Discuss the need for ALTERNATE SOURCES of compounds presently obtained from the petro-chemistry industry.

The presently obtained compound for the petrochemistry industry for making polymers is crude oil. Being a non-renewable source, there is concern that human activity has the potential to completely exhaust reserves of fossil fuel resources within the century. There is major pressure to develop alternate fuels:

Greenhouse problem Higher cost as supply diminishes Less than 5% of fossil fuel is used to make plastics and only a small percentage of that plastic

is recycledFor these reason, there is a need for an alternate resource to replace out petrochemical derived compounds, to find alternate sources of ethylene and propene.

There is however an even more tantalising source for starting materials for making many of the polymers that are so useful today, and that is cellulose. Cellulose is a major component of plant material, whereas starch and sugars are minor components. In order to explore the possible use of cellulose for making petrochemicals, we need to look at the general structure of natural polymers (starch, cellulose, proteins). This leads us to what are calledCondensation polymers.

Explain what is meant by a CONDENSATION POLYMER Condensation polymers are polymers that form by the elimination of a small molecule (often water) when pairs of monomer molecules join together. A condensation reaction eliminates a small molecule, thus condensation polymers do not have all the atoms initially present in the monomers, therefore are different to addition polymers.

Monomers for condensation polymerisation MUST have two functional groups (e.g., amine and carboxylic acid chloride)The most common synthetic condensation polymers have amide linkages, i.e nylon, and ester linkage i.e. polyester other examples: nylon-66, proteins from amino acids

Describe the reaction involved when a condensation polymer is formed.

The reaction involved when a condensation polymer is formed is the linking of two monomers and the emitting of one small molecule, usually water. Monomers with only one reactive group terminate a growing chain, and thus give end products with a lower molecular weight. Linear polymers are created using monomers with two reactive end groups and monomers with more than two end groups give three dimensional polymers which are cross linked.

For example, a condensation polymer is formed when monomers such as beta glucose polymerize together through the reaction between the OH (hydroxyl) groups. The OH groups in 2 glucose molecules break and eliminate an H-OH (water) molecule; the remaining -O- (oxygen) group links the monomers forming a long chain.

Andr

ew H

an C

hem

istr

y Re

sear

ch T

ask

1

Describe the structure of CELLULOSE and identify it is an example of condensation polymer, found as a major component of biomass.Cellulose is the most abundant molecule in living tissue, being a major component of plants, being the basic structural component of cell walls, making approximately 50% of total organic carbon in the biosphere. Thus, cellulose is found as a major component of biomass.

Cellulose is a naturally occurring condensation polymer, the monomer which it forms being glucose.i.e.Glucose: HO-C6H10O4-OH, in the HO-OH group, water is eliminated leaving the O- to bond onto the next glucose monomer, in order to form cellulose.

Alternatively we can write this as:n (HO-C6H10O4-OH) → H-(O-C6H10O4) n-OH + (n – 1) H2O

Note: each intersection on the ring has a CGlucose Cellulose

This is saying that n molecules of glucose combine to form one molecule of cellulose (which contains n glucose units) by eliminating (n – 1) molecules of water.

Many of the hydroxy groups form hydrogen bonds that hold the cellulose chains together.

N.B.(OH)- hydroxyl group

a- glucose have hydroxyl groups pointing downward, monomers form starchb- glucose have one up and one down, monomers form cellulose.

Identify that Cellulose contains the basic carbon-chain structures needed to build petrochemicals and discuss its potential as a raw material.

Andr

ew H

an C

hem

istr

y Re

sear

ch T

ask

2

Each glucose unit of cellulose has six carbon atoms joined together in a chain. A three carbon-chain and a four carbon-chain are present within the structure of a glucose monomer in a cellulose chain. These carbon-chains have attached hydrogen and hydroxy groups. These basic carbon-chain structures can be changed to be a raw material for production of petrochemicalsThe carbon-chain sections could be changed to chemicals that, at present, are mostly made from petroleum. If a chemical process can be developed or a micro-organism found that can break the glucose into three carbon-chains and four carbon-chains this would be very useful since many polymers are made using three carbon monomers (such as polypropylene in Australian 'paper' currency) or four carbon monomers (such as those used to make synthetic rubbers). Thus biomass, a renewable resource, could be used instead of fossil fuel, a non-renewable resource, to make polymers (like in money and tyres!)

Cellulose can be manipulated to produce ethylene and polymers. Ethanol is the prime candidate for an alternative source of ethylene. Ethanol can be produced by fermentation of starch and sugars from a variety of agricultural crops and it can be easily converted to ethylene.

Ie.(Decomposition) (Fermentation)(Dehydration) (Addition) (Polymerization)

Cellulose Glucose ethanol Ethylene monomers polymers

Cellulose is biodegradable, meaning it will not affect the environment in its use as a raw material in the Petrochemical industry. Because it is a renewable resource, it further increases its potential to be used in the petrochemical industry, being a source of alkenes to manufacture polymers, However, it is difficult to convert Cellulose into glucose efficiently on a large scale, hence the ethanol and ethylene is difficult to obtain, and because vegetation must be grown in order for the extraction of cellulose, vast areas of land are required, which could result on negative environmental impacts, such as deforestation, resulting in land erosion, land degradation and salinity. Therefore, there is a HIGH potential for cellulose to create ethylene, which can benefit the petrochemical industry and the environment, which can be further manipulated to create polymers, restrictive technology does not allow us to efficiently convert the cellulose into glucose, and hence cellulose will not replace petrochemicals.Use available evidence to gather and present data from secondary sources and analyse

progress in the recent development and use of a named BIOPOLYMER . This analysis

Andr

ew H

an C

hem

istr

y Re

sear

ch T

ask

3

should name the specific enzyme(s) used or organism used to synthesise the material and an evaluation of the use or potential use of the polymer produced related to its properties

Introduction: Biopolymers are naturally occurring polymers, generated via natural means. I.e. using natural resources like plants and micro organisms. One example of a biopolymer is polyhydroxybutyrate (PHB)

How Biopolymer is produced: PHB was first produced in 1925 in a lab when a certain type of micro-organism named Alcaligenes Eutrophus was fed a particular nutrient, which allowed this bacteria to multiply into large colonies. By restricting the nutrient, the bacterium was unable to reproduce and so instead, it stored its contained nutrients in the form of PHB. The bacterium was then harvested and PHB extracted. OR MORE SIMPLY, it is produced by certain bacteria processing glucose or starch. Through time, scientists have discovered improved techniques in extracting PHB. By genetically modifying crops such as corn with the PHB gene, a greater amount of the polymer was able to be extracted. Properties of Biopolymer: PHB is used in a variety of ways due to its useful properties- it is completely biodegradable, renewable and non toxic, water insoluble, biocompatible (suitable for medical use) etc. Potential use of Biopolymer: Some of its uses include disposable nappies, bottles, packages and containers.Since PHB is a renewable resource and possess useful properties, it has high potential of being used for a variety of purposes, even in the medical field (such as internal medical sutures). It is non toxic and biodegradable, so it does not have to be removed after recovery. While PHB wouldn’t be economic for plastics that should be non-biodegradable, such as for piping, it would be potentially successful in the use of plastic bags and containers since it is environmentally friendly.

Judgment/Conclusion: PHB has high potential for abundant use in the future if a commercially viable method of production is found, while still maintaining its useful properties in the compound.

Describe and account for the many uses of ETHANOL AS A SOLVENT FOR POLAR AND NON-POLAR substances Ethanol is the second most important solvent due to its effective dissolving properties. It is used in cleaning agents, antiseptics, medicines, perfumes and other chemicals.

Ethanol is a good solvent because it has a OH (hydroxyl) group. The large electro negativity between the hydrogen atom and the oxygen atom creates polarity in the molecule; therefore, it can attract other polar molecules and dissolve them, often forming a strong hydrogen bond with other polar molecules, this attraction dissolving the polar substances.

Ethanol also can dissolve non-polar substances such as oil since it has a non polar ethyl (c2h5) group. This group experiences dispersion forces, and since other non-polar

Andr

ew H

an C

hem

istr

y Re

sear

ch T

ask

4

substances posses dispersion forces, the interaction between the molecules allow dissolving to occur, displayed by the rule “likes dissolve likes.”

Describe and account for the many uses of ethanol as a fuel and explain why it can be called a renewable resource.Ethanol is blended into car petrols and used to fuel cars. It is used as a solvent in dissolving medicines and food flavourings and colourings that do not dissolve easily in water. Once the non-polar material is dissolved in the ethanol, water can be added to prepare a solution that is mostly water.Ethanol is considered a renewable resource because it can be obtained from the decomposition of cellulose, found in plant material, which is a renewable source. Furthermore, when it undergoes combustion, it forms carbon dioxide (CO2) and water (H2O) C2 H5 OH( l) + 3(O2) g 2(CO2) g + 3H2O( l)Water is a naturally occurring liquid and carbon dioxide a naturally occurring gas, it being absorbed by plants in photosynthesis and returning back into the Carbon cycle. Since ethanol is obtained from nature and returned back into nature to be “recycled” to form new plant material and thus more ethanol, it is considered a renewable source.

Assess the potential of ETHANOL AS AN ALTERNATIVE FUEL and discuss the advantages and disadvantages of its use

Presently, the potential of ethanol to be used as an alternative fuel is unlikely. Methods which produce ethanol are too expensive compared to obtaining petrochemicals from non renewable crude oil. However, as fossil fuel supplies dwindle, and it becomes more expensive/ taxes are imposed on their use, or if a cheaper way to extract ethanol from biological sources is found, then ethanol indeed has a high potential of becoming a fuel substitute.

Advantages: Ethanol can be produced by two methods. The common method is by additionally reacting water with ethylene.

dilute H2 SO4+ heat C2H4+ H2 O C2 H5OH

The main advantage of ethanol as a fuel produced this way is that it produces a much cleaner burn when combusted, and so does not pose a significant threat to the environment, as petrol.

However, compared to petrol, producing ethanol through this method required greater amounts of energy, hence is more costly. Furthermore, the ethanol produced is less efficient than petrol since it does not produce as much energy per gram when combusted.

The second method of producing ethanol is through the fermentation of glucose. Ethanol obtained this way is seen as a more “greener” fuel. An

drew

Han

Che

mis

try

Rese

arch

Tas

k

5

C6 H12 O6 aq 2C2 H5 OH l + 2CO2 g

The production of ethanol through this method does not use any non-renewable sources, therefore our concerns and dependence on our diminishing fossil fuel supplies may be reduced. Moreover, the burning of ethanol is environmentally friendly, since the emitted CO2 returns back to the carbon cycle in nature, by being absorbed by plants for photosynthesis.

Disadvantages: On the other hand, growing sugar cane to obtain glucose for fermentation requires vast areas of land. Therefore, large areas of the natural environment must be cleared, giving rise to deforestation (also resulting in the loss of animal habitat), land degradation, salinity, erosion and other devastating environmental impacts. In addition, the energy and financial requirements are great. The production of ethanol through mass production of plants is much greater than the energy for which it provides. Energy inputs (which are greenhouse unfriendly) for mechanical planting, harvesting and more importantly the energy required to distill the ethanol from the fermented mixture is very high. The resulting wastes from large fermentation plants are extensive and difficult to dispose. Conclusion: Our current technology for producing ethanol through non-renewable resources is inefficient. If an economical and commercially viable method of converting cellulose to ethanol is found, ethanol has a high potential as an alternative fuel but in the mean time, the disadvantages of using ethanol as a direct substitute for petrol far outweigh the advantages. Additional information:

Advantages of using ethanol as a FUEL ALTERNATIVE: Ethanol produces high quality, low cost octane. It combusts more fully, boosting

octane rating in petrol. Ethanol has lower ignition temperatures therefore allows combustion at lower

temperatures It is a renewable resource Reduces our dependence on non-renewable fossil fuels Reduction of greenhouse gases since there are more complete combustions

creating carbon dioxide as products instead of carbon monoxide, which is a greenhouse gas, therefore cleaner air

Less toxic than gasoline and does not pose a severe threat to the environment if in an event of a spill

Works as a solvent to clean engine Since ethanol is a polar and non polar solvent, it dissolves gummy deposits on

engines, cleaning it Ethanol is much more safe than petrol since it has a higher flash point

Andr

ew H

an C

hem

istr

y Re

sear

ch T

ask

6

Disadvantages of ethanol as a fuel alternative: Petrol engines are designed for octane not ethanol therefore damages engine, so

therefore need modification (In Australia there is concern about the sale of 20%ethanol-80%petrol mixtures as petrol. The federal government is planning to restrict petrol to contain no more than 10% ethanol.)

Ethanol causes corrosion of fuel lines, in car engines since it is a polar molecule and water molecules attach onto it entering into car systems

Large areas of land are required for production of ethanol Land is cleared for sugar farms therefore more environmental problems such as

salinity, erosion and deforestation The energy requirements for the production of ethanol through mass production of

plants and distillation are greater than the energy which it provides. High costs for distilling ethanol Large waste products are formed from fermentation since only 15% of ethanol is

produced. The disposal of this waste is another problem.

Process information from secondary sources to summarise the use of ethanol as an alternative car fuel, evaluating the success of current usage

There are many countries around the world who have adapted to the use of ethanol as an alternative car fuel. It boosts octane performance and adds oxygen to the petrol, lowering toxic carbon monoxide emissions.

Countries like Brazil, which experience high pollution levels, have been quick to adopt ethanol as a substitute fuel and reports have proved to be efficient. Brazil has the largest and most successful bio-fuel programs in the world, involving production of ethanol fuel from sugarcane, and it is considered to have the world's first sustainable biofuels economy, by 2008, Brazilian ethanol provided more than 50% of fuel consumption on the gasoline market. Since 1977 the government made mandatory to blend 20% of ethanol with gasoline requiring just a minor adjustment on regular gasoline motors. Today the mandatory blend is allowed to vary nationwide between 20% to 25% ethanol (E25) and it is used by all regular gasoline vehicles and flexible-fuel vehicles(vehicles made to run on purely ehanol-E100). As of May 2009, more than 88% of new vehicles sold in Brazil are flex fuel. Meanwhile, countries such as USA and Canada only blend up to 10-12% of ethanol in their petrol and gases. Other countries such as Australia have been slow in adopt the use of ethanol as an alternative car fuel since it is not cost effective at the present time. Legislation in Australia imposes a 10% cap on the concentration of fuel ethanol blends. Blends of 90% unleaded petrol and 10% fuel ethanol are commonly referred to as E10. Furthermore, the cost of modification of engines to suit ethanol as a fuel is too great.

Judgment: Unless a cost effective method of converting cellulose to ethanol is discovered, ethanol will not be used as an alternative fuel but rather an extensionHowever, it is currently uneconomical to use ethanol as a car fuel, as it is extremely expensive to produce it; especially in the distillation processes.

BIBLIOGRAPHY

Andr

ew H

an C

hem

istr

y Re

sear

ch T

ask

7

WEBSITESIdentification and production of materials, updated ???, visited on the 1/12/10, UNSWhttp://www.chem.unsw.edu.au/highschool/files/materials.pdf

HSC online, updates 2010, visited on the 1/12/10, Charles Stuart Universityhttp://www.hsc.csu.edu.au/chemistry/core/identification/chem922/chem922net.html#sylla1

Condensation Polymerization, updated???, visited 4/12/2010, Materials World Modulehttp://www.molecular-plant-biotechnology.info/transgenic-plants-II/polyhydroxybutyrate-biodegradable-plastic-substrate.htm

Condensation Polymerization and cellulose, updated???, visited 4/12/2010, Materials World Modulehttp://www.materialsworldmodules.org/resources/polimarization/4-condensation.html

The ethanol Alternative, updates 12/10/2006, visited 4/12/2010, ABC televisionhttp://www.abc.net.au/catalyst/stories/s1763365.htm

Petrochemicals, undated???, visited 4/12/2010, Stage 6 Chemistry Teaching and Assessment Resourcehttp://www.scu.edu.au/schools/edu/ICT/student_pages/sem2_2005/SAllery/act1.html

Sugarcane ethanol: Brazils Biofuel success, updated 2010, visited 4/12/2010, Science and development Networkhttp://www.scidev.net/en/features/sugarcane-ethanol-brazils-biofuel-success.html

Books

Roland Smith, 2006, CONQUERING CHEMISTRY 4th edition. Pages 2-91

Andr

ew H

an C

hem

istr

y Re

sear

ch T

ask

8