D6

Question 1

Solvent waste

Answer 1

many organic solvents toxic and left over following the synthesis
disposal can involve chemical treatment or in many cases incineration which releases toxins into atmosphere
solvent waste = largest contributor to waste issues facing pharmaceutical companies by mass

Question 2

Solvent suitability

Answer 2

3 categories: toxicity to workers (carcinogenic, direct toxicity), process safety (flammability, explosive, toxic by-products), harm to environment (soil/ground/water contamination, ozone depletion, greenhouse gas formation)

Question 3

Green chemistry

Answer 3

Based on set of principles that when used in the design, development, and implementation of chemical products and processes, enables scientists to protect and benefit the economy, people, and planet
uses renewable, biodegradable materials, uses catalysis and biocatalysis to improve efficiency and conduct reactions at low or ambient temps, reduces the use and generation of hazardous substances

Question 4

Nuclear waste

Answer 4

440 nuclear power plants worldwide - produce 16% of world’s energy
Ad: no air pollution, greenhouse gases, fuel source (uranium) abundant enough to supply energy for 1000 years
Dis: safety concerns, rising costs, public outcry, disposal of waste
Increased use of radioisotopes for treatment and diagnosis means disposal of nuclear waste is growing concern for medical industry

Question 5

High level waste (HLW) definition

Answer 5

wastes that give off large amounts of ionising radiation for a long time

Question 6

Characteristics of HLW

Answer 6

long half-life, high activity, low volume, very hot

Question 7

Sources of HLW

Answer 7

Used nuclear fuels from nuclear reactors, waste products from processing used fuel, nuclear weapons

Question 8

Storage/disposal of HLW

Answer 8

Vitrified (made into glass) and then sealed in steel containers and buried underground in granite rock or in deep mines

Question 9

Issues of HLW

Answer 9

May still leak into water table, remains active for a very long time, geological instability, potential weapon for terrorists

Question 10

Low level waste (LLW) definition

Answer 10

wastes that give off low ionising radiation for a short time

Question 11

Characteristics of LLW

Answer 11

Short half-life, low activity, high volume (around 90%)

Question 12

Sources of LLW

Answer 12

Materials such as gloves, coats, paper, tools, towels, syringes, injection needles - become radioactive from exposure to radiation e.g. sterilising equipment in hospitals, manufacture of smoke detectors, irradiating of food, radiotherapy

Question 13

Storage/disposal of LLW

Answer 13

Stored on sight until radioactive level is at safe levels - then disposed of as normal waste, placed in steel cans and then buried in landfill sites OR passed through ion exchange to remove radioisotopes, diluted, and added to sea

Question 14

Sources for antibiotic waste

Answer 14

therapeutic use in aquaculture and household pets, growth promotion and prophylactic use in animal livestock, pest control, sanitisers in cleaning products and toiletries, sterilisation and culture selection in research and industry, improper drug disposal

Question 15

Tamiflu - green chem case study

Answer 15

Antiviral Tamiflu is manufactured from shikimic acid or salt shikimate
Shikimic acid present in low concentrations in a large number of plants - main used is star anise
Extraction involves lengthy chemical process with low yields - supply issues
In 2005 and 2009 there were Tamiflu supply issues due to high demand from influenza pandemics

Question 16

Tamiflu - inspiration for change

Answer 16

supply issues resulted in alternative methods for production of precursor - applications of green chem principles:
Production of shikimate from fermentation of genetically engineered bacteria
Harvesting of shikimate from pine needles - low yield but sustainable and readily renewable source
Extraction of shikimate from suspension cultures of the Indian Sweetgum tree (avoids genetic modification and inexpensive natural source)