparison of melting points, the stereochemistry could be

group. The location of this hydroxyl functional group will impact the molecular structure of the

Grignard reagents are reactive enough to also attach esters; however, two equivalents of the Grignard reagent are usually added because less then two equivalents leave a large quantity of unreactive ester. This reaction forms a tertiary alcohol.

Carbohydrates have two functions which is, provides short term energy and structure in some organisms. They have an atomic makeup of Carbon, Hydrogen, and Oxygen, with a 2:1 ratio of Hydrogen to Oxygen. The monomer is a monosaccharide which contains a single sugar. A couple examples of this would be glucose, fructose, and deoxyribose which is found in DNA. Yet, foods with this monomer in it would be mostly fruits, candy, and soda. Carbohydrates also have a polysaccharide which is a polymer made of many monosaccharides strung together. Some examples of these are starch, glycogen, cellulose, and chitin. A starch is storage from glucose in plants(potatoes, pasta, waffles, and toast). Glycogen is storage from glucose in animals. Cellous is structure in plants (cell wall). Chitin is structure in animals (exoskeleton).

This week in lab a Diels-Alder reaction produced 4-cyclohexene-1, 2-dicarboxylic anhydride by combining 1,3 butadiene and maleic anhydride. They reaction basically combined 4 pi electrons from a diene and 2 pi elections from a double bond to produce an alkene ring. The diene must be in s-cis conformation for the reaction to even happen. All of the p-orbitals, both from the diene and the double bond must line up so it can attack from top or bottom, which creates a chair structure. Because of this, the trans conformation is favored due to the lesser steric interactions.

In the formation of stilbene dibromide, there are three possible products. The first is meso-stilbene dibromide in which the bromines are on opposite sides of the former double bond. The other two products, d-stilbene dibromide and L-stilbene dibromide, are enantiomers with the two bromines on the same side of the former double bond. As enantiomers, d-stilbene dibromide and L-stilbene dibromide are non-superimposable mirror images of each other. Meso-stilbene dibromide makes up 90% of the yield of this reaction, while d-stilbene dibromide and L-stilbene dibromide make up only 10%.

Hydrogens, alkyls, or aryls bonded to carboxyl groups—made up of a carbonyl group and a hydroxyl group—are known as carboxylic acids. Derivatives of carboxylic acids include acid chlorides, esters, anhydrides, amides, and generally nitriles. These derivatives are formed by the replacement of the hydroxyl group with a different electronegative heteroatom substituent, which can be a single atom, such as a chlorine atom, or a group of atoms, such as in the formation of

8a. No, the product wouldn’t be optically active, since it would contain racemic mixture even though each enantiomer is chiral. Diastereomeric recrystallization can be used to resolve the product into optically active constituents, specifically to produce single enantiomer. (Wikipedia).

3. Fatty acids with one double bond in their hydrocarbon chain are called monounsaturated, while those with more than one double bond are called polyunsaturated.

Escitalopram is an enantiomer of a drug called citalopram. Citalopram was discovered in 1977 and is a highly powerful and selective serotonin inhibitor. Citalopram has a chiral center due to its central atom being surrounded by two non matching arrangements of atoms. These surrounding atoms are called enantiomers and are classified as either r-enantiomers or s-enantiomers (Schatzberg & Nemeroff, 2013). It was discovered that many of the positive properties about the drug lie in the s-enantiomer, which is 30 times more potent than the r-enantiomer (Braestrup & Sanchez, 2004). Scientists removed the r-enantiomer, and s-citalopram or escitalopram was created. Some studies have shown that escitalopram may be more effective than citalopram due to the inhibitory effects of histamine of the r-enantiomer (Cipriani, et al., 2012).

As a result, polar compounds have long retention times on polar stationary phases and shorter retention times on non-polar columns using the same temperature. Chiral stationary phases that are based on amino acid derivatives, cyclodextrins and chiral silanes are capable of separating enantiomers because one enantiomer interacts slightly stronger than the other one with the stationary phase, often due to steric effects or other very specific interactions. For instance, a modified -cyclodextrin column is used in the determination of the enantiomeric excess in the chiral epoxidation experiment (Chem

Enantiomers are two same chemical moieties which have a different spatial arrangement. They are described as mirror images of each other, that is they are non-superimposable. They have similar physical properties but differs in some chemical properties. The two different arrangements are classifieds as L- and D-, depending upon the functional group of reference.

Within this experiment we were to analyze four difference analgesic drugs and compare them to different components to see which drug contained what. The components that were used for comparison are Acetylsalicylic acid (ASA), Acetaminophen (Ace), Ibuprofen (Ibu), and Caffeine (Caf). The components all have different levels of polarity. To determine the level of polarity before the experiment even starts can be done by looking at the functional groups. The structures can be found under objectives in the carbon copies with the visual representation of what will be said. After observing each structure and determining the functional groups it can be said that caffeine is the most polar out of all of them. This is because it has two carbonyl groups and four amine groups.

Throughout history chemistry has had a large impact on the field of medicine. Things such as