(AV04392) What the chemist found in Pandora's box 2/2

declaring that they didn’t know what to do with the first world war helped this problem because in 1950 chlorine was introduced as a war gas on the western front by the germans they were the british were not long behind parents so they’re just as good solvents as their parents were since the beginning of the 19th century the solvents have increasibly come to be carbon tetrachloride and other related materials all chlorinated hydrocarbons the real boon in using up that chlorine though was the automobile about 1920 tetraethyl lead was introduced gasoline as an antinoc agent this was developed by thomas midgley of of general motors corporation tetraethyl lead does not contain any chlorine but it’s made from ethyl chloride ethyl chloride is the material i said was one of the two chlorinated hydrocarbons described before 1800 it’s made from alcohol and hydrochloric acid that material with lead are the raw materials for tetraethyl lead now this tetraethylead in your engine leaves a lay a coating of of lead on the engine and that has to be removed it’s removed with what’s called a scavenger the material that will dissolve this lead while it’s freshly deposited and hot the best scavenger turned out to be ethylene chloride the dutch liquid which is the other substance chlorinated hydrocarbon that i said was known before eighteen hundred about 1926 they began to introduce glycol antifreeze glycol antifreeze is also made from ethylene chloride in 1928 midgley who worked for the general motors corporation and was actually a mechanical engineer developed the refrigerant known as freon which has been universal ever since in modern refrigerating plants that is a that is a compound in which some of the chlorine some of the hydrogen in methane has been replaced by chlorine and some by fluorine which is a compound that’s related to chlorine i think it’s time to get that slide back i hope that i can remove a few confusions first of all this here is the reaction done by basil valentine before 1600 there’s alcohol with which some of you are probably familiar hydrochloric acid and you get what i call here monochlorobenzene monochloroethane i’m not sure that’s what i called it before but anyway i’m not going to want to worry about that these things all have several names unfortunately the number two refers to the reaction between chlorine and ethylene which you see up at the top there in which those double bonds have been removed by being filled in with chlorine ch2cl ch2clch2cl which of course can also be written c2 h4 cl2 uh well here’s chloroform which i’ve already described here’s carbon tetrachloride you see they are they’re derived from that simplest hydrocarbon that i had on the top these two are also used in dry and dry cleaning very extensively now and they have a double bond in them but you can see that various quantities of h have been replaced by cl in this case three out of four in this case four out of four yeah can you get it up a little higher thank you that’s far enough uh this uh now here are the fluorocarbons the compounds i just mentioned which have both fluorine and chlorine in them including this freon refrigerant it’s a strange kind of a compound majorly must have been an extraordinarily clever man to have figured out some of the things he did apparently the uh the reason he comes up with it came up with this is because in a refrigerant you want something that has just the right boiling point so you can keep boiling it and condensing it easily at about room temperature you also want something that’s non-toxic so if it leaks out into the room it won’t kill you the these compounds that initially guessed the compound of this kind would fill a bill he made some and they actually worked

they should be called they’re called fluorocarbons that’s what he called them but that implies that it’s all fluorine but there’s both chlorine and fluorine so that’s a misnomer but that’s what they call them so that’s what i’ll call them finally as also we can get rid of this chart once and for all item eight here i don’t know how well you can see this i guess i’ll just have to hope is it focusable uh a number eight seems to be pretty bad i can hardly see it myself there we go that’s better thank you ch2 and then there’s a double bond chcl for some reason that’s called vental chloride you notice that it really is related to these things not very different one point i want to make here is how simple all these things are i’m sure you know how complicated organic molecules are nowadays that you see in textbooks but these things are about as simple as they can get dental chloride you’ve probably heard of too well that’s what it is and i’ll come back to it in a few minutes thanks may i have the light please well so the problem is on the way to solution uh at least the automobile and the ex the replacement of inflammable by non-inflammable solvents went a long ways to solve the chlorine problem but then the second world war ensured the solution of the chlorine problem about 1940 somebody discovered that freon this material which i just described as refrigerant if you put it in a sealed can with a liquid you pick up the can with your hand the freon or the fluorocarbon evaporates produces pressure inside the can and you can squirt the fluid out the aerosol can had been invented it was first used to spray medicines in american troops used by the american troops in the pacific war since then the use of it must be all too familiar to you also in the second world war they attempted to make artificial rubber and succeeded in doing so among the artificial among the materials they tried to use were chlorinated hydrocarbons like vinyl chloride which polymerized that means that the under certain physical conditions the molecules connect in long chains and become solid materials names like thiaco neoprene were the names of artificial rubbers during second world war and the most well-known of them was vinyl chloride they were not very much like rubber sometimes but they were used for plastics vinyl chloride came out of the war as one of the most widely used plastics making phonographs car seat covers almost all car seat covers are made out of vinyl chloride plastic electric insulation and so on this material ventilated had been discovered in 1835 and this application not made until 1940 over 100 years later 1942 ddt was introduced as an insecticide that is a chlorinated hydrocarbon a little more complicated than these but it had been known since 1874. it was a miracle pesticide it’s been followed up by a lot of others by 1970 we read outcries in the chemical literature about the sodium problem this alkali industry is now operated mainly to produce chlorine and there are not enough uses for sodium to uh make it economical so this is the current worry the per capita consumption of chlorine in the united states in 1935 was three and a half pounds that’s 1935. 1955 it was 41 pounds 1975 is 100 pounds 55 percent of the salt made in this country and we have by far the world’s largest production is used to make chlorine prime that’s the primary purpose of producing the salt is to produce chlorine and of that chlorine the number the proportion which is estimated to go into chlorine added hydrocarbons is estimated up to 70 percent these are data from recent years the united states consumption of vinyl chloride in 1973 was five and a half billion pounds ethylene chloride the dutch liquid eight billion pounds made in 1973 these are billions in 19 as early as 1960 670 million aerosol cans were manufactured in the united states during the generation between 18 1930 and 1960 the per capita consumption of

all of these things together solvents plastics pesticides only the ones containing chlorine increased on an average of nearly 20 times 20 fold that is to say in 1960 we were using 20 times as much of these things as we were in 1930 so muskrat you see has been vindicated chemical research is useful after all what was the matter with those 19th century chemists well one thing that was the matter with them might have been that they thought in using the chlorinated hydrocarbons to develop a theory of organic chemistry they were actually making them useful and it wasn’t necessary to do more another thing that must be said of the 19 early 19th century chemist that they were very short time about two generations away from alchemy and they were not very anxious to get back into the kind of muddled mysticism and empiricism which they were trying to free chemistry from chemistry was hardly a science before the 19th century the followers of musprat the practical chemists the practical chemical engineers certainly did not accomplish much in the solution to the chlorine problem during the rest of the 19th century in fact they accomplished so little that that may have something to do with why chemical engineering became an academic discipline in the 20th century instead of purely something you go out and learn by working in the works the educated engineer of the 20th century is the person who’s responsible for these marvelous marvelously useful things but of course you got them from reading all books written by chemists of nearly 100 years earlier the most important thing to say about it well uh before i i come to that i i would say something that’s probably not necessary to say because you must know it if you don’t know it you should check up on yourself ddt has proven to have so many harmful side effects that has been more or less banned in 1975 the james river in virginia and much of of chesapeake bay were poisoned by something called capone which is another chlorinated hydrocarbon insecticide in 1976 a town called mata north of milan in italy was abandoned because it was an explosion of something called tcdd something called pcb has been coming down the hudson river and is the second most polluting material in the sea along the atlantic coast these acronyms and trade names all cover chlorinated hydrocarbons and as a matter of fact here is this morning’s washington post i read on the airplane you probably can’t read that from here but the top line says chloroform in northern virginia water exceeds safety level that’s why i said that i i didn’t know whether i really needed to go into this this one is an interesting wrinkle i must say it seems that the chlorination of the drinking water in northern virginia is encountering encountering meth and methane which is generated by sewage which is also getting in drinking water of northern virginia and the two of them together are making chloroforms the solvents the solvents those solvents that are not exploding are evaporating into the atmosphere at approximately the same rate as they’re being manufactured today the aerosol their fluorocarbons are charged with threatening the survival of the ozone layer to which they ascend the solids like vinyl chloride resins end up as indigestible junk because they’re not biodegradable or if they are heated strongly they disintegrate to form chlorine hydrochloric acid and fosgene a couple of workmen were killed in a washington building recently when an electrical shortage occurred in a high voltage line the heat disintegrated the insulation which is vinyl chloride and produced chlorine hydrochloric acid and phosgene

however once that’s all pointed out it needs also to be pointed out the ddt stopped the insect plagues when i was young i spent my summer vacations in south dakota in the 30s and i remember the grasshoppers coming over the hill in a solid cloud i remember i think it was something called chinch bug that destroyed the iowa corn crop on a number of occasions there’s the other side of it ddt stopped them probably not permanently but anyone who remembers those uh the insects that infected this region in the 30s will go a little slow in criticizing at least criticizing the people who tried ddt furthermore the chlorinated hydrocarbon solvents did prevent fire the plastics have replaced metals which would have probably run out before now if they hadn’t now one factor i think so i don’t think there is much point in pursuing who is to be praised and who’s to be blamed for this but there is something i want to conclude with which i think is worth thinking about the factor here is one of scale it seems to me it’s the scale on which everything is done today and i want to introduce my few remarks about that with a quotation from galileo the celebrated father of the scientific revolution who wrote a famous book in 1838 called two new sciences the two new sciences one of them was mechanics he is the in that book he gives a mathematical expression for following the behavior of falling bodies like stones and that is is probably the first step in the famous scientific revolution of the 17th century that’s what this book is used for but there’s another science in that book strength of materials we call it the he studied what it took to break a beam the the venetian dockyard was famous for its huge cranes and so galileo writes about that and he begins that book with some words like the following which i’ll paraphrase there are is the dialogue between two people called salviadi and segreto salviati says experience with a famous arsenal in venice seems to me to open a large field of to speculative minds and particularly in that area which is called mechanics because they have so many different kinds of machines then segredo says indeed i’ve sometimes been thrown into confusion and have despaired of understanding how some things can happen that i see there salviati you mean when we were trying to comprehend the reason why they make the sustaining apparatus supports blocks and other things so much larger around those huge galleys than they do around little boats segreto i do mean that and particularly what we’ve noticed that i have always considered to be an idle notion of the common people that one cannot reason from the small to the large because so many mechanical devices succeed on a small scale that cannot succeed in great size now all reasonings about mechanics have their foundations in geometry and i don’t see why largeness and smallness make any difficult any difference in things like circles they don’t change big circles don’t have different properties than small circles so why should big cranes in dockyards have different properties than small cranes and big weights than small weights and large scale the small scale well there is an answer to that in the science of applied mechanics when a crane it’s a complicated answer but just to give you a rough idea when the crane gets too big the weight of the crane itself becomes a factor in the whole operation you’re performing but you will have no difficulty i think in thinking of cases where somebody has made a model of something that worked fine that wouldn’t work in full size many people flew airplanes models before anyone ever succeed in flying a full-scale airplane for example well that’s i think is what is going on in our society the cyclotron laboratory is not just a bigger physics laboratory there’s something about it that’s different in kind a hospital using instrumental diagnosis is not just an enlargement of the family physician a scientific society with 160 000 members is not just an enlarged version of the royal

society of london a corporation is not just a big company and a war machine is not just a big army we might like to go back to the string and sealing wax laboratory the country doctor small business or the cavalry we can’t do it because they’re too many of us there were about a billion people in the world in 1800 when malthus was explaining why it couldn’t accommodate anymore in 1907 there were about a billion six a hundred million in 1960 there were three billion 220 million people that’s an increase in scale too everything is increased in scale and i think that to solve problems which need to be solved obviously it would help if we could manage to think or discover or do research on what the significance is of the increasing scale rather than go back and try and find the hero who developed something you like or the villain who develops who introduced something you don’t like they weren’t heroes or villains they couldn’t foresee the future any better than we can they couldn’t foresee the scale on which all these things are done and so i it as an approach to the study of the questions of which this seminar is concerned and my justification for introducing the chlorinated hydrocarbons is i think they’re a very striking example of the problem thank you the space that a person would archetype when you start thinking it is change scale well in that case the the impressive thing of course is changing from a 20-fold increase in the use of chlorine in this in a short period of time is the uh thought-provoking part of it the question of how much chlorine the the where the world can stand or or better how much how many man-made materials can the world stand these are man-made materials all of them and uh except chlorine itself and how much of that can the earth stand well i my guess i don’t know that’s the kind of thing the environmental protection agency is very likely to give somebody a grant for uh it’s uh but that you can even raise such raise such questions is uh a suggestion that that one ought to start thinking about because there are all sorts of aspects of this that that lead to that conclusion i i don’t know whether i’ve answered your question or not have i probably as well yeah as far as the 100 consumption of a hundred pound of chlorine per person is concerned the only significant thing about it i think is that it’s about 20 times as much as people were consuming a generation earlier a timeline between some of the hydrocarbons invented in the 19th century and which did not come to the earth until 1948 1941 is just also um a dimension of of um the present days that things get um put into production almost as soon as they’re invented yeah they’re all kind of this is sort of interesting from the point of view of time lags i don’t think it fits any theory i ever heard about time lags i’ve heard papers where people say in the 19th century the time lag was such and such in the 20th century is reduced to some other very small number well maybe so this case suggests that that the uh the time lag i don’t think represents much of anything it was it was the chlorine problem needed

to be solved and when the chlorine problem needed to be solved they went back in those old books and found these century-old substances they also found that the chemist had described their property those the chemists who made them in the first place said the more chlorine you put in the less inflammable it gets what was needed was for somebody to say we ought to have you know non-inflammable solvents but they went on using inflammable solvents through the 19th century and one wonders if they ever would have introduced non-inflammable solvents if it hadn’t been for the chlorine salesman who had all this chlorine to get rid of i mean i’ve got not got much better explanation than that to offer i have no theory about time lag i don’t see any there the chlorine problem of the 20th century is surely what brought all these immense uses into being they gave an incentive in other words we should expect a proliferation of sodium products as well products are generally biodegradable as far as i know but uh i don’t know that i could say any more than that about what we should do this schwingler school of chemistry for seed problems with inventing these sort of non-natural substances like like we’re talking about now i’m sorry would you say it again i guess i found the swindler school the people who objected to making the idol garments oh the objection to the hydrocarbons was not to making them it was to the affront that this whole this whole method a theory of organic chemistry gave to the traditional theory this was a typical inter-academic fight the traditional theory was that all compounds organic or otherwise consists of a positive part and a negative part and this chlorine the work was being done with chlorinated hydrocarbons seemed to contradict it because chlorine which was negative was replacing hydrogen which is positive this was a kind of an internal matter no no that uh there’s nothing about that in there it was simply an insult to the fathers of the science who had posed the old theory that was being replaced nothing more to it than that they were made in small quantities until these things began to be produced in enormous quantities the questions didn’t exist i mean nobody would get up and denounce dtt if only small amounts of it were being used there’d be no reason to yeah yeah sure scale that we live in the world dominated by scale but we reason about this world in terms of a world that’s gone not very long gone only about maybe 30 40 years ago but now hardly anything happens unless it happens on an enormous scale from the hula hoop to rock music to chlorinated hydrocarbons it’s worldwide on a mass scale and it becomes a different phenomenon that’s my argument sometimes the definition between what is natural and unnatural isn’t always obvious we forget for example in the case of thorim that there is a world where there’s lots of foreign right here on earth and that’s under the ocean under the ocean in the ocean well it exists there are sodium chloride no not all there are many pile melons any plants in the ocean indeed have chlorinated hydrocarbons in them is that so i didn’t know it are they edible most of them be very toxic to us but they must do something for me in their in their own society of mass problems and overreaction to them is something we have to live with today that the german canvas of the last century that has enjoyed just insulting each other in journals didn’t have and i think there are many examples of this in modern science modern scholarship that we face i think recombinant dna is one case where society as a whole is running scared and so they’re going

to put i think much too strict regulations on what a person can do or the use of of drugs of various kinds even in fairly innocuous ways now are under such a bureaucratic shield that it takes years to be able to inject a rat with some anesthetic because you have to about all of the the permissions from the federal government down to the city of ames to be able to do that so i think this this fact of backlash which has existed in all societies is with us in a very pernicious form today that is because there is a problem over which the scientist or the scholar has no control there tends to be over regulation of the scientists and over regulation of his creative efforts and i think if we’re talking about technology and society this is a problem which i don’t think many people are facing now that is of stifling creative effort because everybody’s running scared well i don’t think there’s any doubt that is the case and what i’m suggesting is a you