Organic Chemistry II

The last race

noreply@blogger.com (Jean-Claude Bradley) — Sat, 18 Mar 2006 02:09:59 PST

The last UT race of the term was won by Nick, who automatically won the video ipod since it was the only prize left for him to win. This was probably the most difficult maze so far and took him 15 minutes to complete.

The Chemistry Behind Lightsticks

noreply@blogger.com (Tyler) — Fri, 17 Mar 2006 06:20:12 PST

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.”

Exam Quiet Time Reservations

noreply@blogger.com (Jean-Claude Bradley) — Fri, 17 Mar 2006 10:34:21 PST

Sunday March 19th Room B-103 3:00-9:00 pm
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
4-9 pm

frustrated winner

noreply@blogger.com (Jean-Claude Bradley) — Fri, 10 Mar 2006 09:12:17 PST

Nick won this morning's race in 10 minutes. This is his third win and he drew the molecular model set. The only prize left for him to win is the video ipod, since I don't give out the same prize twice to the same person. We'll do the final race of the term on Friday March 17, 2006.

This maze is all about IR and NMR and is a good way to review the material for the test and exam.

iPod won today

noreply@blogger.com (Jean-Claude Bradley) — Mon, 06 Mar 2006 06:44:27 PST

Louie won the video ipod in this morning's race in an impressive 4 minutes.

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.

Test 2 Reserved Room

noreply@blogger.com (Jean-Claude Bradley) — Mon, 06 Mar 2006 06:05:03 PST

Room F-111 has been reserved on Saturday 3/11/06 from 8-5 pm.

Feb 27 race

noreply@blogger.com (Jean-Claude Bradley) — Tue, 28 Feb 2006 07:51:38 PST

Monday's edufrag race was won by Nick again. He drew the book prize.

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.

next workshop

noreply@blogger.com (Jean-Claude Bradley) — Tue, 21 Feb 2006 07:17:57 PST

There will be no workshops this week until Monday Feb 27, 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.

Feb 17 2006 race

noreply@blogger.com (Jean-Claude Bradley) — Fri, 17 Feb 2006 07:43:00 PST

This morning's Unreal Tournament race was won by Raymond in 8 minutes.
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.

Fischer Esterification: 2-ethylhexyl benzoate

noreply@blogger.com (lkm92) — Thu, 16 Feb 2006 05:28:40 PST

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.

Click here for the full text.

Feb 13 2006 Race

noreply@blogger.com (Jean-Claude Bradley) — Mon, 13 Feb 2006 07:12:09 PST

Today's edufrag race is available for download here.

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.

Hock Process in the Manufacture of Phenol

noreply@blogger.com (Tyler) — Mon, 13 Feb 2006 10:29:04 PST

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.

Race on Monday - try to win an ipod

noreply@blogger.com (Jean-Claude Bradley) — Wed, 08 Feb 2006 06:12:44 PST

There will be an Edufrag Race using the educational version of Unreal Tournament on Monday Feb 13, 2006 during our workshop time at 9:00 in CAT 061. There will be 20 rooms in the maze on any topic from CHEM 241 and up to test 1 in CHEM 242.

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
book
consolation mystery prize

no workshop Jan 27

noreply@blogger.com (Jean-Claude Bradley) — Thu, 26 Jan 2006 09:26:21 PST

There will be no workshop tomorrow Friday Jan 27, 2006. We'll resume on Monday.

Powerpoint and Problem set downloading

noreply@blogger.com (Jean-Claude Bradley) — Tue, 24 Jan 2006 02:45:28 PST

There seems to be a problem with downloading files from WebCT Vista.

You may now download the Powerpoints and the problem set pdf off of the class wiki (Items 4 and 12)

Class Vodcast available

noreply@blogger.com (Jean-Claude Bradley) — Mon, 23 Jan 2006 07:23:59 PST

Subscribe to the class screencasts on your video ipod by dragging the vodcast icon (from the class blog) into iTunes. Even without an ipod, you can view the screencasts from iTunes on your computer.

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

noreply@blogger.com (Jean-Claude Bradley) — Mon, 23 Jan 2006 06:00:36 PST

Just a reminder that you should now be at the end of Chapter 10 problems and quiz and have had any confusion resolved at the workshops or by emailing me. You should have all technical issues addressed by now.

The first test is coming up in 2.5 weeks.
Remember that the Friday workshops are in Matheson 109.

First week update

noreply@blogger.com (Jean-Claude Bradley) — Sun, 15 Jan 2006 04:20:22 PST

1) Students who came to the workshops got all of their technical issues squared away and we worked on alkyne problems. A few students also worked on their extra credit assignments.

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.

Welcome Winter 2006 class

noreply@blogger.com (Jean-Claude Bradley) — Mon, 09 Jan 2006 01:58:08 PST

Your starting point for this class is the wiki. I will use the blog this term only for announcements and this is where your extra credit blogging assignments get posted. See the assignments from previous terms in prior posts here and look at the comments to see my feedback and grading system.

Last Blog Assignment Deadline Over

noreply@blogger.com (Jean-Claude Bradley) — Sat, 20 Aug 2005 04:34:58 PDT

All grades for the last blog assignment have been posted. It is now too late to add or change your posts.

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.

Bimolecular Dehydration of 1-Pentanol to Di-n Pentyl Ether (DNPE)

noreply@blogger.com (shailja) — Fri, 19 Aug 2005 07:59:21 PDT

Regulations controlling diesel exhaust become more exacting with each passing year. Accordingly, diesel fuel properties are constantly being analyzed in an attempt to further reduce fuel emissions. There are many options, most often refinement processes or improving the cetane number. Essentially, short and branched ethers (used in gasoline) have a good octane number but poor cetane number, while those ethers used in diesel are linear and have a comparatively long chain (ideally 9 or more carbons). Di-n pentyl ether (DNPE) has shown most effective in reducing emissions, and is also relatively simple to synthesize via the bimolecular dehydration of 1-pentanol on acid catalysts, as seen below.

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

noreply@blogger.com (jdf36) — Fri, 19 Aug 2005 14:14:30 PDT

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.

Free-Radical Polymerization: Alkoxyamine Initiators

noreply@blogger.com (Nicole) — Fri, 19 Aug 2005 11:03:37 PDT

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.

Here are articles about the Me6-tren ligand and its naming.

This source discusses the use of alkoxyamines in free-radical polymerization.

Diels-Alder reaction of Quinol Lactone

noreply@blogger.com (Petia) — Fri, 19 Aug 2005 18:42:43 PDT

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.

Zinc reduction of alkynes

noreply@blogger.com (atd36) — Mon, 15 Aug 2005 20:19:00 PDT

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:
http://www.citeulike.org/user/hongan1985/article/279061