Author Topic: The Birth of Organosilicon Chemistry (Nonfiction)  (Read 2179 times)

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Gramps

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The Birth of Organosilicon Chemistry (Nonfiction)
« on: October 01, 2015, 07:42:10 AM »
Introduction

Organosilicon compounds contain carbon (organo) molecules and silicon molecules.  Silicone rubber is an organosilicon compound.  My father discovered a chemical reaction that opened the door to the manufacture of many organosilicon compounds, including silicone rubber.

Excerpt from my father's biography:

Organosilicon Chemistry

In 1944 I was moved from the automotive group at Linde [a division of Union Carbide] to a silicon chemistry group.  This was effected by handing me over to a new boss, Corneille O. Strother.  Strother was a highly qualified chemist with a Ph.D. in physical chemistry from Princeton followed by post-doctoral experience at Princeton, the University of Munich, and the Mellon Institute in Pittsburgh.  He was a member of the scholastically elite Phi Beta Kappa fraternity.  He had been raised in Atlanta.  In temperament, he was a southern gentleman with a short fuse.  We got along well, perhaps because we were both southerners but, more importantly, because each of us saw the other as a capable scientist.  Strother had excellent strategic judgement, as evidenced by his early recognition (before I joined Linde) of the importance of polyethylene, which at the time had no commercial use.  Thanks to his foresight, Union Carbide became the leading supplier of high-quality polyethylene for use in sonar and radar in World War II.

At first there was confusion as to whether I would continue helping the automotive group.  But when Strother indicated his preference that I work full-time on silicones, I of course took the same position.  This generated some hard feelings.  When automotive engineers came to me with problems, I had to tell them I was no longer in that line of work.
....
Soon I was the head of a group of five chemists.  We were to establish a business based on organosilicon chemicals.  The logic was that Union Carbide wanted to expand its chemical business.  Already it was a powerhouse in organic chemicals, number two in the nation, DuPont being number one.  Several companies were built on inorganic chemicals.  We saw a large undeveloped area in organometallic chemistry, i.e. chemicals where a metal atom is attached to an organic radical1.  Why would we want to insert a metal atom into an organic radical?  Because organic radicals are at the heart of an entire branch of chemistry (organic), and if we could learn how to make metallic analogs of organic radicals, we could create a vast new class of chemicals and then explore the potentials of these new chemicals for helping mankind.

At that time, there were 39 metals in the Periodic Table; and silicon, which is semimetallic, also interested us.  Which atom should we attach organics to?  For some time, this small group of chemists had wandered all over the Periodic Table--chromium, vanadium, and uranium.  For various reasons, Strother decided that we should stick to silicon.  For one thing, it is near carbon in the Periodic Table and should be compatible with it chemically.

Silicon "metal" (Si) was readily available from another division of Union Carbide.  But how to attach carbon to silicon, i.e. how do you make a C-Si bond?  Pages 124 through 128 of the Appendix tell the technical details of how I got over this hurdle and entered the realm of organosilicon chemistry, opening the way to 14 fascinating years of research in Linde's Tonawanda [NY] lab.

So now we had the basis of an organosilicon business--a way to make a variety of compounds.  Yet to be found were uses for the compounds.  So two new groups were started at Linde--a research group to find uses for the compounds and an engineering group to learn how to scale up the laboratory operations to plant size.

It was an exciting time.  We, the research group, converted chlorine-containing compounds, which were highly acidic, to benign liquids, oils, and polymers.  This vast group of chemicals was all unknown in nature and new to man.  They had unusual properties:  They were much more resistant to heat than organics, they were not wetted by water, and they had other unusual surface properties.  In 1940, sales of these compounds were zero.  Today [1997] about $2 billion worth of organosilicon compounds are sold in the USA every year.

Silicone rubber is used in caulking compounds around your home and in gaskets under the hood of your car.  All polyurethane foams, such as in pillows, chairs, and car dashboards, contain about 0.2% silicone surfactants to control the pore (bubble) size.  The surfactants are block copolymers2 of a synthetic lubricant like those discussed starting on page 75, and a silicone, so I had a big part in this.  Donald Bailey--a Ph.D. from Penn State University, a friend, and a valuable member of my Linde group--did the actual lab work for the inventing of silicone surfactants.

Another big use for organosilicon compounds is as coupling agents.  Fiberglass consists of glass fibers embedded in a resin.  The fiber strengthens the composite, but the bonding is poor if it is not first treated with an organosilicon compound.  The glass, which is mostly silicon oxide, adheres to the silicon end of the organosilicon compound, leaving the organic part (ethylene or some other unsaturated organic) waving in the breeze to attract the resin, which is organophilic (has a strong affinity for organic molecules).  The organic radical is tailored to the resin so that it has a similar appearance and composition.


1 An organic radical is a group of atoms that include carbon and commonly occur together in a particular compound.
2 Most copolymers are made by reacting two monomers (A+B) together at the same time to create a random distribution of the monomers in the copolymer, e.g. ABABABAB, etc.  In block copolymers you first make polymers AAAAAA and BBBBB and then react them together to get AAAAAA BBBBB.

dolling

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Re: The Birth of Organosilicon Chemistry (Nonfiction)
« Reply #1 on: October 01, 2015, 09:05:30 AM »
Well me doesnt understand much o that but its mitey intresting and thank gudness for silicone! Me looking forword to getting me first silicone toy ladee. Not happee without wive.
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Szalinski

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Re: The Birth of Organosilicon Chemistry (Nonfiction)
« Reply #2 on: October 07, 2015, 10:34:20 AM »
Well I found it interesting, if a bit tricky to follow at times (ORGANIC chemistry was never my forte'). And informative; I had always thought that silicon plastics were polymers in which the carbon was replaced by silicon, which as you state has compatible chemical properties.

If I remember correctly, it's the elements that are grouped together in a column that are considered to be a 'family', having similar traits and in some cases can be substituted in similar combinations with other elements. Silicon lies directly under carbon. O0
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Gramps

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Re: The Birth of Organosilicon Chemistry (Nonfiction)
« Reply #3 on: October 07, 2015, 05:57:41 PM »
Thanks for your comments, dolling and Szalinski.  My father was disappointed that Union Carbide and his work are never mentioned with regard to silicone compounds.  Even now you can look up "Silicone rubber" in Wikipedia, and Union Carbide is not even mentioned.  Yet they were the ones who patented the key chemical reaction.

I may try editing Wikipedia.

Gramps

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Technical Details
« Reply #4 on: October 13, 2015, 08:18:41 AM »
From the Appendix to my father's autobiography, these are the technical details:

"As we left this story on page 77, I was searching for the door to organosilicon chemistry.  So far, only two peepholes were known:
  • The Grignard1 Reaction, which had been used in universities but was too expensive for commercial use.2
  • The Direct Synthesis method, patented in 1941 by Eugene Rochow3 at General Electric Company:
Cu
2CH3Cl + Si (CH3)2SiCl2
This was a great invention, but it made only a few silicon compounds."4

(To be continued)

1Pronounced Green'yar.  The reaction was discovered by Victor Grignard in 1900.  It was a multistep reaction, usually carried out in a diethyl ether solution.  Diethyl ether is highly flammable and tends to concentrate explosive peroxides.  Just running the reaction in a laboratory, let alone on an industrial scale, required care and sophistication, both for safety and for avoiding cross-linkages that ruin the end product.
2Union Carbide had solid grounds for this decision.  Nevertheless the Dow Corning Corporation used the Grignard Reaction on an industrial scale to enter the silicone business with useful oils, resins, and elastomers.  Dow Corning must have found ways to improve the Grignard process.
3Dr. Rochow refereed a number of the papers that I wrote on silicones.  He was always gracious and kind in his dealings with me.
4Nevertheless, General Electric soon converted the Direct Synthesis method into an industrial process and erected a silicone producing plant at Waterford, New York.

AVTH

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Re: The Birth of Organosilicon Chemistry (Nonfiction)
« Reply #5 on: October 14, 2015, 05:00:44 PM »
Wikipedia: https://en.wikipedia.org/wiki/Silicone
Tetraethyl orthosilicate (TEOS) https://en.wikipedia.org/wiki/Tetraethyl_orthosilicate

There is same kind range of silicones as hydrocarbons. Also volatile silicones (solvents).

Quote
The use of silicones in electronics is not without problems, however. Silicones are relatively expensive and can be attacked by solvents. Silicone easily migrates as either a liquid or vapor onto other components.

Silicone contamination of electrical switch contacts can lead to failures by causing an increase in contact resistance, often late in the life of the contact, well after any testing is completed.[6][7] Use of silicone-based spray products in electronic devices during maintenance or repairs can cause later failures.

I have also experiences about this... Don't use silicone spray for lubricating mechatronics with electronics. Use silicone oil/grease accurately. (But it is difficult to purchase plain silicone oils. Car care silicone sprays are usually mostly butane.)

Quote
Leak of silicone in biological tissues produces an inflammatory reaction, as silicone-induced granuloma (siliconoma)
This is same kind problem as micro plastic in oceans. https://en.wikipedia.org/wiki/Microplastics Silicone itself is nontoxic as many plastics.
When harmful substances was absorbed from body to silicone oil (microbiological residues or toxins). Therefore silicone oil is used also in vaccines as adjuvant (for boosting immune system reactions by residues of agent that resembles a disease-causing micro-organism).

(I was explored these things due opinions of my therapist.)

Gramps

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Re: The Birth of Organosilicon Chemistry (Nonfiction)
« Reply #6 on: October 23, 2015, 12:09:05 AM »
Thanks, AVTH, for sharing your expertise as a user of silicones.  It is a huge topic.  My father's discovery opened up a whole new branch of the Beilstein database of chemical compounds.  Now to return to the story:

(Continued from October 13, still quoting my father:)

"While reading, thinking, and studying this problem one day in early 1946 in the Linde library, it occurred to me like a flash that an SiH bond should react with C=C and C≡C bonds to make Si-C bonds.1  I tried this in the lab using a platinum catalyst with the following reactants:



The reaction was vigorous and complete and occurred at 100º-200ºC lower than the uncatalyzed reaction.  I tried it with innumerable C=C and C≡C bonded compounds, and most reacted.  Silicon could be attached to almost any organic radical.  I knew that this was a patentable discovery, so I followed the rules to a T:  I wrote up an idea record, had it witnessed, and signed it."

(To be continued)

1 Bond energy calculations confirmed that such reactions should be thermodynamically favorable and energetic.

Gramps

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Re: The Birth of Organosilicon Chemistry (Nonfiction)
« Reply #7 on: November 08, 2015, 11:41:23 PM »
(Continuing from October 22, still quoting from my father:)

"By substituting different alkenes for the ethylene, I could change the result from ethyl trichlorosilane to other alkyltrichlorosilanes, and of even greater interest, to organofunctional alkyl chlorosilanes.1   By substituting acetylene, I produced vinyl trichlorosilane.

Trichlorosilane (also called silicochloroform, so named because Si has replaced the C in chloroform [formula CHCl3]) is readily prepared as follows:

Cu
3HCl + Si →SiHCl3+H2

Trichlorosilane soon became very important, as we shall see in the next section.

Thus began my 14 years of organosilicon research.

The early books on the history of silicones, one from Dow Corning and one from General Electric, afforded little space, outside of a footnote, to the platinum catalyzed carbon-bond reaction.  But these authors wrote silicone history from the viewpoints of their laboratories.  The full history of silicones at Union Carbide still remains to be told.  In the long run I have no doubt that the Wagner reaction will rest right beside the Rochow and Grignard reactions in importance."


1 Acrylonitrile (CH2=CHCN) required a special base type catalyst, as worked out by Dr. V. B. Jex, to give CNC2H2SiCl3, which could be converted to either the amino or the carboxy silane.  The γ-aminopropyl tri-ethoxysilane and its analogs were found by one of the glass companies to be the best coupling agent for epoxy resins and were eventually used around the world for this purpose.

Ray Rentell

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Re: The Birth of Organosilicon Chemistry (Nonfiction)
« Reply #8 on: November 09, 2015, 04:12:42 AM »
Science was never my strong point at school so I do not comprehend any of this thread. :(

All I can say is a huge thank you to your father and all who bought silicone into the world, otherwise we would not have our fine dolls.
for album click the pic

Gramps

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Re: The Birth of Organosilicon Chemistry (Nonfiction)
« Reply #9 on: November 09, 2015, 12:05:12 PM »
Same here, Ray.  You'd think that with a scientist father, I would have been good at science.  But I'm not.

I understand this thread at a cook-in-the-kitchen level.  As Mahtek once explained to me, chemistry is just a bunch of recipes.
(Then he went on to explain how silicones behave at the molecular level.  :-\ )