Chemistry, Chemistry everywhere

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[ucresearch]

Chemists fabricate novel rewritable paper

According to some surveys, 90 percent of all information in businesses today is retained on paper, even though the bulk of this printed paper is discarded after just one use.

First developed in China in about the year A.D. 150, paper has many uses, the most common being for writing and printing upon. Indeed, the development and spread of civilization owe much to paper’s use as writing material.

Such waste of paper (and ink cartridges) — not to mention the accompanying environmental problems such as deforestation and chemical pollution to air, water and land — could be curtailed if the paper were “rewritable,” that is, capable of being written on and erased multiple times.

Chemists at the University of California, Riverside have now fabricated in the lab just such a rewritable paper, one that is based on the color switching property of commercial chemicals called redox dyes. The dye forms the imaging layer of the paper.  Printing is achieved by using ultraviolet light to photobleach the dye, except the portions that constitute the text on the paper.  The new rewritable paper can be erased and written on more than 20 times with no significant loss in contrast or resolution.

Read more about it here →

[hydrogeneportfolio]

Six Women Who Changed Science. And The World. Part 2.

Part 1 • Purchase

[thecraftychemist]

Fuming Nitric Acid Reacts with Nitrile Gloves

Fuming nitric acid is what you get when the concentration of nitric acid is greater than 70%. Red fuming nitric acid is an extremely strong oxidizer and reacts readily in contact with organic compounds like acetone. In addition, its vapor is corrosive and causes severe burns. As a main component in certain types of rocket fuel, it has a tendency of producing very exothermic reactions. When it comes in contact with nitrile gloves, for instance, it sets them on fire, as you can see in the GIF.

Image credit: Nile Red via Youtube

I’ve only ever worked with concentrated nitric acid or less and we were using nitrile gloves. Apparently the chemist in this video is wearing butyl rubber gloves.

Never settle for whatever is convenient. If you have doubts about your PPE consult a guide. Full glove guide including links to manufacturer charts relating to specific chemicals can be found here.

EDIT: Reblogging because I just discovered the GIF wasn’t working.

Video source

[itscolossal]

Beautiful Chemistry: Amazing Chemical Reactions Filmed with a 4K UltraHD Camera [VIDEO]

[sleepismyenemy-blog1]

Sue’s face though

[labphoto]

Formylation (aldehyde group insertion to the molecule) with the Vilsmeier–Haack reagent. 

This pretty useful reaction is named after Anton Vilsmeier and Albrecht Haack who discovered, that if phosphorous-oxychloride is added to a substituted amide (they used originally N-Methylformanilide, but N,N-dimethylformamide works also great) a chloroiminium ion will form. If an activated aromatic compound is present, an electrophilic aromatic substitution produces an iminium ion intermediate, which can be hydrolyzed to give an aryl aldehyde. This happens: 

-image from wikipedia.

The reaction depending on the temperature control and a few other things, could also produce a few side products. The “gunk”, what is produced from the side reactions could easily result an intense, adorable colored reaction mixture, just as seen on my favorite picture: http://labphoto.tumblr.com/post/85408986808/the-blood-red-reaction-product-is-poured-on

[psicologicamenteblog]

Source: Chemical structures of neurotransmitters.

Follow Francesca Mura on Pinterest

[ri-science]

Why you should never put water on an oil fire.

On the roof of the Royal Institution, Dr Peter Wothers (presenter of the 2012 CHRISTMAS LECTURES) pours a small amount of water into a beaker of oil. The reaction is so violent because water and oil don’t mix. When the water is poured into the beaker of burning oil it sinks to the bottom and, due to the intense heat, vaporizes into steam almost instantaneously. With this phase change from a liquid to a gaseous state the water expands by up to 1700 times and forces the fire above it upwards. This oxygenates the oil and creates the huge flame.

Watch the full video, with more explanation, here.

[yesindeedchemistry]

Oil Dispersants

Oil spills are a very unfortunate reality of our world. Tankers filled with oil become damaged by rocks or become beached and eject their contents into the marine environment causing a lot of damage to local fauna and flora.

Due to the cohesive nature of oil it can be very hard to remove quickly. Microbial life and turbulence can break up the oil over time but because the oil stays together and gives the microbes a very small surface area to work with and movements in the ocean are not enough. it takes a very long time to break up the oil naturally. 

This is yet another job surfactants are employed into, oil dispersants which also contain solvents to dissolve the emulsifiers as many are solid at room temperature. The addition of surfactants breaks up the oil layer into smaller  droplets that have much larger surface area for microbes to begin decomposing the oil and ocean turbulence can also break the oil down much quicker.

There are some toxicity effects related to the dispersants however but they are used in a case by case circumstance depending on the dangers posed by the oil spill such as. Oil will have no effect to coral systems if they are subtidal. If a mangrove system is threatened they will be considered. This issue however is complicated if a coral system is close to a mangrove system because the oil droplets will be deposited into the water column which will have adverse effects on coral.

As such considerations are taking into account before they are used to protect a habitat currently effected by oil:

Expected sensitivity of exposed resource

Proportion of the resource that would be affected 

Recovery rates of the exposed resource

Oil dispersants are thus only used when the benefits of breaking down the oil outweigh the effects they will have on the environment. If they will benefit the majority of the habitat with possible damage to a couple of species they will be used because the habitat is conserved as a whole

[labphoto]

Distilling an organosulfur compound. 

We hoped that after the distillation a relatively pure compound will be the result, but sadly at least two component is present in the receiving flask. The only good point is, that it’s not a mercaptan, so it does not have an awful odor.

[yesindeedchemistry]

Enhanced Oil Recovery

As a race we will rely on oil resources well into the near future due to alternatives like solar energy still being cost inefficient (costing a lot to install and having to be replaced regularly to generate energy). Unfortunately our oil reserves are running out quickly and within 50 years our current oil reserves will be gone.

At least that is what they tell you. In actuality the vast majority of mature oil fields still contain approximately 50% of the oil that they contained when they were discovered. The reason for this is the great pressures maintained in underground oil reserves.

Currently there  are two operations that take place in Oil Recovery:

Primary - An oil field is discovered and drilling operations take place, this is where the traditional image of oil spurting out of the ground comes from, the pressure is so great underground that the oil is forced out of the hole to equalise the pressure. Approximately 25% of the oil is claimed in this way.

Secondary - Once the pressure has equalised the oil will no longer exist the hole under its own steam. At this point a second hole is bored into the ground to allow seawater to be pumped into the oil reservoir. The additional pressure underground forces around another 20% out of the ground before the pressure once again equalises and no more can be drawn out of the ground.

At this point all of the "free" oil has been removed but approximately 50% of the oil is still trapped within the pores of rocks. The capillary pressure being far too high to remove easily.

Research is being done into the use of surfactants as they lower the interfacial tension (IFT) between the water and the oil to "ultralow" values of approximately 0.001 N/m. This lowering of IFT also effects the contact angle observed between the three phases of oil, water and rock, known officially as the water/oil/rock three phase contact angle. 

The contact angle depends upon how the liquid and the surface interact. If the surface is hydrophobic such as in the pore of an oil field rock the angle is obtuse, over 90 °, 

In the lab, without the presence of surfactants this three phase contact angle is measured to be above 90 ° which indicates that the rock is hydrophobic and hence the water cannot penetrate into the pore to remove the rock, the water will not spread however, when the surfactants are added the observed three phase contact angle is significantly reduced to values of around 46 °, the rock becomes more hydrophilic and oil begins to leave the pores of the rock. Unfortunately at the moment the best results  of oil recovery that have been obtained in the lab are less than 50% and oil fields each have different types of rock within them based on their geographical location which suggests that a special blend of surfactants may be required for each oil field as different surfactants such as CTAB (Centrimonium Bromide) and SDS (Sodium Dodecyl Sulphate) show different results for their relative amounts of oil recovered.

This research is important for the surfactant industry when you realise that surfactants are made from derivatives of crude oil and the price of surfactants only goes up everyday as oil becomes more and more scarce.

It should be noted that crude oil is unique depending on where it comes from as well with different amounts of certain alkanes so special blends for each oilfield site may need to be made.

Glossary

Mature Oil Field: a field that has seen its peak production in the past and is now in a state of declining productivity.

[yesindeedchemistry]

Surfactants: Your household friend

So in the liquid crystal post I mentioned that the University of Hull became famous for its work in that field of research though it is still true the Surfactant and Colloids research group is probably the main reason the department is one of the few that is self funded on campus as these substances are immensely important both industrially and commercially.

Your kitchen and bathroom are filled with surfactants thanks to their ability to remove grease and oils from surfaces. The name comes from their full title SURFace ACTive ageNTS. For the rest of this post I will call surfaces interfaces just because I like to use the term please bear in mind they are equivalent.

So what is a surfactant?

These compounds are unique because they have a hydrophilic head group and well as a hydrophobic alkyl tail or tails. They are synthesised from crude oil industrially with examples such as anionic Sodium Lauryl Sulphate and Centrimonium Bromide which is cationic due to the presence of the sodium and bromide which leave upon dissolution in water.

Chemical structure of Centrimonium Bromide, known as CTAB for short. For surfactants to be affective they have very long alkyl chains. The effective size of the head group can be supplemented by their electric charge.

Surfactant monomers show the interesting property of being able to alter interfacial tensions, the greater the concentration of monomers the lower the tension will become. Monomers will line up on the surface of water with the tails standing out into the air if no oil phase is present. Interfacial tension is responsible for why water and oil do not mix so by lowering the difference between them you can cause them to mix.

Surfactants are also unique because they form Micelles over a specific concentration for each surfactant species. When micelles begin to form the the interfacial tension will not decrease any further and this is a very good measure of the Critical Micelle Concentration or cmc, the point above which micelles are allowed to form.

Micelles are usually spherical and come in two forms

Normal - micelles formed in water the alkyl tails form up inside the cores of the micelles with the head groups making up their surfaces and comprise of between 60 and 200 individual surfactant molecules.

Reverse - these form in oily phases and the head groups make up the cores with the alkyl chains making up the outer layer. These are harder to make and are made up of only 20 or so molecules.

Cross-sectional diagrams of normal and reverse micelles. There are images that show each head being dissociated with its counter-ion but this would mean micelles had a charge of -/+ 60 which is not the case. Micelles are usually around 20-30% dissociated.

These properties make surfactants very good as cleaning products and when you are doing the washing up the oily grease can be removed much easier. Oil in water microemulsions are formed in your sink. Different surfactants are used depending on the application. For "wet" cleaning you will use surfactant mixtures that promote positive curvature and form oil in water microemulsions whereas for "dry" cleaning you use surfactant mixtures that show negative curvature which form water in oil emulsions. The curvature of the surfactant layers can be effected with variables such as changing the concentration of salt in the mixture as this screens the electrostatic charges of the head groups and causes them to shrink which will make the curvature more negative. A curvature of zero will form a flat layer which will create a bicontinuous microemulsion where one phase is not suspended within the other but they are suspended within each other.

There are three types of microemulsions. Oil in water microemulsions are known as Winsor I and show positive curvature. Winsor II is the opposite and form water in oil microemulsions with negative curvature. Bicontinuous microemulsions have zero curvature and but confusinglly are called Winsor III 

Glossary

Hydrophilic: the functional group prefers to be suspended within a water (aqueous) medium

Hydrophobic: prefers to be suspended within an oily phase and will do so if one is also present

[compoundchem]

[thecraftychemist]

compoundchem:

An update to the previous graphic on organic functional groups today, with some additions and refinements to make it a little clearer.

As always, you can download the PDF on the site: http://wp.me/p4aPLT-3c

[yesindeedchemistry]

Liquid Crystals 101

So we go to the University of Hull, our Chemistry Department became famous arguably around the world thanks to Prof. George W Gray (1926 - 2013). He is credited with major developments in Liquid Crystals for consumer use, a product with which the modern world would not exist as we know it. Though Hull is not the birthplace of liquid crystals it was made viable as a room temperature display in the department. This fourth state of matter has been known about since 1888 and was discovered by Friedrich Reinitzer in Germany

George Gray with a sample of Liquid Crystals

For those that don't know you're looking at this text post through a liquid crystals display (LCD), almost every modern electronic display contains a thin layer of liquid crystals and have done since the 60s.

As the name suggests these substances are part way between a solid phase and a liquid phase and as such show a combination of the properties seen in both phases individually i.e. they will flow like a liquid and due to their solid nature they scatter light much like a colloid does. Because they are not isotropic liquids they also show an interesting property called birefringence where the refractive index of the length of a crystal is not the same as the refractive index of the width of a crystal so as light scatters within the structure it splits into two oppositely polarised streams which have their own unique velocity..

This is a collection of liquid crystal molecules, as you can see they are long and thin hence light that passes through the width passes through less matter and as such is refracted much less than going through the height of a molecule. The image also shows why the properties cannot be isotropic, if this was the case the molecules would be sphere shaped however they are rod shaped.

There is an issue with liquid crystals however, they only exhibit the liquid crystal phases within a small temperature range and up until the 60s this range was too hot to be sustainable as an imaging technology. There are two distinct LC phases; nematic and smectic

Nematic: the molecules are all aligned in the same direction but they are free to move randomly much like a liquid. The alignment of the molecules is controlled with an electric current as they are polar

Smectic: molecules are arranged in layers, there is short range order within the layers and they can slip over one another much like graphite layers will.

This is the order the phases are observed as the temperature is changed, it can be seen from this gradient then that the smectic phase behaves more like a solid and a nematic phase behaves more like a liquid

The first commercially available liquid crystals were available in the 70s and digital calculators were born they were very basic by todays standard but it was an incredible breakthrough at the time as nematic phases were present at room temperature which had taken a lot of research and development. 

An LCD in action, light enters the liquid crystal nematic phase in one end of the display through a polariser which limits the amount of light entering the display. An electric current then causes the crystals to twist and polarise the in a certain direction depending on what you wish to display. the light then meets a second polariser which either allows the polarised light through or it is blocked and appears dark which is how the numbers on a calculator are displayed.

Liquid Crystals allowed technology to move away from the cathode ray tube which were big and clunky and what replaced them was ultimately thinner and lighter. Improvements in technology almost always result in the downsizing of instruments and the Modern Western World could not exist without this special class of molecules.

Glossary

Colloid: a mixture of two phases where one phase is dispersed within the other phase, examples of this are milk (particles of fat with a layer of proteins suspended within a water medium)

isotropic: the properties of the substance are equivalent in the x,y and z directions within the structure

[4ragon]

I bet before Carlos moved to Night Vale he used to regularly reinvent really useless household appliances all the time.

Like ‘Hey check this out it looks like a regular umbrella but it’s also COMPLETELY FIREPROOF’

and everyone would be like ‘Carlos why the hell would anyone NEED a fireproof umbrella if it’s already raining seriously stick to science’

but in Night Vale everyones like ‘Aw man this is PERFECT for when it starts raining fire/gasoline/literal death’ and Carlos is just like ‘My time has come’

[cenchempics]

VIBRANT A flask contains monoacetyl ferrocene prepared by George Osbourn in an undergraduate chemistry lab at the University of Sheffield.

Credit: George Osbourn

[cenchempics]

HEATED

In this solution of a manganese complex with a nitrogen-sulfur mixed-donor ligand, solvent is being removed under a reduced pressure in a vacuum flask to spur crystallization and increase the concentration of the product. This new complex could be used as a catalyst to convert carbon dioxide to methanol,which can be used as an industrial solvent.

Credit:  Submitted by Casey Oian Enter our photo contest here