The Chemistry of Cannabis: Detection of Cannabis Farms

*This blog post is purely for educational purposes. We do not support the production, distribution, or consumption of Cannabis.

Welcome back! So, since you’ve clearly been overwhelmed by the amazingness of the information in our blog posts, we think you deserve a refresher. In previous blog posts, we have discussed the effects thatCannabis has on the brain, and the different forms through which Cannabis can enter the body and results in these effects. In this blog post, we’ll discuss new and innovative ways that law enforcement is using to detect Cannabis farms.

Scratch ‘N Sniff™

(yes, you read that right)

A charity organization based in London, England has come up with an innovative way to help police officers locate Cannabis farms. The organization has created Scratch ‘N Sniff™ cards. These Scratch ‘N Sniff™ cards that mimic the scent of Cannabis in its growing stage, and are being distributed to English citizens so that they can to familiarize themselves with the smell of growing Cannabis and can notify the police if they detect the scent. So far, the organization has issued more than 200,000 scratch and sniff cards to hotspots in England, and, there has been a 28% increase in information from the public on Cannabis farms.

Now, how do these Scratch ‘N Sniff™ cards work? The ideas of chemistry can be applied to the Scratch ‘N Sniff™ technology through the ideas associated with entropy. Entropy is the number of ways a system can be arranged. In this case, aroma molecules that are microencapsulated are at a state of low entropy, since they are enclosed in minute capsules. The manufacturing process of scratch and sniff cards utilizes this entropy idea. The diagram shown below illustrates the process. In general, the process includes taking the aroma-generating chemical and encapsulating it in gelatin or plastic spheres that are a few microns in diameter, and this traps the odor. A certain chemical catalyst is used to bring about the reaction which finalizes the encapsulation of the odor. In other words, the catalyst is the metaphorical “kick in the pants,” or the thing that bring about the reaction. This  reaction requires a “kick in the pants” because it will not happen on its own; this type of reaction prevents particles from diffusing, as they would “like” to, and in order to get particles to do something they don’t want to, you have to bribe them with energy.

When these capsules are given another metaphorical “kick in the pants,” or an activation energy, they are released and they dissipate and spread the scent. Even though the particles want to diffuse, a “kick in the pants” is required to give them enough energy to break through the capsule. This energy required to get this reaction going comes in the form of kinetic energy from a person, when he/she scratches the card, applying friction to the capsules. The aroma molecules are then released, and since they have more volume to diffuse into, they achieve a higher state of entropy.

This idea of  Scratch ‘N Sniff™ technology, then, can support the notion that the entropy of the universe is always increasing. Spontaneous reactions, which have a negative free energy value, are constantly occurring in the universe. The Scratch ‘N Sniff™ system is one primary example of this chemical theory. Since this technology embodies the principles underlying entropy, then it also applies to The Second Law of Thermodynamics. This law states that “In an isolated system, natural processes are spontaneous when they lead to an increase in disorder, or entropy.”

Thermal Cameras

Tower block thermal image

Authorities are beginning to use thermal cameras to detectCannabis farms. Often, Cannabis growers employ heat lamps when growing indoors. Further modifications to the growing area typically include the addition of ventilation and irrigation systems. Thermal cameras are being used to detect growers who hideCannabis around other plants, rendering them invisible to the naked eye. However, the grower must make some changes to the soil, which allow these cameras to detect hidden plants. The soil is turned over and the vegetation around the plant is trimmed off to allow for better absorption of water and nutrients. As a result the soil also absorbs heat at a higher rate than the other surrounding plants. Consequently, they stand out in thermal scans.

Just like any other camera you use, thermal cameras detect light. However, they differ from conventional cameras in that they detect different wavelengths of light. Thermal cameras detect infrared light as opposed to visible light. Because the lamps generate heat, the system emits infrared radiation. At the atomic level, the heat is simply the movement of particles. When the particles collide with each other, they can affect each other and induce a dipole oscillation. Due to this volatile distribution of charge, electric and magnetic waves are emitted as photons within a certain range of frequencies. Finally, the hotter an object is, the shorter the wavelength it emits. Thus, thermal cameras display hotter areas closer to white and darker areas closer to black. Also, if an object is hot enough it can emit thermal radiation that is visible to the human eye, a simple example being fire.

Well, that’s all folks!

Essentials of Fragrance Chemistry

By Matthew Tittensor, Nicholas Lang, and Sohum Sanghvi

Two more common hygiene products are perfume and cologne.  We know that these sprays smell nice and permeate throughout a room, but what is it that gives them their scent and more importantly why does it disperse?  In today’s blog post we will get into this by discussing the organic structures of esters, specific scents, commercial uses for esters, and the process of diffusion.

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           An ester follows the format follows the format of the image to the right, with the R group being any hydrocarbon.  This is written a RCO2R’.  The alcohol component makes up the basis of the alkyl component and R’OH’s root name and is based on the longest chain with an OH attached to it. Meanwhile, RCO2H is the carboxylic acid, from which the –oate in the name is derived from.  The full name for an ester is an alkyl alkanoate. Now that the nomenclature is out of the way, what do esters smell like and would they be used in perfumes?

Esters often have a pleasant fruity aroma as can be seen in the chart to the right.  However, that does not necessarily make them ideal for perfumes.  Most simple esters give off these pleasant smells, but problems arise because they are not prepared to handle the sweat that a human body releases.  This sweat hydrolyzes the simple ester and can replace this seemingly nice smell with a harsh one.  A common example is that butyric acid smells like rancid butter, but ethyl butyrate, an ester it can be derived from, smells like pineapples.  This is one reason that simple esters are not utilized in the perfume industry.  However, perfumeries get around this by often including many esters in their products as well as essential oils to prevent the hydrolysis of the esters.  Esters serve a role in the food and beverage industry as well.

           Would you rather eat a delicious food that smells rancid or a mediocre food that smells delicious, if you did not know how each one tasted?  This is a problem that major manufacturers come to face when they make their products.  These companies utilize a combination of esters and essential oils as well to produce a scent that is please to both smell and taste.  It is not so simple as getting one pleasant odor and taste either, as the human has over 9000 taste receptors on its tongue and smell plays a large role in perception of taste.  To create an ideal, it takes a lot of testing and a wide variety of organic and synthesized compounds to be used.

           Diffusion is the movement of molecules from an area that contains a higher concentration to one with a lower concentration of the molecule.  These molecules are already in constant motion and move in random directions due to the random collisions that they experience with each other and other particles.  The net movement is always towards the lower concentrated expanse as more collisions occur on a more highly concentrated zone, making it more likely for the molecule to be pushed over to the other area.  Dynamic Equilibrium only comes to exist after the concentration gradient, difference in molecule distribution, is removed.  This applies to perfumes and colognes as they emanate from their more highly concentrated location on the wrist or neck to the areas surrounding the wearer.  This creates a nice scent around the user and fulfills the purpose of removing or covering up body odors.

http://www.hartnell.edu/tutorials/biology/images/cell%20environment%20diffusion%20fig.jpg

We have taken a look at the concept of esters, specific scents, commercial uses for esters, and basics about the process of diffusion. Using the right ester is vital for obtaining the scent that is wanted, and diffusion is important for making sure the scent remains on the user and covers the body odors. In our next blog post, we will continue our discussion on fragrances and continue to unveil interesting chemistry behind perfumes and colognes.

Balls from Fury: Buckminsterfullerene (C60)

  There’s a molecule out there that can hit a stainless steel plate at 15,000 mph and just bounce back. It’s the state molecule of Texas, if that says anything. And you probably already know what it looks like. If you said the molecule is a buckyball, you’re correct. Buckyballs, specifically C60, look almost exactly like a regulation soccer ball, in order to produce extremely stable sp2 bonds throughout all 60 of the

http://www.godunov.com/Bucky/buckyball-3.gifhttp://www.clker.com/cliparts/3/7/d/5/1197103862376117882Gioppino_Soccer_Ball.svg.med.pngcarbons. Buckminsterfullerene, the more technical name for buckyball, was based on the domes of world famous architect Buckminster Fuller. The purported structure of C60 upon its discovery looked remarkably like many of his domes (well, more like B80but that’s another story).

Buckminsterfullerene has a density of 1.65 g/cm3. In its solid form it takes on the appearance of rather dark, needle-shaped crystals. It won’t stay that way for long, for it sublimes at around 800 K. Being that it’s made up of all carbons, it’s a nonpolar substance; it won’t dissolve in water, and it’ll barely dissolve in other nonpolar substances like benzene. When stimulated with life, it prefers to act as an electron acceptor, in the same manner as an electron-deprived alkene. Unless it’s in solution, it doesn’t prefer to be reduced, with each individual reduction from C60 to C606- being negative and approaching the penultimate -2.549 V at the final reduction at 213 K. It does prefer being oxidized, however, at very low temperatures, though past C60+ the products tend to be rather unstable. And here’s a kicker–buckyballs are the largest known molecule to exhibit wave-particle duality (at least in a diffraction grating). It’s a wonder we’ve even discovered a molecule with these properties; in fact, mostly everything about this molecule is still a wonder.

 One of the Best Accidents?

 C60 became nothing short of a chemist’s dream come true upon its discovery in 1985. Yet, it was discovered purely by accident by H.W. Kroto, J. R. Heath, S. C. O’Brien, R. F. Curl & R. E. Smalley at RICE University in Houston, Texas. The understanding of how long chains of carbon were formed in interstellar space was sought. Lasers shot at a rotating disk of graphite in concentrated helium, and… well, the researchers ended up being inevitably shocked. Sure, they found molecules containing 40 or more carbons, but most prominent was the presence of 60 carbons (followed by 70). Conventional structures did not seem to work in having a molecule of 60 carbons be stable, so they sought alternatives. One structure they noted is as follows: “the C60 molecule which results when a carbon atom is placed at each vertex of this structure has all valences satisfied by two single bonds and one double bond, has many resonance structures, and appears to be aromatic.” Even by this alone was the structure hinted at. They hypothesized that “fragments are torn from the surface as pieces of the planar graphite fused six-membered ring structure. … When these hot ring clusters are left in contact with high-density helium, the clusters equilibrate by two- and three-body collisions towards the most stable species, which appears to be a unique cluster containing 60 atoms.” They even specified the diameter of the molecule, 7 angstroms, which was enough to stick an atom inside. The rest of the chemistry world found this discovery to be nothing short of awesome, and Kroto, Curl, and Smalley were awarded the 1996 Nobel Prize in Chemistry for this.

The only issue in the discovery was that the initial method of production failed to produce substantial quantities of buckyballs. 5 years later, a technique using the evaporation of graphite electrodes in a light atmosphere of helium emerged, allowing for the mass production of buckyballs. Or, as discovered later on, one could just sublime the buckyballs out of graphite.

Possibly the Only Ball Safe for Human Consumption

    In these previous 29 years of existence buckyballs hhttp://www.goalfinder.com/images/SCCPRO16/Medical-application-of-buck.jpgave found potential uses in this world. For instance, doping a buckyball with potassium results in a superconductor that is functional at temperatures of 18 K, which a high temperature for a superconductor. Moreover, there’s evidence to show that buckyballs can bind to the insides of the protein HIV protease, effectively inhibiting their function and not allowing the HIV virus to replicate. And they may be even useful antioxidants. Buckyballs have a tendency to act as an electron reservoir; they can give free radicals (molecules specifically desiring an electron to become stable) the extra needed electron in order to stop them from taking electrons from other molecules inside the body. Plus, C60 is known to not be toxic to human cells, and it has the ability to go inside of cells rather easily. In fact, there’s olive oil with buckyballs dissolved in it at a concentration of 45 mg/50 mL on the market.

You Might Want to Duck

 http://www.rsc.org/images/buckyball-250_tcm18-187164.jpg

Even when leaving the confines of Earth, buckyballs were from its discovery speculated to exist in interstellar space, specifically because it has the ability to form in some of the mostadverse conditions known to exist. One theory about its formation is that UV irradiation takes PAHs (polycyclic aromatic hydrocarbons) and converts them to graphene and then into buckyballs. This is seemingly more efficient than an alternate explanation, one in which carbon atoms clump together in the hot, dense center region of stars.

The first place that buckyballs were found in (along with hydrogen) were planetary nebulae. Three nebulae with dying stars like ours contained these buckyballs; what makes this remarkable is that these stars were in our own galaxy. (Even more so, there was a nearby star containing buckyballs in a mass of nearly 15 times larger than that of our own moon). Nebulae are emitted by dying stars; in the middle of all the layers of gas being shed there is a white dwarf holding it all together. There is a stage where the white dwarf spits out a lot of carbon. Even more astounding was the hydrogen it was found with: researchers had previously assumed that the presence of hydrogen would cause it to form the chains and rings originally sought after. And that was just in the gaseous form: in 2012 it was found in solid form. What that means is not yet clear, but it can imply that it might have been a building block of life.

You’re probably sitting there shaking your head. So what if a molecule’s been found in space? It probably isn’t of much importance, is it? All these claims are surely false. Wrong. Buckyballs have been found in meteorites. Meteors, being the huge hunks of rock they are, have the ability to house materials not seen and never before seen on a planet. When they become meteorites and slam into Earth, not only does the resulting collision cause adverse climate changes (which no organism really likes, as evidenced by mass extinctions usually brought along with them) but it can also spread those materials all over Earth.

As stated at the beginning, a buckyball can hit a stainless steel plate at 15,000 mph and just bounce back, and it can also house atoms or even molecules inside. For instance, there was anasteroid impact marking the end of the Permian period, which took out nearly all life on Earth. The meteorite has been found to contain buckyballs housing helium-3 and helium-4, with helium-3 now being present in the atmosphere.http://www2.warwick.ac.uk/fac/sci/physics/research/condensedmatt/imr_cdt/students/kelvin_goh/endofullerenes/h2oc60/h2oc60_html_m71ddaf4.png?maxWidth=292&maxHeight=239

“Buckyballs are carbon molecules in the shape of a cage and they are very tough and hard to destroy,” said Kris Sellgren, a professor of astronomy at The Ohio State University in Columbus, OH.  She noted that although life forms, let alone a single molecule of DNA, absolutely dwarf a buckyball, “single atoms or small molecules can become trapped and can survive inside the cage while the buckyball safely travels through the harsh conditions of space.”

“Buckyballs with extraterrestrial gases trapped inside them, for example, have previously been found in meteorites that have slammed into Earth. Spotting buckyballs in interstellar space also reveals that relatively big molecules can persist and maybe even form in the diffuse, unforgiving voids between the stars.” These are something your regular soccer balls can’t handle.

Chemistry of Flow Batteries

Technology is progressing more and more with each passing day. In order to support these changes, advancements regarding power supply must also be made. At the moment, the trend is moving towards more efficient and sustainable sources of energy. The rechargeable, low-cost, and long-lasting flow battery seems to fit the bill perfectly. Of course, it is not as well known as the common lithium-ion battery because it is used on a larger scale rather than for small everyday items. It can be used to store excess electrical grid power which is then released during periods of high demand.

When you hear the word “battery”, the first thing that comes to mind is probably a package of AA or AAA batteries — you know, the ones with the adorable Energizer bunny on the front? Flow batteries are neither portable nor small. In fact, they consist of two liquid-filled tanks that are separated from the actual cell of the battery. These “tanks”, or electrolyte reservoirs, pump liquid electrolytes into two half cells separated by a membrane, as can be seen in the image below.

A reduction reaction takes place on one side and an oxidation reaction in the other, similar to the reactions within the fuel cells we mentioned in our last post. The membrane between the two half cells  keeps  the electrolytes separate, but is thin enough to allow certain ions to pass through in order to complete the redox reaction. Ions from both sides flow through the membrane and react with the electrodes on both sides of the cell, drawing energy from them. To store more power, the batteries can be stacked in a bipolar arrangement. At this point, they essentially provide unlimited electrical storage capacity. The only limit is the capacity of the electrolyte reservoirs.

Sounds pretty simple, right? Now for the interesting, and slightly more complex, part: how the actual energy storage takes place. The liquid electrolytes that flow through the cell are mixed with energy storing materials such as iron, vanadium, zinc, or bromine. Zinc-bromine flow batteries, for example, have a zinc anode in one half cell and a bromine cathode in the other. Aqueous zinc bromide is circulated through the two half cells. In discharge, (bottom image on right) a load is applied to the cell and the zinc metal on the anode is oxidized (Zn(s)↔ Zn2+(aq) + 2e) to form zinc ions and bromine is reduced to bromide ions at the cathode (Br2(aq)+ 2e ↔ 2Br(aq)). When the battery is completely discharged, the metal zinc on the anode dissolves in the electrolyte. It is stored there until the battery is recharged (top image on right), during which the reactions involving zinc and bromine are reversed. The zinc ions are reduced back to metal (Zn2+(aq) + 2e– ↔ Zn(s)), thus plating metallic zinc back onto the electrode. On the cathode side, bromide ions are oxidized into molecular bromine in the aqueous solution (2Br(aq) ↔ Br2(aq) + 2e) which combines with an oil to form a dense, oily liquid called a polybromide complex. As more polybromide complex is created and more zinc metal is plated onto the anode, the energy stored in the system increases. Because there are always fresh electrolytes in both half cells, the system is always ready to produce full power, even when the pumps are off. The electrodes in the zinc-bromine batteries don’t take part in thereactions but rather function as substrates, so repeated cycling won’t cause the electrode materials to deteriorate, as it would in most other rechargeable batteries.

So far, flow batteries seem like the best option available. The only problem is that they’re not quite available — not commercially, at least. Right now, the main issue is cost. The most commercially developed flow battery utilizes the rather expensive metal vanadium. For this reason, a team of Harvard researchers have recently developed a new type of metal-free flow battery that instead uses organic molecules called quinones, specially those found in rhubarb. According to Harvard author Roy Gordon, there is a limited number of metal ions that can be put into solution and used to store energy, none of which can store large amounts of renewable energy. For this reason, researchers have turned to organic molecules. The quinone used by the Harvard team is known as 9,10-anthraquinone-2,7-disulfonic acid (AQDS). What is unique about AQDS is its capacity for rapid reactions. It is able to undergo quick and reversible two-electron two-proton reduction on a glass-like carbon electrode in sulfuric acid. Although the small battery prototype has only run through about a hundred cycles, so far it has exhibited little to no losses. The model displays nearly the same performance as vanadium flow battery, but is much less expensive.

Flow batteries have a promising future, though they are not widely available at the moment and there are still unresolved issues regarding cost and production. Eventually, large quantities of energy will need to be stored and conserved in order to sustain our population and the great demand for power. Flow batteries will undoubtedly provide the best and most efficient solution.

Problems Arise: Balloons are Inflating the Helium Shortage

 

              It sounds ridiculous to think that something used everyday in birthday parties is in a serious shortage, but helium, an element used in applications ranging from balloons to MRI scanners, is now getting very difficult to find.  That means that very soon, your cousin may have a very disappointing birthday party. Yet that is the least of our problems.

              The most surprising thing about this shortage is that helium is the second most abundant element in our universe.  However, most of this helium is, practically speaking, way out of our reach.  Let’s embark on an exploration of helium to see why it is so hard to find, what Helium does for us, and what we can do in the future to make the search for it a little easier.

              The main trouble that arises when trying to obtain helium is that it’s less dense than air. This means that any helium trapped under the Earth’s surface eventually diffuses into the atmosphere. Once it’s in the air, it’s out of reach; we have yet to create a feasible means of collecting all of this diffused helium.  Currently, a huge build-up of Helium-4 (He-4) is being released in Yellowstone and about 60 tons of helium are released every year.  Some of this helium is diluted into the atmosphere, but the rest of it escapes the atmosphere into space.  Although it seems like we are letting this helium go to waste, there is just simply no viable way to collect it.

                                                                   yellowstone He.jpg                                                                                                                                                   Yellowstone National Park

              Yet there are other factors that contribute to Helium’s shortage. For one, the production of Helium as a by-product of nuclear decay is not a heavily invested means of production. This is largely because it is not an economically viable option (along with capturing the diffused Helium in the air as mentioned before); however as we will see, the value of Helium just may be priceless.  Another factor contributing to the shortage is the fact that in the past few decades, the demand and use of Helium has skyrocketed, largely ascribed to our squandering ways. With a limited amount, prices of Helium have soared as well.

              So why exactly is helium important anyway?  Helium has a multitude of applications, but its main application is its use to cool superconducting magnets in MRI (magnetic resonance imaging) scanners. Superconducting magnets are magnets that can produce immense magnetic fields, which MRI scanners require to operate and use to construct images of the body. MRIs use superconducting magnets because below a certain temperature, known as a critical temperature, a metal loses its resistance (The reason this happens at low temperatures is because there are lower energy and less frequent atomic collisions). This temperature needed for superconductivity requires cryogenic temperatures.  That’s where helium comes in.  Liquid helium, due to its extremely low (4.2 K) boiling point and high thermal conductivity, is very efficient at capturing heat and is the only medium that can induce superconductivity in metal alloys. In MRI scanners, the wires are bathed in liquid helium at -269.1 °C to capture heat and remove it from the system. This effectively removes the wires’ resistance and allows them to become superconductors. However, a normal MRI scanner uses 1,700 liters of helium which periodically has to be changed. This is a huge amount of helium, especially with the impending shortage. A new method of superconductor cooling was recently developed by a company known as Cryogenic. This method uses a significantly lower amount of helium and may soon significantly reduce the amounts of helium that we waste.

                                                                 MRI.jpg

                                                                                 MRI Scanner

              Another important application of helium is its use in oxygen tanks for underwater diving.  Normally air is comprised of approximately 20% oxygen gas and 80% nitrogen gas. Nitrogen gas is a lot more soluble than Helium, and is especially soluble at high pressures – which essentially keeps the gases in solution. The difference in solubility between the two plays a key role in why Helium is used, and is due to their difference in size. In order to dissolve any substance into a solvent, the solute and solvent must have interactions with one another. For non-polar gases like N2 and He, it becomes difficult to create the interactions with polar water molecules. To actually bring one of these gases into solution, an induced dipole must be created in the gas. An induced dipole becomes increasingly easier as the molar mass of the substance increases. This is because there are then more electrons to shift between the atoms thereby creating a strong bond between the solute and solvent. Between N2 and He, nitrogen gas clearly dominates in molar mass and strength of LDF forces. So at these high pressures below the water, the nitrogen gas becomes highly soluble in the bloodstream inducing nitrogen narcosis, a state with similar effects to those of alcohol. Furthermore, as divers begin to rise from the water, the solubility of nitrogen decreases and begin to bubble out of solution (the blood). This is extremely dangerous as it can create bubbles in the bloodstream which wouldn’t be able to pass through fine capillaries in the body. The condition, called the Bends, is life threatening. To prevent this from happening, Helium is used. As stated previously, Helium is less soluble than Nitrogen, so less Helium would get into the bloodstream. Furthermore, Helium is an inert gas, so its narcotic properties are negligible and do not pose any problems of toxicity like Nitrogen does. Helium continues to be the most ideal gas for diving tanks, and the shortage poses a serious threat to the maritime industries.

              With such versatility it seems more likely that the United States will take on currently, non-viable means to produce Helium rather than drastically cut down on usage. There will likely be 3 primary sources that will serve the United States in the future as a source of Helium. As stated before the first source would be through nuclear reactions.  One reaction that results in a formation of a helium atom is plutonium decomposition (Pu-239).  A plutonium nucleus decays into an alpha particle and a uranium nucleus.  The alpha particle immediately captures 2 electrons from the nearby plutonium metal and becomes a helium atom in the midst of a plutonium lattice.  There are 2 main problems with this method of producing helium.  Firstly, this process has a half-life of 24,100 years.  Using the half-life formula for first-order reactions, one could calculate k to be (ln2)/t1/2 = (ln2)/24,100= 2.88 x 10-5.  Using the first-order integrated rate law, one could determine that in a year, 10,000 g of plutonium will decompose to 10,000 x e-2.88×10^-5 = 9,999.71 g.  Therefore, in a year, 10,000 g of plutonium will only decompose to 0.29 g of decay.  That’s a measly 0.0029% decay after an entire year.  This makes generating a profitable amount of helium unfeasible to say the least.  The second problem with this method is that once the helium is produced, it is stuck in the plutonium lattice.  This makes it become very difficult to isolate and extract

              The second source is actually through natural gas. Some natural gas contains amounts of Helium that can be extracted through a complicated process. The reason it is not widely used today is because the extraction process requires strict criteria and many samples of natural gas only contain about 0.3-1.9 percent Helium by volume. Furthermore, there are many economic considerations before uptaking such a project as the extraction process requires facilities. However, in essence there are 3 steps to the extraction process. The first step is to remove the impurities from the natural gas such as water, carbon dioxide and hydrogen sulfide through means such as amine and glycol adsorption. The second step is to extract the high molecular-weight hydrocarbons. Finally, through cryogenic processing the remaining methane gas is extracted. This works because Helium has the lowest freezing point of any element. So as the temperature is sufficiently reduced, all other substances will freeze and can be filtered out. What’s left is crude Helium, containing approximately 50-70% Helium and the rest is Nitrogen gas and other traces of gases. To further purify the Helium to approximately 99.99% purity, Pressure-Swing Adsorption (PSA) is used. PSA separates different gases from each other based on the premise that each gas has a different affinity for different adsorbent materials, and have different vapor pressures. Due to the varying vapor pressures, one gas can be completely transformed into the gas phase at one temperature and pressure and then extracted, while the other gas would remain largely as a liquid.

                                        adsorption.png                                                                                                     Pressure Swing Absorption Process

              The final source will actually be where Helium is most abundant: outer space. Observations from lunar missions have concluded that there are about 22 grams of helium in every cubic meter of lunar soil. In the future, if Helium were to ever run dry on Earth, this alternative would likely create a madman’s dash to the Moon in search of this precious yet scarce gas.

              In essence, our lavish uses of Helium without a steady state of supply has caused a shortage that affects many scientific disciplines that rely on the unique characteristics of Helium. As a human race, we must either cut down on our uses of Helium in some shape or form, or begin taking measures to create more Helium for use in the future. Without Helium, many of the opportunities and technology today will float adrift tomorrow, just an arm’s length away from humanity’s struggling grasp for the resources we use so plentifully.

Instruments and Chemistry: Rosin

 In the previous post, we talked about how certain chemicals have properties that allow them to be suitable for maintaining certain instruments. For this last post, we will further explore maintenance, as well as the chemistry behind certain chemicals since they are both complex and vital. Out of the chemicals that are used, rosin is the most complex since it is comprised of various organic and inorganic compounds. The following image shows how complex rosin can be, as well as showing how it is manufactured from the resin found inside trees. The central column only shows two possibilities that the four isomers can undergo since two molecules can be formed by simply arranging one of the bonds next to the additional Hydrogen.

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          As one can see, the structure of the original organic compound varies by the location of the two double bonds, causing different concentrations of different acids to be present. These isomeric resin acids belong to the category of tricyclic diterpenes, whose basic structures result from the coupling of four C5-isoprene units (isoprene = 2-methyl-1,3-butadiene). The resin acids are distilled through 20% volatile turpentine and then leave behind some of the needed colophony rosin. However, some non-volatile alcohols and keto compounds are left behind and leave the molecule less pure and stable, so the compounds must undergo steam distillation in order to rearrange the atoms. Mechanistically, the rearrangement entails protonation at a terminal carbon atom of the conjugated double bond system, leading to a resonance-stabilized carbocation. The latter, through proton-transfer to the neighboring (allylic) CH2-group generates a rearranged diene, an unsaturated hydrocarbon with two carbon double bonds. The product ratio in the resulting equilibrium mixture is determined by the relative stabilities of the different conjugated dienes, and the stability gives the rosin the favorable properties that were mentioned in the previous post. While the acids in the final product are more concentrated, they are more stable and pure due to the addition and relocation of the Hydrogen atoms. The original resin is only 72% pure, while the final rosin is 95% pure; the rest of the percentages are non-volatile solids that hinder the rosin’s physical properties. This is why the levopimaric acid is the only substance that becomes less concentrated: it is the least volatile acid out of the four main acids that appear, and it slightly lessens the quality of the rosin as a whole. However, it is needed since the durability of the rosin can be attributed to this acid in particular.

          One of the most important chemicals used in the production of a piano is called lacquer.  Lacquer is more or less a wood polish; it is the chemical added to wood to give it the smooth and shiny properties.  Without it, the wood of a piano would be a lot more difficult to work with, shrinking the lifespan of the common piano by years if not decades.  Without lacquer, the piano and other hammered string instruments may have never become the influential instruments they are today.  But what exactly is lacquer?

          Lacquer is a polymer of many different bases that when coated on a wooden substance, offers a layer of protection and gloss to a piece of wood. The most common lacquer used on piano frames is a urushiol-based lacquer. Urushiol is a common allergen found in many Anacardiaceae plants such as poison ivy.  It has a boiling point of
200˚ C (392˚ F) and can dissolve in substances such as alcohol.  It is composed of a 6 carbon ring with 3 double bonds similar to benzene, 2 hydroxyl groups, and an R group. The R group varies from a large amount of hydrocarbons (such as (CH2)14CH3, (CH2)7CH=CH(CH2)5CH3, (CH2)7CH=CHCH2CH=CH(CH2)2CH3and others).  While harmful to many humans on poisonous plants, urushiol offers a special breed of polymer that can be used as piano frame lacquer.  It is a special type of lacquer in the sense that it settles in a more elaborate and controlled way. While most lacquers dry solely by evaporation, urushiol-based lacquers will oxidize with the air surrounding it and undergo polymerization.  This requires the settling process to be in a humid and warm environment, to avoid any evaporation.  However, if done properly, this lacquer will offer a completely optimized layer of shiny aesthetics and protective lifespan to the frame and other wooden pieces of a piano.

          As mentioned in the string section of our last blog, the best cleaning agents for brass instruments tend to be Trichloroethylene (TRI) and Perchloroethylene (PERC).  Last time, we talked about greases and oils for brass instruments, but sometimes build-ups of these compounds can form in sludge-like globules inside our instruments.  For degreasing and all-purpose cleaning, TRI and PERC are excellent reagents.  These compounds are heavy, maintain constant pH while cleaning, and dissolves quickly due to high solvency. It should also be noted that without adding stabilizing factors, these compounds are rather unstable and can react violently with metals, especially those made from Aluminum and/or Magnesium. These stabilizing factors are also able to protect Aluminum against decomposing.  In addition, more recently ultrasonic cleaning of instruments has been used instead of the degreasers.  This method takes advantage of a phenomenon called ultrasonic cavitation.  When water (or another liquid) is bombarded with the correct ultrasonic frequencies, very small bubbles form causing agitation. This extreme agitation can loosen contaminants sticking to a metal surface.  Adding certain ions to the water can greatly increase the rate of the reaction by reacting spontaneously with the contaminants with the added energy from agitation.  Finally, in the case that you would need to remove the lacquer from your brass instrument, acetone will work well.

Synthesis of Antibiotics

     Antibiotics are agents that are used to kill microorganisms or inhibit their growth. They can either occur naturally or can be synthetically produced. Extremely common today are semi-synthetic modifications of natural compounds. These chemical, biosynthetic antibacterial compounds are classified according to their biological effect on microorganisms. Bactericidal agents kill bacteria altogether while bacteriostatic agents slow down or stall bacterial growth. One specific semisynthetic antibiotic is what is known as Erythromycin.

     Erythromycin is what is considered a macrolide antibiotic. Macrolide antibiotics slow the growth of and often kill sensitive bacteria by reducing the production of important proteins needed by the bacteria to survive. This drug is notorious for being similar to penicillin in what it is used for and how it is synthesized. Often it is used as a substitute for people who are allergic to penicillin being that penicillin is such a common allergy. It is commonly used to treat respiratory tract infections, acne, Gonorrhea, Chlamydia, and other STDs. It is also applied to the eyes of newborn babies in order to prevent ophthalmia neonatorum. Erythromycin works by improving gastric emptying as well as its symptoms, though oral use of this drug is generally for short term use rather than long term.

     The chemical structure of Erythromycin, C38H69NO12, is extremely complicated and elaborate. Its synthesis published by Robert B. Woodward in 1981, the drug consists of a 14-membered lactone ring along with ten asymmetric centers and two sugars, L-cladinose and D-desosamine. The compound’s complexity makes it extremely hard to produce synthetically therefore it is produced by the bacterium Saccharopolyspora erythraea. Synthesis of this drug includes an intricate series of reactions. Reactions include hydrolysis and stereospecific aldolization. Oxidations and reductions are also involved in the synthesis by the pure enone’s conversion to desired dithiadecalin product. This product is further converted to ketone as well as an aldehyde. Overall, the synthesis contains roughly 50 steps split into 4 parts.

     Erythromycin comes in 4 forms: Erythromycin A, B, C and D. Erythromycin A is known for being the most antibacterial, with B, C and D following respectively. As discussed previously, this drug is considered to inhabit bacteriostatic activity, otherwise it inhibits growth of bacteria rather than stopping it or killing in completely. Its bacteriostatic capability is most displayed at high concentrations by interfering with aminoacyl translocation. This process objects to the functionality of important proteins, which is overall how antimicrobial action is put in place. One should be aware of the side effects erythromycin may cause, for example, abdominal pain, nausea, diarrhea, and vomiting.

     Zithromax is a semi-synthetic antibiotic, an example of the subclass, azalides and slightly differs in structure from the classical macrolides. It is used to treat and prevent infection within an area thought to be caused by bacteria. Like all other antibiotics, zithromax has an active ingredient, which in this case is azithromycin, a subclass of macrolide antibiotics. Azithromycin is derived from erythromycin but differs chemically from erythromycin in that a methyl-substituted nitrogen atom is incorporated into the lactone ring and is has improved activity through its glycosylated side chains. In this form, it has a molecular formula of C38H72N2O12. However, when Azithromycin is a dihydrate, which means it contains two molecules of water or its elements, it has a molecular formula of C38H72N2O12*2H2O. Also, Azithromycin contains inactive ingredients such as pregelatinized starch, lactose, sucrose, sodium phosphate, hydroxypropyl cellulose, or xanthan gum that all supplement the active ingredient.

 

     Azithromycin binds to 50s ribosomes and interferes with protein synthesis but does not affect nucleic acid synthesis. It binds to the 23S rRNA of the bacterial 50S ribosomal subunit, which includes the activities such as catalyzation of  peptide bond formation, prevention of premature polypeptide hydrolysis, provision of a binding site for the G-protein factors, assistance of protein folding after synthesis. blocking of protein synthesis by inhibiting the transpeptidation or translocation step of protein synthesis and by inhibiting the assembly of the 50S ribosomal subunit. Azithromycin was the target of an enantioselective synthesis, which is a chemical reaction where one or more new elements of chirality,a molecule that has a non-superposable mirror image, are formed in a substrate molecule and which produces the stereoisomeric products in unequal amounts are formed in a substrate molecule and produces the stereoisomeric products in unequal amounts. Also, all the stereogenic quaternary carbon centers were enhanced by the desymmetrization of 2-substituted glycerols using a chiral imine/CuCl catalyst, otherwise known as copper (I) chloride.

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     Synthesis of antibiotics such as erythromycin and azithromycin shows how the chemical structure and formula can be modified in order to change its function and its effect on the body accordingly. Although erythromycin was created first, scientists and doctors were able to enhance its molecular formula in order to enhance the process and activity in which it deals with an infected area. Also, these synthetic drugs offset and affect series of reactions such as hydrolysis, which can either interfere or not affect other processes. Overall, the synthesis of such antibiotics require much difficulty due to the fact that many factors such as the complexity of the compound or different incorporated ingredients that change the orientation of each function and process.