Thursday, October 24, 2013

Isobutanol

Isobutanol is an organic compound with the formula (CH3)2CHCH2OH. This colorless, flammable liquid with a characteristic smell is mainly used as a solvent. Its isomers include n-butanol, 2-butanol, and tert-butanol, all of which are important industrially.
Isobutanol is produced by the carbonylation of propylene. Two methods are practiced industrially, hydroformylation is more common and generates a mixture of isobutyraldehydes, which are hydrogenated to the alcohols and then separated. Reppe carbonylation is also practiced.
And isobutanol could indeed function as a relatively effective substitute for gasoline — isobutanol releases just around 82% of the heat energy that gasoline does when burned, as compared to the 67% that ethanol does. And, perhaps more importantly, isobutanol doesn’t possess the same significant drawbacks that ethanol does — in particular, it doesn’t possess ethanol’s unfortunate tendency to absorb water, and thus doesn’t damage conventional engines and pipelines in the same way that pure ethanol does. So, while pure ethanol would only be a viable replacement for gasoline if all of the infrastructure in use today was completely replaced, isobutanol cold simply replace gasoline as is — no new infrastructure needed.
Isobutanol — a high-performance biofuel that closely matches the properties of gasoline — can be produced from waste plant materials through the combined actions of a common fungus and a common bacteria, according to new research from the University of Michigan. When paired up together, the fungus Trichoderma reesei, and the bacteria Escherichia coli, can effectively create the biofuel isobutanol from materials such as cornstalks and plant leaves.
While the production of a useful biofuel is impressive enough, the researchers think that the same principle used to produce the biofuel could be used to produce other useful chemicals, such as plastics.
Isobutanol is also produced naturally during the fermentation of carbohydrates and may also be a byproduct of the decay process of organic matter. The biosynthetic pathway used to produce isobutanol was first discovered in species of bacteria from the genus Clostridium. This pathway has been genetically engineered into several species of microorganisms which are more easily manipulated by current scientific methods than microorganisms of the genus Clostridium.
And isobutanol could indeed function as a relatively effective substitute for gasoline — isobutanol releases just around 82% of the heat energy that gasoline does when burned, as compared to the 67% that ethanol does. And, perhaps more importantly, isobutanol doesn’t possess the same significant drawbacks that ethanol does — in particular, it doesn’t possess ethanol’s unfortunate tendency to absorb water, and thus doesn’t damage conventional engines and pipelines in the same way that pure ethanol does. So, while pure ethanol would only be a viable replacement for gasoline if all of the infrastructure in use today was completely replaced, isobutanol cold simply replace gasoline as is — no new infrastructure needed.
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Friday, October 11, 2013

Have a knowledge of phenol

A phenol is one of a number of chemically active compounds which are found throughout nature, especially in plants. Their molecules each include a hydroxyl functional group (OH) bonded to the ring of an aromatic compound — a molecule that includes at least one ring of carbon atoms. Phenols exhibit a wide range of properties; some are heralded for their health benefits, while others are deadly poisons. Some have important industrial uses as drugs or food additives. The word phenol may also refer to carbolic acid (C6H5OH), the simplest of this group of chemicals.
Phenol is the simplest member of a family of compounds in which an -OH group is attached directly to a benzene ring. Phenol itself is the only one of the family that you are likely to need to know about for UK A level purposes.
There is an interaction between the delocalised electrons in the benzene ring and one of the lone pairs on the oxygen atom. This has an important effect on both the properties of the ring and of the -OH group.
Pure phenol is a white crystalline solid, smelling of disinfectant. It has to be handled with great care because it causes immediate white blistering to the skin. The crystals are often rather wet and discoloured.
Phenol is so inexpensive that it attracts many small-scale uses. It once was widely used as an antiseptic, especially as carbolic soap, from the early 1900s through the 1970s. It is a component of industrial paint strippers used in the aviation industry for the removal of epoxy, polyurethane and other chemically resistant coatings. Phenol derivatives are also used in the preparation of cosmetics including sunscreens, hair colorings, and skin lightening preparations. Concentrated phenol liquids are commonly used in the surgical treatment of ingrown toenails to prevent a section of the toenail from growing back. This process is called phenolization.
When phenol donates a hydrogen ion to water, the electron pair remaining on the oxygen atom becomes delocalized, meaning that it becomes redistributed into the phenyl ring and cannot be assigned with certainty to any one pair of atoms. This effect is possible because of the π bonds in the phenyl ring (bonds that form between overlapping unhybridized p-orbitals). In cyclohexanol, on the other hand, all of the carbons in the ring structure share single bonds and there are no π bonds, so the negative charge on the oxygen does not become delocalized if the hydrogen is donated to water.
In a phenol extraction, the acidity of the whole mixture is important to effectively extract the DNA and RNA. Chemists recommend that the phenol should have a pH higher than 7 so that the water layer can successfully gather the DNA. At a pH of 4.5, which is already considered acidic, the RNA can already be gathered by the water phase. To change the phenol’s acidity or alkalinity, some chemicals are added, such as the compound tris or N-ethylmorpholine.
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