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58 Cards in this Set
- Front
- Back
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Define Green Chemistry |
avoiding the creation of waste or pollution in appose to 'cleaning' it up |
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List 6 of the 12 Principles |
prevention, atom economy, use of renewable feed stock, catalysis, accident prevention, reduce derivatives |
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Name 4 atom economic reactions |
Addition, Rearrangement, Diels-Alder, Concerted reactions |
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Name 4 un-economic reactions |
Elimination, Substitution, Wittig, Grignard |
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Equation for Atom economy |
100 x (mr of desired product/ mr of all reactants) |
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Define carbon efficiency |
measure of the amount of carbon in product compared with reactants |
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Equation for E-factor |
Total mass of waste/total mass of product, determined from process not theory |
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What process minimises waste for sodium carbonate production |
Solvay process > Leblanc |
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Define risk |
the probability that harm will occur (hazard x exposure) |
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Whats best to use in the pulp and paper industry and why |
H2O2 is better than chlorine based oxidants as no chlorinated organic by-products just water |
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Name a useful intermediate for making fragrances, agrochemicals and pharmaceuticals |
Cinnamyl alcohol - selectivity of oxidant |
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What must be considered when assessing energy source |
influence on selectivity and yield |
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Name 3 alternative energy sources |
Photocataylsis, ultrasound and microwaves |
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How does photocatalysis work |
uses light as an energy source and is introduced in form of an excited state. low cost from sunlight |
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Explain ultrasound as a form of energy source |
sound transmitted as a wave with alternating cycles, the waves arent directly absorbed by molecules. Low pressure can overcome IMF's of binding fluid and energy released |
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What molecules absorbed microwaves |
selective polar molecules - give heating of up to 100 degrees |
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Define selectivity |
amount of substance converted to desire product as a percentage of total consumed substrate |
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Define turnover frequency |
number of moles of product produced per mol of catalyst per s
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Define turnover number |
amount of product per mol of catalyst |
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Main difference between heterogeneous and homogeneous catalyst |
heterogeneous - disting solid phase medium with slower rates and lower selectivity homogeneous - same phase as reaction with higher rates and selectivity |
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Advantages of phase-transfer catalysts |
higher productivity, higher selectivity, easier to separate products and results in less use of hazardous solvents |
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Advantages of biocatalysys |
faster throughput, high selectivity, non-toxic |
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Society conflict with legislation |
Work dorce needs protecting Imposition of regulator Self regulating doesnt work Public confidence lost |
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industrial conflict with legislation |
Waste minimising approach reduced more High cost so high env. risk elsewhere Env. costs equal high retail prices Legislation difficult to enforce |
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What does REACH stand for |
registration, evaluation, authorisation of chemicals |
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Explain Dossier evaluation |
agency scrutinises testing proposals submitted with a registration dossier |
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Explain substance evaluation |
members state an annual list of potential dangerous substances that need in depth analysis |
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What is one of the biggest problems with REACH |
they have very high costings so small business are being put out of business, promoting competition, SIEF put in place but at a high cost still |
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Why are Pourbaix diagrams used |
species of a given element has different environmental effects and toxicity |
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What does the E value indicate, if positive? |
how oxidising/reducing a system is by measuring availability of electrons, if positive then less electrons so high oxidation state |
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Where do the following lie on the diagram: high OS, low OS, negative charged and positive charged species |
high OS = top low OS = bottom negative charged = RHS positive charged = LHS |
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which lines are responsible for precipitation and redox equilibria |
precipitation = vertical redox = horizontal |
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what happens as the pH decreases in a system |
OH- concentration decreases, equilibrium lies to the side where OH- is |
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Explain what happens for: species a < 0.83 = Eo = 1.23 > species b |
species a, if reducing agent, will be oxidised species b, if oxidising agent, will be reduced |
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Give the Nernst Equation |
E = Eo - 2.303RT /nF . log10[red]/[ox] |
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as pH increases and E increase what will the dotted line gradient be |
positve, if E decreased = negative |
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Explain waste prevention and atom economy as principles |
Prevention - better way to go about rather than cleaning up Atom ec - synthetic methods developed to maximise incorporation of all materials |
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Explain waste prevention and atom economy as principles |
Prevention - better way to go about rather than cleaning up Atom ec - synthetic methods developed to maximise incorporation of all materials |
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Explain reduced derivatives |
Steps requiring additional reagents and generate more waste are to be avoided |
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How should a catalyst be selected |
Selective catalysts prioritised over stop chimeric products |
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How should a catalyst be selected |
Selective catalysts prioritised over stop chimeric products |
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What are the waste products in the Le blanc process |
HCl, CaS and CO |
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Expand on silenafil citrate |
New greener rate developed and commercially used, doesn't involve any protonation or deprotonation so less waste generated |
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Expand on silenafil citrate |
New greener rate developed and commercially used, doesn't involve any protonation or deprotonation so less waste generated |
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What replace tin chlorine reduction in sildenafil citrate |
Catalytic hydrogenation |
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Expand on silenafil citrate |
New greener rate developed and commercially used, doesn't involve any protonation or deprotonation so less waste generated |
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What replace tin chlorine reduction in sildenafil citrate |
Catalytic hydrogenation |
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What are the advantages of ultrasound as a form of energy source |
Rate and yield improvements, free radicals remains unaffected and mechanical effects can improve heterogeneous reactions |
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Expand on silenafil citrate |
New greener rate developed and commercially used, doesn't involve any protonation or deprotonation so less waste generated |
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What replace tin chlorine reduction in sildenafil citrate |
Catalytic hydrogenation |
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What are the advantages of ultrasound as a form of energy source |
Rate and yield improvements, free radicals remains unaffected and mechanical effects can improve heterogeneous reactions |
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Advantages of microwaves |
Reactions can be carried out in polar solvents and in solid state |
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What do anions with large gyration energies have a higher affinity for |
Aqeous phase |
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What do anions with large gyration energies have a higher affinity for |
Aqeous phase |
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Give the equations for phase transfer catalyst |
- |
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Why should we take an environmentally friendly approach |
System based approach is required Industry need to self govern carbon footprint limits set on potential pollutant concentrations in waste solution Graduated taxes on specific products |
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Give the REACH process |
- |
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What do redox and ppt equilibria depend on |
Temp, pH and new environment parameter |
