Vitamin C is manufactured on a huge scale by Roche, a Swiss company. All over the world there are chemistry-based companies making organic molecules on scales varying from a few kilograms to thousands of tonnes per year. This is good news for students of organic chemistry: knowing how molecules behave and how to make them is a skill in demand, and it is an international job market. The petrochemicals industry consumes huge amounts of crude oil: the largest refi nery in the world, in Jamnagar, India, processes 200 million litres of crude oil every day. An alarm ingle large proportion of this is still just burnt as fuel, but some of it is purified or converted into organic compounds for use in the rest of the chemical industry. Some simple compounds are made both from oil and from plants. The ethanol used as a starting material to make other compounds in industry is largely made by the catalytic hydra tion of ethylene from oil. But ethanol is also used as a fuel, particularly in Brazil, where it is made by fermentation of sugar cane. Plants are extremely powerful organic chemical factories (with sugar cane being among the most efficient of all of them). Photosynthesis extracts car bon dioxide directly from the air and uses solar energy to reduce it to form less oxygen-rich organic compounds from which energy can be re-extracted by combustion. Biodiesel is made in a similar way from the fatty acid components of plant oils.

Plastics and polymers take much of the production of the petrochemical industry in the form of monomers such as styrene, acrylates, and vinyl chloride. The products of this enormous industry are everything made of plastic, including solid plastics for household goods and furniture, fibers for clothes (over 25 million tonnes per annum), elastic polymers for car tyres, light bubble-filled polymers for packing, and so on. Worldwide 100 million tonnes of polymers are made per year and PVC manufacture alone employs over 50,000 people to make over 20 million tones per year. Many adhesives work by polymerization of monomers, which can be applied as a simple solution. You can glue almost anything with ‘superglue’, a polymer of methyl cyanoacrylate. Washing-up bowls are made of the polymer polyethylene but the detergent you put in them belongs to another branch of the chemical industry—companies like Unilever and Procter and Gamble produce detergent, cleaners, bleaches, and polishes, along with soaps, gels, cos metics, and shaving foams. These products may smell of lemon, lavender, or sandalwood but they too mostly come from the oil industry. Products of this kind tend to underplay their petrochemical origins and claim affinity with the perceived freshness and cleanliness of the natural world. They also try to tell us, after a fashion, what they contain. Try this example—the list of contents from a well-known brand of shower gel, which we are reassuringly told is ‘packed with natural stuff’ (including 10 ‘real’ lemons) and contains ‘100% pure and natural lemon and tea tree essential oils. It doesn’t all make sense to us, but here is a possible interpretation. We certainly hope this book will set you on the path of understanding the sense (and the nonsense!) of this sort of thing.

The particular detergents, surfactants, acids, viscosity controllers, and so on are chosen to blend together to give a smooth gel. The result should feel, smell, and look attractive and work as an effective detergent and shampoo (some of the compounds are added for their moisturizing and anti-electrostatic effect on hair). The yellow colour and lemon scent are considered fresh and clean by the customer. Several of the ingredients are added as pure compounds; the ones which aren’t are mixtures of isomers or polymers; the most impure are the mixtures of hydrocarbons referred to as the ‘pure and natural’ essential oils. Is it ‘packed with natural stuff’? Indeed, it is. It all comes from natural sources; the principal one being decomposed carboniferous forests trapped for millions of years underground. The coloration of manufactured goods is a huge business, with a range of intense colours required for dyeing cloth, colouring plastic and paper, painting walls, and so on. Leaders in this area are companies such as Akzo Nobel, which had sales of €14.6 bn in 2010. One of the most commonly used dyestuffs is indigo, an ancient dye that used to be isolated from plants but is now made from petrochemical feedstocks. It is the colour of blue jeans. More modern dyestuffs can be represented by the benzodifuranones developed by ICI, which are used for colouring synthetic fabrics like polyesters (red), the phthalocyanine–metal complexes (typi cally blue or green), or the ‘high-performance’ red pigment DPP

(1,4-diketopyrrolo[3,4-c] pyrroles) series developed by Ciba-Geigy.

The scent of the shower gel above came from a mixture of plant extracts with the pure com pound (in fact a mixture of two isomers) Citral. The big fragrance and flavouring companies (such as Firmenich, International Flavors and Fragrances, and Givaudan) deal in both naturals and synthetics—‘naturals’ are mixtures of compounds extracted from plants—leaves, seeds, and flowers. ‘Synthetics’ are single compounds, sometimes present in plant-derived sources and sometime newly designed molecules, which are mixed with each other and with ‘naturals’ to build up a scent. A typical perfume will contain 5–10% fragrance molecules in an ethanol/water (about 90:10) mixture. So, the perfumery industry needs a very large amount of ethanol and, you might think, not much perfumery material. In fact, important fragrances like jasmine are produced on a >10,000 tonnes per annum scale. The cost of a pure perfume ingredient like cis-jasmone (p. 2), the main ingredient of jasmine, may be several hundred pounds, dollars, or euros per gram.

Chemists produce synthetic flavourings such as ‘smoky bacon’ and even ‘chocolate’. Meaty flavours come from simple heterocycles such as alkyl pyrazines (present in coffee as well as roast meat) and furonol, originally found in pineapples. Compounds such as corylone and maltol give caramel and meaty flavours. Mixtures of these and other synthetic compounds can be ‘tuned’ to taste like many roasted foods from fresh bread to coffee and barbecued meat. Some flavouring compounds are also perfumes and may also be used as an intermediate in making other compounds. Vanillin is the main component of the flavour of vanilla, but is manufactured on a large scale for many other uses too.

Food chemistry includes much larger-scale items than flavours. Sweeteners such as sugar itself are isolated from plants on an enormous scale. You saw sucrose on p. 3, but other sweet eners such as saccharin (discovered in 1879!) and aspartame (1965) are made on a sizeable scale. Aspartame is a compound of two of the natural amino acids present in all living things and over 10,000 tonnes per annum are made by the NutraSweet company.

One of the great revolutions of modern life has been the expectation that humans will survive diseases because of a specifi cally designed treatment. In the developed world, people live to old age because infections which used to kill can now be cured or kept at bay. Antibiotics are our defence against bacteria, preventing them from multiplying. One of the most successful of these is Beecham amoxycillin, which was developed by SmithKline. The four-membered ring at the heart of the molecule is the β-lactam, which targets the diease-causing bacteria. Medicinal chemists also protect us from the insidious threat of viruses which use the body’s own biochemistry to replicate. Tamifl u is a line of defence against the ever-present danger of a flu epidemic, while ritonivir is one of the most advanced drugs designed to prevent replication of HIV and to slow down or prevent the onset of AIDS.

The best-selling current drugs are largely designed to address the human body’s own fail ings. Sales of Lipitor and Nexium both topped $5bn in 2009, fi gures which serve to illustrate the financial scale of developing safe and effective new treatments. Lipitor is one of the class of drugs known as statins, widely prescribed to control cholesterol levels in older people. Nexium is a proton pump inhibitor, which works to reduce peptic and duodenal ulcers. Sales of Glivec (developed by Novartis and introduced in 2001) are far smaller, but to those suffering from certain cancers such as leukaemia it can be a lifesaver.

We cannot maintain our present high density of population in the developed world, nor deal with malnutrition in the developing world unless we preserve our food supply from attacks by insects and fungi and from competition by weeds. The world market for agrochemicals produced by multinationals such as Bayer CropScience and Syngenta is over £10bn per annum divided between herbicides, fungicides, and insecticides. Many of the early agrochemicals were phased out as they were persistent environmental pollutants. Modern agrochemicals have to pass stringent environmental safety tests. The most famous modern insecticides are modelled on the plant-derived pyrethrins, stabilized against degradation in sunlight by chemical modifi cation (the brown and green portions of decamethrin) and targeted to specifi c insects on specifi c crops. Decamethrin has a safety fac tor of >10,000 for mustard beetles over mammals, can be applied at only 10 grams per hectare (about one level tablespoon per football pitch), and leaves no significant environmental residue.

As you learn more chemistry, you will appreciate how remarkable it is that Nature should produce the three-membered rings in these compounds and that chemists should use them in bulk compounds to be sprayed on crops in fi elds. Even more remarkable in some ways are the fungicides based on a five-membered ring containing three nitrogen atoms—the triazole ring. These compounds inhibit an enzyme present in fungi but not in plants or animals. Fungal diseases are a real threat: as in the Irish potato famine of the nineteenth century, the various fungal blights, blotches, rots, rusts, smuts, and mildews can overwhelm any crop in a short time.