Saturday, March 18, 2006
Thursday, March 16, 2006
The Chemistry Behind Lightsticks
Almost everyone has seen a lightstick. A lightstick is a plastic tube with a glass vile inside it. When the tube is bent, the vial breaks allowing the chemicals to mix and react. The colorfully glowing sticks utilize a chemical process called chemiluminescence where energy is released in the form of light. The most common lightsticks use chemiluminescence with colored tubes to provide the desired color.
This process is not caused by heat and may not produce heat, but the speed of reaction is still dependence on environmental heat. The colder the environment, the slower the reaction and will glow longer.
Lightsticks have three parts. There are two chemicals that react to release energy which is converted to light. Usually, commercial lightsticks utilize the reaction between hydrogen peroxide and acetonitrile. When the glass vile is broken and the two chemicals are mixed, it will release enough energy to excite the electrons in the oxygen to cause the electrons to jump to a higher energy level and then fall back releasing light.
Specifically, the hydrogen peroxide oxidizes the acetonitril eventually forming excited oxygen. This decomposes and releases the energy as light as can be seen stepwise above.
More on chemiluminescence can be found here on “A Chemiluminescence Reaction between Hydrogen Peroxide and Acetonitrile and Its Applications.”
Tuesday, March 14, 2006
Exam Quiet Time Reservations
Tuesday March 21st Room C-104 3:00-9:00 pm
Room B-103 has been reserved on Monday March 20th and Wednesday March 22nd from
Friday, March 10, 2006
This maze is all about IR and NMR and is a good way to review the material for the test and exam.
Monday, March 06, 2006
iPod won today
I think all of the NMR concepts we covered in this class are in there so you may want to try this one to practice for the test.
Lets do another race on Friday, although I can't promise there will be another ipod available.
Tuesday, February 28, 2006
Feb 27 race
The ipod video will be up for grabs at the next race - lets shoot for Monday March 6th for the next race.
I would like to include some NMR in the next race so if you were thinking of doing your extra credit on UT doors, this would be a good time to work on it.
Also note that I can help you with ANY class topic at the workshops.
Tuesday, February 21, 2006
We'll also have another Unreal Tournament race on that day, covering the basics from CHEM241 and possibly anything in CHEM 242 up to and including NMR. The video ipod is still available as a prize.
Of course, I am also there to help with the class material, as usual. Generally students find NMR to be a little harder than the rest of the material so don't procrastinate coming to the workshops for help with that.
Friday, February 17, 2006
Feb 17 2006 race
He won a book - the video ipod is still up for grabs.
Attend the next race Friday at 10:00 in Matheson 109 for a chance to win it.
Thursday, February 16, 2006
Fischer Esterification: 2-ethylhexyl benzoate
Fischer esterification can be a time-consuming process, requiring days for a reaction to reach equilibrium. In this article, researchers developed a way to hasten this process by using a specially designed microwave to heat the reaction quickly and evenly and at an increased pressure. In order to test the efficiency of the device, they synthesized 2-ethylhexyl benzoate from benzoic acid and 2-ethylhexanol as shown below.
Sulfuric acid as well as para-toluene sulfonic acid (PTSA) were used to catalyze the reaction. In order to shift the reaction towards the products, a large excess of 2-ethylhexanol was used and the water produced was constantly removed. One of the disadvantages of Fischer esterification is that dehydration can also occur, resulting in unwanted ether and alkene products. Because of this, the temperature and catalyst concentration must be carefully monitored. The researchers were able to show that microwave heating causes no ill effects on the reaction and reduces the time required to a matter of minutes while still producing a high level of the desired product.
Monday, February 13, 2006
Feb 13 2006 Race
Nick was the winner in 6 minutes. He drew the consolation prize (cat keychain). The ipod video will be up for grabs at the next race - we'll try for Friday.
Sunday, February 12, 2006
Hock Process in the Manufacture of Phenol
Phenol is more important than most people realize. It can be found in many consumer products including aspirin, head lights, gas tanks, billiard balls, nylon, wintergreen gums, Pepto Bismol, deodorant and more. A side product in the manufacture of phenol is acetone which is also used in the private sector in plastics, solvents, and more.
The high-yield manufacture of phenol uses the concepts of peroxidation and cleavage. Cumene (i-propyl benzene) is oxidized by exposure to air to temporarily produce cumene hydroperoxide. The cumene hydroperoxide is simply cleaved at the top of the benzene ring using an acidic catalyst to produce the two usable products of phenol and acetone. The catalyst is extracted and the phenol/acetone mixture is fractionated and purified. Under optimal conditions, 1.31 tons of i-propyl benzene (cumene) will produce 1 ton of phenol and 0.615 tons of acetone. The end-product phenol purity is at 99.99 wt % with total impurities of only 60 ppm. This process is termed the Hock process after being discovered by Hock and Lang in 1944. This process was ideal since both products were useful and relatively pure. Modern demand, however, for phenol is increasing at a higher rate than acetone. This means that the future may classify acetone as a partial waste product. More information on the Hock Process of manufacturing Phenol can be found here which expands on the Benzene-Free Synthesis of Phenol or here which discusses Selective decomposition of cumene hydroperoxide into phenol and acetone by a novel cesium substituted heteropolyacid on clay.
Wednesday, February 08, 2006
Race on Monday - try to win an ipod
I may include contributions from students in this class so this might be a good time to work on your extra credit due by Feb 17th.
The first student to make to the catroom has an equal chance of winning one of the following:
- 30Gig video ipod
- molecular model kit
- consolation mystery prize
Thursday, January 26, 2006
Tuesday, January 24, 2006
Powerpoint and Problem set downloading
You may now download the Powerpoints and the problem set pdf off of the class wiki (Items 4 and 12)
Monday, January 23, 2006
Class Vodcast available
The quality is not as good as the Flash screencasts but it should be usable for the most part. Let me know how you find it.
The first 2 weeks are up now - more to follow.
second week update
The first test is coming up in 2.5 weeks.
Remember that the Friday workshops are in Matheson 109.
Sunday, January 15, 2006
First week update
2) You should all have completed lecture 3 by this point (alkynes). If you are having any technical problems it is imperative that you deal with this at the next workshop on Wednesday.
3) We ran into a few glitches this week with accessing the Real Player lecture recordings but I posted a workaround on the wiki so that you would still have access through the guest account. Right now the Real Player lecture archive in WebCT is working fine. The PDFs associated with some of the lectures have been moved to Item 11 on the wiki. Not all the lectures are there yet but the ones for the first week are and the rest will be there shortly.
Monday, January 09, 2006
Welcome Winter 2006 class
Saturday, August 20, 2005
Last Blog Assignment Deadline Over
I have been impressed with many of the posts. Most of you found relevant articles and extracted the information you needed. Several of the posts were about very practical things like environmentally friendly synthetic approaches, alternative fuels, breathalizer chemistry and the use of enzymes and biological agents to clean up pollutants.
One of the reasons I started this blog assignment is to help you understand how the reactions you are learning are used by chemists in the real world of research and industry. A side benefit is that I have learned some chemistry on each and every post. As a chemist you will never stop learning. What I am hoping is that in this class you have learned the skills to find the information you need to use chemistry productively in your career.
Another bonus is that other people from around the world are benefiting from your posts. Click on the SiteMeter button at the bottom of the blog then click on referrals to see how people are finding your posts.
I will be cleaning up the blog at the end of the term, removing unreadable or substantially incorrect posts. If you wish to keep your posts make sure to copy them before then. In Blogger you can copy a post from one blog to another easily. Just make sure you copy and paste in the "Edit HTML" view, not "Compose". Note that you can also convert the posts into Word. You may wish to do this also if you want to build an e-portfolio.
Friday, August 19, 2005
Bimolecular Dehydration of 1-Pentanol to Di-n Pentyl Ether (DNPE)
However, the dehydration reaction results in quite a lot of byproducts, including other ethers. As such, a selective catalyst is required to favor production of DNPE by reducing the amount of alkenes. Increased selectivity can be accomplished via gel-type acidic resins at a reaction temperature of 150°C. The article I looked at analyzed the selectivity and reaction rate of the dehydration of 1-pentanol to DNPE using a gel-type resin at various temperatures and alcohol flow rates. Article Link.
Recent advances in solventless organic reactions: towards benign synthesis with remarkable versatility
Recently there has been a paradigm shift away from using solvents in organic synthesis as solventless reactions can lead to improved outcomes, and more benign synthetic procedures, in for example an aldol condensation reaction as shown above. Sustainability is increasingly an important issue in broader context when you are talking about health, energy, and the sciences. Removing organic solvents in chemical synthesis is important in the drive towards benign chemical technologies. Organic solvents are high on the list of toxic compounds due to the problems in containing volatile compounds and the sheer large volume of them used in industry.
Some advantages of utilizing solventless reactions are that the compounds are often sufficiently pure to avoid extensive purification using chromatography, the reactions can be rapid, often reaching substantial completion in several minutes compared to hours in organic solvents, and the energy usage can be much lower.
For the full text click here.
Monday, August 15, 2005
Free-Radical Polymerization: Alkoxyamine Initiators
Polymers have important uses in both research and industry. Alkoxyamines are used in ATRP (atom transfer radical polymerization)-based polymerizations and can serve as efficient regulators in the preparation of polymers. In the past, the alkoxyamines were produced by the creation of radicals that are carbon-centered and were then trapped by nitroxide. This method, however, gave low yields and undesired byproducts. The reaction shown here takes place at low temperatures and in the presence of a nitroxide, utilizing an ATRP-based initiator that is treated with copper bromide. The ATRP is involved in the living radical polymerization system. Me6-tren ligand forms a catalyst complex for the reaction of the initiator with nitroxide. Equilibrium between the transfer to and from radicals and dormant species in the reaction is controlled by the Me6-tren ligand forming a complex with the Cu(II), which the free radicals can then interact with. The catalyst name Me6-tren stands for the chemical tris(2-(dimethylamino)ethyl)-amine. This is a more effective procedure for preparation that results in high yields. Discoveries such as this are important in areas such as nanotechnology.
Here is the CiteULike article.
This source discusses the use of alkoxyamines in free-radical polymerization.
Sunday, August 14, 2005
Diels-Alder reaction of Quinol Lactone
This is a Diels-Alder reaction, which does not follow the regiospecificity rules. What makes this reaction unusual is that normally quinol-lactone does not react with dienes. Also if we follow the regiospecificity rules we would logically expect to get the structure in Figure 2. However by using stannic chloride (SnCl4) in methylene chloride, the product shown was obtained. It was determined through NMR spectroscopy that this particular product was present, and not its isomer in Figure 2. TBSO stands for the tert-butyldimethylsilyl group.
The reaction is described in this article.
I found an article which looks more closely at the process of migration and elimination of TBS when the final product is synthesized, which produces TBSOTf. It states that stannic chloride causes the migration of the tosyl group (1st paragraph of "Results and Discussion" section). I believe this plays a role in the final "inversion" of the product in the posted reaction. Also this Diels-Alder reaction is performed in Lewis acid which gives the regioselectivity opposite to what we would expect in an uncatalyzed reaction.
The product in Figure 2 should be expected, because if we examine the ortho-para rules for regioselectivity through the formation of radicals without a catalysit (Lewis acid), we can see that the major product should resemble the one in Figure 2. There is an example on this page under the "Regioselectivity" section, which has the major product boxed in.
Thursday, August 11, 2005
Zinc reduction of alkynes
A traditional method for the reduction of alkynes to trans-alkenes is to dissolve metal reduction using sodium or lithium in ammonia. However, we can also use Zinc as a metal to reduce alkynes.
In this specific case, by changing the proton source in the reaction, the dissolving Zinc metal reduction of ethyl phenylpropiolate to the corresponding cinnamate ester can be stereochemically controlled.
The product of the reaction will be a mixture of cis and trans ester. By this reaction, we can see the efficiency of Zinc in the reduction of alkynes.
For more reference, please click on:
Monday, August 08, 2005
Benzoylation of a Polyol
Amino polyols are an important part of synthetically created amino acids. They are highly antibacterial and immunosuppressive and so are used in various antibiotics and antifungal products. This reaction shows one of the step necessary in creating the amino polyol.
Benzoyl chloride is added to the polyol to form a tribenzoate compound. In this reaction, the polyol has several R-O-H groups that act as weak nucleophiles. When the benzoyl-Cl bond breaks upon addition to the pyridine solvent, the benzoyl group acts as an electrophile. With the help of the DMAP (dimethylaminopyridine) catalyst in the reaction, the R-O-H group is deprotonated and the benzoyl group is added to the remaining R-O form the final tribenzoylated product. As seen above, the reaction has a yield of about 90%. The OTBS (t-buytldimethylsiloxy) groups do not participate in this reaction.
There is one hydroxyl group left on the molecule produced. All of the hydroxyl groups would be replaced by benzoyl groups if the reaction was not stopped after three groups had been added. To stop the reaction at this point, three equivalents of benzoyl chloride were used for every polyol.
For the full text of the article describing this process, see this report.
Friday, August 05, 2005
Asymmetric synthesis of monohydroxy tetradecanoic acids
Methyl 3-, 6- and 13-oxo tetradecanoates went through reduction with NaBH4 in the presence of 1,2:5,6-di-O-isopropylidene-Dglucofuranose (DIPGH) and menthol together with isovaleric and pivalic acids in THF solution. This work signifies the importance of positional
effect. The position of lower steric hinderance and higher enantiomeric excess and asymmetric reduction yield were noted down, namely the prochiral 13-keto isomer structures.
With this asymmetric reduction at normal atmospheric pressure together with inexpensive auxiliaries make it competitive with other reduction methods and is needed to assess the need in the market. Here's a link for this article
Chemistry of a Breathalyzer
Using Beer's law, the spectrophotometer can relate concentration to absorbance levels of the chromium ion. The amount of alcohol present is proportional to the stoichiometric coefficients. An actual breathalyzer only needs to detect 25 micrograms of ethanol to give a reading 0.10 Blood Alcohol Level.
Thursday, August 04, 2005
Synthesis of S-Adenosylmethionine Synthetase
The sulfonium salt S-adenosylmethionine is one of the most widely used biological methylating agents. It is formed by the ATP activation of methionine. One of the most benifical uses of this salt is to convert norepinephrine to epinephrine (adrenaline). Many times this conversion happens in flight or fight organs, which leads to vasodilatation. This vasodilatation in turn leads to an increased blood flow to the organ/tissue or interest.
The reaction shown is the formation of S-Adenosylmethionine. This process occurs in two steps as can be seen. The first step cleaves the whole phosphate of the ATP. However before the sulfur of methionine attacks the C5` atom of ATP (via SN2) there is further hydrolysis of the cleaved tri-phosphate into two inorganic phosphates (di and mono).
Here's a link
Synthesis of Phosphate Monoesters
The paper describes that it was experimentally determined that the best solvent, tertiary amine, and catalyst (or nucleophilic base) for the reaction are DMF-nitroethane, tributylamine, and N-butylimidazole, respectively, each giving the highest yield. This is a summary of the main reaction discussed in the paper.
* The article states that water was constantly removed by azeotropic reflux, so that the reverse reaction was prevented.
I have also included an interesting extensive study on phosphate monoesters.
Wednesday, August 03, 2005
Reduction of Aldehyde to an Alcohol -- Synthesis of D,L-1,2,4-butanetriol
For the full text of this article, click on the following link (and then the second listed link in citeulike):
Tuesday, August 02, 2005
Anaerobic Toluene Oxidation in the Metabolism of the Fe(III)-Reducing Microorganism GS-15
This is a potential pathway for the oxidation of toluene in Fe(III)-reducing microorganisms, which play important roles in sediments naturally composed of hydrocarbons. The oxidation of toluene, an aromatic hydrocarbon, in these microorganisms is coupled to Fe(III) reduction. GS-15 is the first microorganism discovered to link aromatic compound oxidation to the reduction of Fe(III). The oxidation of p-cresol and phenol in these organisms is also coupled to Fe(III) reduction. Under strict anaerobic conditions in these organisms, GS-15 can completely oxidize toluene to carbon dioxide by utilizing Fe(III) as the only electron acceptor in the reaction.
This mechanism can be used to clean up toxic oil spills or other toluene contaminations by introducing the microorganisms to the site.
Here is the link to the CiteULike article discussing these anaerobic metabolic processes.
Play for points
As an alternative to this final blog assignment you may volunteer to evaluate the Unreal Tournament maps we have available on the class material. The deadline for this is also August 19th. Don't wait too long to sign up for this because it will require scheduling. If you don't have UT I'll give you access to a computer.
Contact me if you are interested.
Monday, August 01, 2005
Cesium fluoride-Celite: a solid base for efficient syntheses of aromatic esters and ethers
In the syntheses of aromatic esters and ethers, CsF-Celite has been found to be a very efficient, convenient and practical reagent. In fact, it is used for the coupling reactions of a number of aromatic and heteroaromatic phenols with alkyl, acyl or benzoyl halides.
Many other organic reactions have recently been catalyzed by CsF-Celite, such as the reactions to synthesize carboxylic esters, γ-lactones, N-alkylation of anilines, or carboxamides.
For more reference, please click on http://www.citeulike.org/user/hongan1985/article/270811
Wednesday, July 27, 2005
Production of ketone from an alcohol: an unwanted side product
The above reaction shows an epimeric steroid alcohol being converted by a catalyst of ruthenium and aluminum oxide to a racemic mixture of 17-estradiol 3-methyl ether and a ketone. The racemic mixture is formed by converting the beta version of the ether, where the hydroxyl group is on the top of the ring, to the alpha version of the ether, where the hydroxyl group is underneath the ring. The reaction is stopped when the amount of alpha ether is roughly equivalent to the amount of beta ether. In the notation used, the wavy line between the hydroxyl group and the ether shows that the hydroxyl group can be in either the front or the back of the molecule.
However, a ketone can be produced instead of the alpha ether when the alcohol is oxidized. Because the purpose of the reaction is to racemize the ether, this ketone is an unwanted side product. To prevent oxidation, toluene at 100 C is used as a solvent. The chemical properties of toluene slow the formation of the ketone so that at temperatures around 100 C, the yield of the racemic mixture is about 54%. Any ketone that does form can be separated from the ether by flash chromatography. This reaction is a good way to racemize the ether efficiently and inexpensively; it was traditionally synthesized at a much higher cost.
For the full text of the article describing this process, see this report.
Sunday, July 24, 2005
Even if something seems simple to you, it may not be for everyone. A good way to know if a screencast it useful is to notice recurring errors made by student in their blog assignment.
-how to find a reaction in the literature
-how to use CiteULike
-how to post to Blogger
-how to resize pictures
-how to link to a reference without pasting the entire url in the post text
-how to tell if a reference is suitable
Saturday, July 23, 2005
Second deadline over
1) Most of you are now using CiteULike properly so there are now plenty of examples other students can look at to see how it should be done.
2) It would be nice if you could tag all your articles with "orgo" so that all the articles of the class could be tracked with an RSS feed.
3) Many of you are giving a lot more than what I am asking for an running into some trouble in the process. All I want is one single reaction with nice readable molecules drawn from ChemSketch (or by hand as a last resort) with an arrow and reagent on the arrow. It will be easiest for you to pick a reaction that we covered in class because you won't have to explain it in as much detail.
4) If you want to give me more information that is fine but make sure that you support your statements with a link to a document with primary data (like experimental results) or to a document where the information trail continues on to primary data. For example, "progesterone reduces the risk of cancer" should be clickable to an article where the actual study has this as a conclusion OR to an article that has a similar statement with a link to primary data. References lumped at the end of your post are not good enough. Articles that you link to with general references at the bottom are also not usable. Unfortunately this means that a lot of government public health sites or company websites are not suitable for references. Your opinions and your speculations don't have to be supported by a reference. Try to post well before the next deadline so I can help you get this right.
Friday, July 22, 2005
Synthesis of Lupinine Esters from Betulonic Acid Chloride
The reaction shown above outlines the synthesis of the lupinine ester. These esters have been studied for their biological properties. Found mainly in plants there is heavy research being done on them for their antiviral, antitumor and hepatoprotective activity. In some cases lupinine esters can exhibit local anesthetic properties.
The reaction shows how you would synthesize a lupinine ester from betulonic acid chloride with lupinine. Side conditions for this reaction include the presence of triethylamine and must be performed in dry CCl4.
Production of Hydrogen by means of hydrogenation of ethanol
This journal describes a special method of low-temperature dehydrogenation of ethanol over special Raney catalyst with Cu added to it. The first step produces one mole each of hydrogen gas and acetaldehyde (per mole of ethanol). This is followed by the decarbonylation of acetaldehyde to form methanol and CO. The whole reaction undergoes a water-gas shift to net one mole each of Methane and Carbon dioxide and two moles of Hydrogen.
Compared to high temperature reformation methods, which produces 6 moles of hydrogen per mole of ethanol, this reaction doesn't seem as fuel efficient, though the authors were confident, that with an internal combustion engine on-board that uses the methane produced as fuel, the total output energy would be equal.
Thursday, July 21, 2005
Catalytic Hydrogenation of an Acid
This reaction is an example of the catalytic hydrogenation of an acid in an ionic liquid similar to the reagents sodium metal/liquid ammonia discussed in lecture. This particular reaction has sorbic acid and hydrogen gas reacting with a ruthenium catalyst and a biphasic 1-butyl-3-methyl imidazolium hexafluorophosphate (bmimPF6)/methyl tert-butyl ether (MTBE) system to create cis-hex-3-enoic acid. The above reaction occurs with ~85% selectivity. The author of this paper was examining enantioselective hydrogenation in ionic liquids because this mechanism could provide a means for facile recycling of metal complexes of expensive chiral ligands. The author also studies some hydrogenation reactions that lead to the precursor of the antiinflammatory drug ibuprofen, the active ingredient in Advil.
For the full text click here.
Preparation of Progesterone from Cholesterol
This is what I understand happens, following the process of production of progesterone, described on page 894, second column.
In the first two steps cholesterol is brominated in benzene, and oxidized in a solvent with acid permanganate(aq). In the last step the product is again debrominated using zinc dust.
The strong oxidizing agent potassium permanganate is used, as well as sulfuric acid. The article below describes the process of production of progesterone from cholesterol.
Progesterone has numerous physiological effects. Although primarily associated with the reproductive system, progesterone has multiple effects outside of it. This steroid hormone can act as an antiinflamatory agent, reducing the immune response; it can also assist in thyroid hormone action and bone building. Progesterone appears to prevent endometrial cancer (cancer involving the uterine lining) as well as breast cancer (1).
Wednesday, July 20, 2005
Williamson Synthesis of Ethers
The above reaction is an example of a Williamson synthesis of an ether. It is one the earlier steps in the reaction mechanism resulting in the octaethylene glycol derivative of 1,1,1,3,5,5,5-heptamethyltrisiloxane. Such an initial Williamson synthesis reaction had to be carried out so that later steps in the reaction—that is, ones involving material types not readily accessible—could successfully yield the derivative product. The resultant glycol derivative is an example of a defined surfactant. This particular journal article focused on the correlation between surfactant constituents and the effect on properties such as spreading performance.
The Williamson synthesis involves an SN2 reaction in which a halogen, sulfonyl, or sulfate group is replaced by an alkoxide ion, which can itself be prepared by a reaction of the alcohol with an active metal such as sodium or its hydride (i.e. NaH). The resultant alkoxide salt then reacts with the alkyl halide (must be primary) to produce an ether via the SN2 mechanism.
Other examples of Williamson synthesis of ethers can be found in this same reaction mechanism used to produce the surfactant. Article Link.
Tuesday, July 19, 2005
The reaction seen above is an example of a substitution nucleophilic 1 reaction. The mild reaction conditions and high yields makes the Lucas reaction a convient way to be utilized in the industrial-scale preparation of alkyl chlorides from aliphatic alcohols. However, the wide use of the Lucas reagent in industrial settings is limited due to the cost of ZnCl2. This reaction proceeds rapidly and is needed for the fast demand and industrial use of menthyl chloride.
Monday, July 18, 2005
Methanol Synthesis and Dehydration Combined in a Single-Stage DME Synthesis Process
Dimethyl ether (DME) is a multipurpose clean fuel and chemical feedstock that can be produced from a wide variety of of sources and has a number of important applications. About 10,000 tons of DME are manufactured each year for uses in cosmetics and aerosal paint propellants. Its new use as a clean fuel source is gaining attention and research, as it contains no sulfur or nitrogen compounds, has a very low toxicity, and is not corrosive to metals. It can be stored and transported as a liquid at low temperatures
A single-stage, liquid phase synthesis process for DME in a slurry phase reactor system is efficient and facilatates heat removal. The combination of methanol synthesis and methanol dehydration reversible reactions in a single step is thermodynamically more favorable. The liquid phase operation allows for better heat management and higher yields of DME.
The first pictured reaction shows the methanol synthesized from carbon dioxide and it is combined with the second pictured reaction into the last pictured reaction, in which the synthesized methanol is dehydrated to produce DME.
See here for the CiteULike with the reactions and here for another journal article about DME. In addition, the catalytic synthesis of methanol is covered in Ch.10 of Wade and DME itself is discussed in Ch.14.
Saturday, July 16, 2005
A simple one-pot synthesis of β-alkoxy alcohols from alkenes
The main protocol for the synthesis of β-alkoxy alcohols is the alcoholysis of 1,2-epoxides. To synthesize epoxides, we can use oxone in the presence of transition metal complexes, or cyclodextrines, or via the formation of dioxiranes.
An application of this type of reaction is the synthesis of β-methoxy alcohols. It is done by the one-pot reaction of alkenes with oxone in methanol without any other catalyst.
Note: Oxone (2KHSO5·KHSO4·K2SO4) is the registered trademark from Du Pont.
General reaction and some examples are shown above.
For reference, please click on http://www.citeulike.org/user/hongan1985/article/258103
Chap 9 UT map ready for testing
I'll make these maps available on the network shortly but for now you have to download and play on your computer.
You can play with or without bots (or other players). So if you just want to calmly explore select no bots and don't play on the network.
If you don't have UT2004 but still want to play let me know and we can make arrangements.
Please report any errors or problems as comments on the Edufrag blog on the post of the map you are playing.
This is an example of a student assignment done as a map instead of a blog post.
Friday, July 15, 2005
Creating Amphetamines by Tosylation of Alcohols
The picture above shows a few of the steps in the creation of amphetamines. In these steps, tosyl chloride is added to (2,5-dimethoxyl-4-methylphenyl)-2-propanol to create the tosylate. After this step, the reaction can proceed in one of two ways. If the chirality of the amphetamine is not important, ammonia is added to the tosylate to give 2,5-dimethoxy-4-methylamphetamine. This reaction has an 80% yield, but has a racemic mixture of products because it is thought to be an SN1 reaction. If the chirality is important, the tosylate is converted into an azide with sodium azide, then hydrogenated using a paladium catalyst to form 2,5-dimethoxy-4-methylamphetamine. Forming the amphetamine using this method gives a final yield of about 77%. The chirality of the original alcohol is inverted by the tosylation, so reacting an (S)-alcohol with the tosyl-azide-hydrogen sequence would give an (R)-amphetamine, and vice versa.
For the full text of the article describing this process, see this report.
Saturday, July 09, 2005
First deadline grades
One general comment: use a specific reaction of a specific compound that you find in the article. Avoid drawing general structure with R groups.
Friday, July 08, 2005
The dioxygenase-catalysed formation of vicinal cis-diols
This is an example of the reaction of an epoxide ring reacting with water and and enzyme (epoxide hydrolase) to create a vicinal diol. The paper displays experiments with several different compounds and the role of mono- and di-oxygenase enzymes in arene
metabolism. The paper also displays a variety of intermediary or alternative pathways the the substrates can take to generate different, but useful products. The primary focus is on the impressive ability of bacterial oxygenases to catalyse the cisdihydroxylation
of a diverse range of arenes and alkenes to yield a single enantiomer.
Addition of Grignard Reagents to Ketones
This is an example of the reaction of a ketone with a Grignard reagent, which gives a tertiary alcohol. The paper presents a study of several different idol-3-ones reacting with Grignard reagents. Idol-3-ones are potentially useful intermediates in the synthesis of alkaloids and pharmaceutical agents.
Going one step further: due to the lack of stability in the tertiary alcohol, a rearrangement is observed on the alcohol molecule, creating a gain in resonance stabilization in the final molecule. The study examined a variety of conditions under which the rearrangement occurred, in order to recognize the most efficient one. It was determined that the rearrangement took place with great facility under acidic or basic conditions or was thermally induced.
CiteULike Quick Reference
Blog Picture Suggestions
1) In Flikr, before you obtain the URL click on the image which is bigger than the one that shows up in your album and then go to properties to obtain the URL. This image is larger to when Blogger formats it, the picture is more clear.
2) To make the picture even more clear: go into "Edit HTML" of your blog post when you edit it. Then find the line for your image that will look like this:
"http://photos18.flickr.com/22901961_b9fc681f83.jpg?v=0">="DISPLAY: block; MARGIN: 0px auto 10px; WIDTH: 320px; CURSOR: hand; TEXT-ALIGN: center" alt="" src="http://photos18.flickr.com/22901961_b9fc681f83.jpg?v=0" border="0" /
and delete the text in pink (width) from the HTML code. This will make the image a little more clear. If your image is too large though, it will extend out into the navigation on the right so make sure when you delete width that your image doesn't do that.
1) make sure your molecules and reagents are big enough to view easily from http://chem242.blogspot.com. See the first few examples that I graded "full marks" to see how big is big enough
2) you must use CiteULike
3) ALL of the reference info needs to be present in CiteULike (authors, journal name, year, page, volume, title, abstract)
4) the single step reaction that you have in your scheme MUST be in the article you are citing
I will shortly stop giving this feedback repeatedly and just grade it accordingly at each deadline.
If any student has tips (especially for making molecules the proper size in Chemsketch) it would be great if you could record a 1-2 minute screencast of it. Just download the trial version of Camtasia, save as an avi and I'll give you instructions to upload.
Synthesis of Ethylene Oxide as a fumigant
This shows the synthesis of ethlyene oxide which can be used as a fumigant for foods, textiles, soils and for sterilizing biomedical instruments. It readily diffuses through materials without damanging them. Its antibacterial effect is probably due to its ability to alkylate critical cellular enzymes.
Heres a link
Thursday, July 07, 2005
This is a nitrate ester made by esterification. In this process, glycerols reacts with Nitric Acid under a catalyst of Sulphuric Acid at 300oC to yield an ester complex of glyceryl trinitrate otherwise known as nitroglycerine, and three water molecules. In this process, there has been formation of an ester bond (COO). This production is very crucial for medical purposes. Nitroglycerine is used to relieve angina, a condition when the heart isn’t receiving much oxygen. Also, Nitroglycerine was used in a study with yohimbine/l-arginine combination to see the treatment of erectile dysfunction in males. The metrics used in this study were the male’s systolic and diastolic blood pressures. This study created a correlation between the effects of erectile dysfunction with the inadvertent cause of coronary artery disease. Intravenous Nitroglycerine was used to help in the study with the chemical compositions with arginine. Here is a reference for this article on its uses.
This is en example of what we learned in class, the Markovnikov hydration of n-propyne (a terminal Alkyne) that produces a Ketone. Using ACS publications, i found an article that describes an ideal anti-Markovnikov hydration of the same compound, to produce an Aldehyde instead.
To induce this reaction, the catalyst cyclopentadienylruthenium is used in a 2-Propanol solvent at 100 deg C, with yields over 99% for this reaction, other Alkynes bearing over 90% for the most part.
The Role of Phosphate Esters in Biochemistry (DNA and Cellular Processes)
The backbone of deoxyribonucleic acid (DNA) is composed of nucleic acids, which are made up of ribofuranoside units strung together by phosphate esters. These phosphodiester bonds (two ester bonds) create the DNA backbone.
This simple ChemSketch shows the linking of nucleotides in DNA via phosphate ester groups:
Phosphate esters are created when phosphoric acid and an alcohol combine. Here is an example with methanol (alcohol), which can form three esters based on how many moles of methanol are used:
In addition to its role in the backbone of DNA, phosphate groups play a biochemical role in ribosome-substrate interactions and the regulation of cellular processes. The regulation of their formation on key body proteins regulates these processes, and malfunctions in their regulation can result in cancer, diabetes, and even obesity.
Phosphate groups also play a major part in the bending of the DNA backbone, due to the repulsion of the negative charges. Other experimentation concerning the role of phosphate ester groups includes looking at their electrostatic contribution to the free energy of the bent DNA backbone as well as the synthesis of heparin-immobilized polyetherurethanes, whose side groups have hydrolysable ester groups (heparin being a synthetic anti-coagulent).
Here is reference one and reference two and reference three from CiteULink.
In addition, Chapter 11 and Chapter 23 from Wade provide substantial information on this topic.
Question about blog assignment
I've already fixed my post and uploaded the images.
I did not delete any comments that you made. On Wednesday after I posted the assignment, I checked the blog many times on the day and made some changes. But I still saw "No comments". I actually never delete any comments.
Do I need to correct anything else from my assignment? Do I need to redo it?
Blog Aassignment Help
Just follow the link bellow and log in with your Drexel ID to access the journal data base. Once at the site, go to the tab that says "search the journals." I used the "search journals" part to type in keywords such as reagents used, compound names, and you can even search by picking a drug of interest and seeing if there is an article on how it synthesized. The articles come in full text and I like using the HTML version because its easier to navigate and see the images.
The above is one of the final reactions in the synthesis of an enantiospecifically labeled fatty acid. It involves a reduction with Lindlar's Catalyst in the presence of deuterium, an isotope of hydrogen. Lindlar's Catalyst (powdered barium sulfate coated with Pd, poisoned with quinoline) converts an alkyne to a cis-alkene, as seen in the reaction above. The article I looked at focused on pheromone biosynthesis in S. isatideus and the role stereochemistry played. Article Link.
Interestingly, instead of retaining its chirality, the product of the pinacol arrangement actually resulted in a racemic mixture. Subsequent derivatives of this product eventually yield benzophenone (hydroxyphenstatin), which, biologically, is a potent antitumor and antimitotic agent. Accordingly, hydroxyphenstatin has also been proven to inhibit tubulin assembly. Article Link.
Wednesday, July 06, 2005
One problem occurs with aspirin is that it has a destructive effect on the blood vessel walls and inhibit the synthesis of prostacyclin. To resolve this problem, we can use potential anti-platelet agents including the O-acyl esters which are synthesized from salicylic acid and diflunisal. Those agents work by acylation of cyclooxygenase and have a higher extraction than aspirin. That makes them yield a greater selectivity in their effect on platelet inhibition relative to prostacyclin inhibition on vessel walls.
The actual reaction is shown on the top.
For reference, please click on http://www.citeulike.org/user/hongan1985/article/246557
Tuesday, July 05, 2005
More blog assignment info
2) You may not copy reactions or text from articles.
3) Pick one simple reaction that we covered and only draw that.
4) You may use ChemSketch or drawing on a tablet PC or drawing on paper and scanning the reaction if you have to but in the long run ChemSketch will come in very handy so might as well learn it now.
5) After uploading make sure that the pic is not too wide, as it will distort the right hand frame of the blog.
Quiz Ch. 10: Questions 3 & 9
9) CH3 MgBr + CH3CO2CH3 yield 2-methyl-2-propanol. But wouldn't an excess (xs) of CH3 MgBr yield CH4 and CH3COCH3 because the excess CH3 MgBr would react with the formed hydroxyl group on 2-methyl-2-propanol???
Monday, July 04, 2005
The most common medical ester is aspirin (ASA; acetyl salicylic acid). Other drugs such as Worm Guard (anti-wormer), Maxicaine (local anesthetic), Malathion (organophosphate), Mebendazole (antihelmenthic), Demerol (narcotic analgesic) and Equinil (sedative) are also esters.
The starting reactants for this experiment are salicylic acid and acetic anhydride (structures are shown above).
Salicylic acid reacts better with acetic anhydride than acetic acid, so acetic acid will provide the acetyl group which will react with the alcoholic -OH group on the salicylic acid. (The reaction is on the top of the post.)
Chemicals needed for the reaction: Salicylic acid, Acetic anhydride, and Concentrated sulfuric acid.
Equipment: 250 mL Erlenmeyer flask, Hot water bath, Ice bath, Buchner funnel and filter paper, Glass stirring rod, and Electronic pan balance and weighing boat.
For the full text, click on http://tooldoc.wncc.nevada.edu/aspirin.htm
Sunday, July 03, 2005
Catalytic hydrogenation of an ether to an alcohol
This is one of the synthesis steps to produce tolterodine tartrate. The focus of the study was to find a cost-effective and impurity-free process to produce tolterodine tartrate. This compound is a muscle relaxant used to treat bladder disorders. Although ethers are inert to most reagents, a benzyl ether, like the one above, can be hydrogenated under mild conditions (H2/Raney/Ni/MeOH/25-30 C) to an alcohol. The phenyl group stays and the methylbenzene group leaves. Article link.
Saturday, July 02, 2005
Eco-Friendly Halogenation of Alkynes
This reaction is a summary of an ecologically friendly process for halogenating alkynes. The reaction works with both hydrobromic and hydrochloric acid, and produces water as its only waste product. It also gives a good yield of the halogenated product.
Instead of undergoing anti-Markovnakov addition of HBr, the alkynes are halogenated. This is due to the way the reactants are mixed. Mixing a hydrohalogenic acid with a solution of t-butylhydroperoxide (TBHP) and hydrogen peroxide will oxidize the halogens, causing them to become positively charged. The charged halogens will then attack the alkynes, and a halogenation reaction will occur.
For the full text of the article describing this process, see this report.
Friday, July 01, 2005
Reaction of an alcohol with thionyl chloride (Ch. 11)
Reduction of an ester to an alcohol
Thursday, June 30, 2005
first deadline coming up
Monday, June 27, 2005
summer webct course active
If you are auditing the course, nothing has changed. Still use the guest account.
2) If I have made arrangements with you to be registered for this class, make sure you contact Amber to have you registered for CHEM242-900. You should be able to see the class listed in the summer term soon in WebCT. There is currently a problem with the WebCT listing in the summer term but everyone should have access to the Default Term listing either through your account or the guest account. Email me if you need the password to that. You can do everything as a guest except take the 2 tests and exam. Students auditing the class should use the guest account to log in at http://webct.drexel.edu
3) If you have a question, make sure to check the recorded lectures first, especially the review sessions. The quickest and easiest way to do that is to check the pdf or Powerpoint to get an idea or roughly where in the recording the explanation is likely to be. I spent a lot of time last term finding the location of student questions in the review sessions to answer email queries. My time is better spent answering new questions.
4) If you still don't see your question answered, then post it to this blog. Your questions have to be of the format "I am having trouble with converting x to y. Based on the notes, I was expecting the product to be p but that answer is not correct." Questions that don't indicate how you tried to solve the problem (e.g. "What is the answer for question 1 of quiz 1?" will be deleted. I would encourage other students in the class to attempt to answer the question as a comment to the post. This will only help you learn the material better.
5) The test dates will be scheduled shortly.
6) You may submit your 5% blog assignment as an Unreal Tournament Map (here is an example). This is definitely a more difficult project but could also be more rewarding to create [and to grade :)]. Contact me for details if interested in this option.
Friday, June 10, 2005
Chapter 10: 33-39.
Chapter 11: 41,42,44,48.
Chapter 12: 15-19.
Chapter 13: 33-41, except 37.
Chap 14: 30,31,33
Chap 15: 24,25,27,30
Chap 16: 27,28,32,34
Thursday, June 09, 2005
summer of 2005 introduction
All of you who are taking this class have just finished CHEM 241 with me. It will be similar but there are a few changes:
1) The class material is mainly on WebCT. A partial podcast of the audio files is available here. But the screencast, Powerpoint and pdf notes are in WebCT. Only Real Media files are available for the screencast at this time. You should have access to the class in your default term in WebCT. Make sure to click on "View all my WebCT classes" link if you don't see the class listed.
2) The FAQ for the class is the same as last term. Make sure you subscribe to it in case there is the odd post.
3) The syllabus is a bit different from last term - read carefully (next post).
4) This section is online only. There are no set meetings but if you get stuck send me an email or post to the blog (see 6 below). The first test will be around week5 and the second around week 10. Pace yourself so that you cover the material you need to for the tests.
5) I will be out until June 26, with no access to email. If you have any questions, save them for when I return and keep going through the material. In the meantime practice with the quizzes and problem sets. I have noticed that almost all questions I get from students are covered in one of the review sessions already recorded. Use the pdf to give you an idea of where in the screencast you should find the problem explained.
6) I will add you to the class blog to post your blog assignment (see syllabus in next post). If you wish to be anonymous just email me the username you chose. You may also post questions and comments to the blog. If I am not around another student might have the answer for you.
Monday, March 14, 2005
Thursday, March 03, 2005
test 2 chapters
Send me your questions for the review session on Friday morning.
Saturday, February 12, 2005
podcasting of mp3's now available
You must first download an aggregator like ipodder. Copy the above link in the field to add links then click on "check selected feed". Ipodder will automatically download mp3's as they become available. On your PC these files will show up in a folder called "My Received Podcasts" under "My Documents". I believe that if you have an ipod it will copy the files directly onto the device.
The nice thing is that the downloads happen in the background, as long as you are connected to the internet. Let me know how it works out.