The Chemical History of a Candle

The "Chemical History Of A Candle" by Michael Faraday, is perhaps the most popular science book ever published. It has been published continuously since 1861. By design, the book is a series of lecture notes given by Faraday at his annual Christmas Lectures, beginning around 1849 in London. Faraday was a science celebrity in his lifetime, but much more so than those we have today because they lack such career achievements in science as his.

In this simple series of lectures, Faraday ties together much of what was know about chemistry and physics, simply by considering a burning candle. What I love about this first lecture is the way Faraday demonstrates what a perfect storage medium of energy the wax candle is. Hydrocarbons are our friends -- not something to be demonized.

 

link

Exceeding Nature

Original

The scheme belongs to a recent chemistry paper entitled "Nonmetal Catalyzed Hydrogenation Of Carbonyl Compounds" which I think shows significant advancement in chemistry. For the non-chemist, I'll unpack the title.

You may not be interested in hydrogenation, but hydrogenation is interested in you: it feeds you. The metal-catalyzed hydrogenation of vegetable oils is big business. You may have gotten away from trans-fats, but are you free of cis-fats?  How about saturated fats? The food industry uses hydrogen and metals like nickel to hydrogenate food stuffs. And then there is the "hydrogenation" of nitrogen to make fertilizer.

What these guys in London did is remarkable because they used hydrogen (H₂) to make alcohols (top right) from ketones (top left). And they used only C, H, O, B, and F atoms, spatially arranged as shown. No metals.

Nature has little use for H₂, the simplest of molecules. Relatively little free H₂ exists on earth. There is a class of enzymes called hydrogenases, but guess what? They use metals to activate H₂. So this work goes above and beyond Nature itself.

You Wanna Picture Or 1000 Words?

This is part of the problem, not the solution:

Of course, it's all according to plan. Link

Pure Morpheme Drip

I just rediscovered the word morpheme and realized that that was what I wanted to call purine here.

Purine is a chemical morpheme. Not the word purine, but the two fused rings. There are other chemical morphemes, of course, but that's what I was trying to convey back there.

When I google "chemical morpheme" I get this, which is kinda sorta what I mean.

Pure Enjoyment

Consider all the English words based around the Greek word logos--derived words like catalog, prologue, dialogue, logogram, zoology, even blog...it's a root word with countless derivatives. Logos is to words what the substance purine is to the chemistry of life.

Purine is ubiquitous and underlies a great deal of biochemistry. It, along with the even simpler pyrimidine, are the core base pairs in DNA and RNA. Purine is also the basis for a surprising number of familiar Genußmittel--things like caffeine and theobromine (the stimulant in chocolate). The German word Genußmittel is bit like Schadenfreude and has no literal equivalent--the best translation is perhaps "means of enjoyment."  Our own English word (which the French also use) is stimulant.

Of course, purines are not everything--there are also sugars, and amino acids too, which are completely different entities.  Diversity. But we owe our first taste of purine, and the apt name, to a German chemist named Emil Fischer.

Synthesis v. Analysis

Around the time that America began civil warfare, reports of a new chemical element came from the relative tranquility of Germany. Robert Bunsen and Gustav Kirchhoff reported in 1861:

Supported by unambiguous results of the spectral-analytical method, we believe we can state right now that there is a fourth metal in the alkali group besides potassium, sodium, and lithium, and it has a simple characteristic spectrum like lithium; a metal that shows only two lines in our apparatus: a faint blue one, almost coinciding with strontium, and another blue one a little further to the violet end of the spectrum and as strong and as clearly defined as the lithium line.

They had discovered cesium which they named after the Latin word meaning "sky blue." 

There had been a 15 year lull in finding new chemical elements between about 1845 and 1860. One reason for this was that many of the "easy" elements had already been exhumed in measurable enough quantities. Here is a timeline of element discovery: link 

The mid-19th century saw advances in both chemical synthesis and chemical analysis. Chemical synthesis, obviously, involves putting things together; analysis means tearing substances down to find out what's there (the same dichotomy exists in writing).

Decades before Bunsen and Kirchoff, Humphry Davy proved the existence of new chemical elements by making them: he electrolyzed sodium and potassium salts, reducing Na⁺ and K⁺ cations to their neutral metals.*  Now Bunsen and Kirchhoff had shown the same level of proof through analysis without synthesizing the new element. This paradigm shift was profound and rapidly accelerated the discovery of newer elements (see the timeline).  The next few newly-discovered elements were all named for their unique colors in flame spectra.

Around the same time as Bunsen and Kirchoff, the nascent science (really art) of organic chemistry still lagged because there was no convincing method of analysis which could prove a new organic compound.  There was only combustion analysis--invented in the 1820s by Joseph Louis Gay-Lussac and Justus von Liebig--which involved burning a sample to determine its carbon, hydrogen, and nitrogen ratios.  And so, for the time being, the proof of a new organic compound's structure found in nature lay in making it synthetically. Thus began a long and rich tradition of synthetic organic chemistry. It took until the end of the Second World War for analytical methods to catch up.
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*The verb "to reduce," in the chemical sense, derives from Latin using the notions of re + ducere = to lead back to (the element).

Рутений Made It Possible

Ruthenium, or Рутений in Russian, was named for Russia. We should call the element russium--that would at least be more historically descriptive--but ruthenium it is.* The first detectable amounts came from platinum ores in the Ural mountains--first discovered in the 1820's. The element is exceedingly rare--and thus expensive--and yet it too has its unique chemical niche. 

Ruthenium is the first element in the series 1 to 44 which can be fully stripped of 8 electrons to give a stable oxidation state of VIII.** Step just one atomic number backwards, to technetium, and there aren't 8 valence electrons to lose--only 7; step one element to the right, to rhodium, and the nucleus is already too electronegative to give up more than 6 electrons.  This makes ruthenium special--its willingness to fully yield to rapacious oxygen.

Ruthenium isn't really famous for much. It enjoyed brief fame in 1952 when ruthenocene was prepared by analogy to ferrocene, but it always seemed a little under-represented in catalysis until a chemist named Robert Grubbs (originally from Possum Trot holler in Kentucky), put ruthenium on the map with his Nobel-prize winning work centered around olefin metathesis.

"Olefin metathesis" has interesting history as a term--taken apart, "olefin" comes from oléfiant which means oil-forming and which ultimately comes from the roots oleum + facere. Olefin is an old word as chemistry words go--not so old to be practically archaic like oleum or vitriol, but still old. The modern term for olefin is alkene--organic hydrocarbons having one or more unsaturated double bond. The terms "polyunsaturated fat" and "trans fat" refer to olefins, FWIW.

Metathesis is a special word meaning rearrangement. There's a grammatical sense of the word which means transposition, and the chemical sense is just a metaphor. If we let the equal sign be a double bond, olefin metathesis refers to

a=b + c=d --> a=c + b=d.

See what happened there? Transposition.
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*Ruthenia corresponded to a much smaller region of what is now in the Ukraine. The Ural region was unknown to the Romans.
**Wikipedia notes claims to the existence of Fe(VIII) as in FeO₄ but the claim is tentative.

Zirconium Rhymes With Titanium

Zirconium has a long, illustrious history in jewelery. The element's name derives from an ancient word for the gemstone, zircon.  The element is more commonly found in cubic zirconia, which--thanks to the Soviet method for making it using the so-called skull process--is cheap and plentiful.

Zirconium rhymes with titanium. Often, such transition-metal family members mimic each other. Zirconium, like titanium, is a valuable catalyst for making plastics. I know--yawn. But catalysis is an intellectually interesting aspect of chemistry--one which has "real-life" analogy--much like status quo and change.

Catalysts are classified as "heterogeneous" or "homogeneous" depending on whether they mix freely with hoi polloi substrates. "Heterogeneous" means that the catalyst stays in a different phase than whatever it's working on--e.g., a catalytic converter working on gas phase exhaust. Homogeneous catalysts swim in a liquid phase like everything else around it--in a single phase.

First generation Ziegler-Natta catalysts were heterogeneous. Catalysis happened at the edges or face of a chunk or pellet.  Obviously, a lot of unused catalyst lies buried inside- and is wasted. Homogeneous catalysts are known for their "atom efficiency"-- a concept that becomes more important for rarer platinum group metals.

Just A Thought...

cuban bob wrote: Our local NPR station had a big story on Monday about how this is killing the funding for highway maintenance.

This reminded me of Ken Burns' "Prohibition" when he taught how a potential loss in federal tax on alcohol was a major deterrent for enacting Prohibition--the Feds wondered how they could recoup losses if such a national prohibition law were to pass. But the 16th Amendment (Federal Income Tax) nicely solved that in 1913 and paved the way for the subsequent Volstead Act.

Beware any national energy tax to offset declining fuel tax revenues--it could be a prelude to a stricter prohibition on hydrocarbons.
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crossposted at Althouse

Conversations with Henry

Henry: "Isoelectronic" is a perfectly fine concept. No need for you to feel it's inadequate. I'll give you an even easier example. We can play the same game with carbon, nitrogen, and oxygen:

[Henry sketches the Lewis structures for N₂ and CO]:

Henry:  Forget about the labels "C", "N", and "O" for a moment.  Don't let them color your thoughts. Think of them as the numbers 12, 14, and 16:

Me:  OK, but what does the little curved arrow 1p, 1n mean in your picture?

Henry:  That's your little Maxwell's Demon, moving a proton and a neutron from one side to the other. There's no net loss or gain, but rather just a transfer.

Me: Are you pushing electrons too?

Henry: No! The electrons haven't moved yet but they feel the polarization: suddenly there's an extra charge on the oxygen side and one less charge on the carbon side. The electrons rearrange, being drawn slightly closer to the oxygen, but not completely, and the carbon, having less positive nuclear charge, is polarized negatively by the electrons. The molecules electron's are polarized like this:

Me: Ah, that explains why carbon monoxide binds to metals like iron in hemoglobin via its carbon.

Gallium Arsenide is Germane to Solar Cells

Gallium arsenide, a simple combination of two elements, interconverts light and electricity; GaAs lasers turn electricity into light and GaAs solar panels convert light back into electricity. There are alternative combinations of elements for these tasks, but each has its limits. What strikes me is how gallium and arsenic bookend germanium:

I need a name for "binary combination of elements which brackets and mimics another element." The term isoelectronic is close but doesn't cut it for me. There is a mathematical symmetry about GaAs in view of Ge and it goes like this: (31 + 33)/2 = 32 or, in chemical logic symbols: (Ga + As)/2 = Ge.

Like gallium arsenide, germanium is a photovoltaic material. Google "germanium solar cell" and you will find cutting edge research involving blends of gallium arsenide with germanium. I'm glad there is on-going research into new materials because I am not sure we should be putting arsenic on every rooftop much like we're putting mercury in every lightbulb.

A similar "bookend relation" occurs a couple rows up in the Table between boron, carbon, and nitrogen. Look how boron and nitrogen bracket carbon:

Once again, (5 + 7)/2 = 6. And just like carbon, boron nitride (BN) has both graphite- and diamond-like structures. One type of BN is even harder than diamonds: link

I see a pattern here: the centrality of the carbon group, C, Si, Ge, etc. to the family of main group elements:

What Is The World's Smelliest Chemical?

Wikipedia corrals some of the suspects here: link  I thought I'd put their mugshots up here. Please vote for your favorite in the comments or suggest your own "worst."

(1) Spermidine, the essence of "funky spunk." 

Spermidine is related to aptly-named cadaverine and putrescine.

(2) Trimethylamine, the essence of "fish taco:"

(3) Butyric Acid, the essence of vomit:

(4) Skatole, an indole & the essence of poop:

(5) Mercaptans--methyl and butyl thiols--the essence of skunk:

R = methyl and butyl

(6) Hydrogen sulfide, H₂S, the essence of rotten eggs and bad farts:

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Runner's up which did not make Wiki's list:
(a) Cacodyl, named from the Greek, meaning "evil-smelling."
(b) Bromine, from Greek βρῶμος, brómos, meaning "stench (of he-goats)"
(c) Cyclohexane thiol: This is technically covered under (5), but to my nose smells like the essence of armpit B.O.

Americans Out-Sequester The World In Carbon

I've come up with a simple formula that allows converting body weight to the corresponding weight of dry ice (CO₂) sequestered by an individual. The magic factor is an astonishingly simple factor of 2/3. The conversion factor is irrespective of weight units (lbs or kilos). I derived the number as follows:

The human body contains 18% carbon by weight, meaning that 100 pounds of body weight contains 18 pounds of carbon.  To convert to corresponding pounds of carbon dioxide, I multiplied by a factor corresponding to the increase in mass when carbon "burns" to carbon dioxide = [12 + 16 + 16]/12 = 3.67*  This is also just the molecular weight ratio of CO₂ to carbon.

These two factors, .18 x 3.67 = 0.66, which is very close to 2/3.  That factor, (2/3) multiplied by body weight, gives the corresponding weight of a block of CO₂ which all the carbon sequestered in a body would form.

So how much carbon do American adults sequester en mass? The average American male weighs about 190 lbs and the average American female weighs about 150 lbs. Using a 50/50 ratio for males to females and figuring that about 80 % of Americans are aged 15 and up (i.e., neglecting children), I estimate the total amount of carbon dioxide sequestered by the American adult population of 307 M people as follows:

307 M x .80 = 245 million adults. It follows that American men sequester:

245 M/2 x 190 x 2/3 /2000 = 7.8 M tons of CO₂; and

American women sequester:
245 M/2 x 150 x 2/3 /2000 = 6.1 M tons of CO₂. I converted from pounds to tons using the factor 2000 lbs = 1 ton.

American adults sequester approximately 14 million tons of carbon dioxide. That's got to be on par with a decent-sized forest. Note that men sequester more than women because they are heavier and have more carbon.  Obviously Americans -- considered the heaviest of humans -- sequester the most carbon per capita worldwide.

OK, have at it!
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*Lavoisier famously showed that metals increase their mass when they burn to their oxides, thus destroying phlogiston theory. I'm showing the same thing here by considering carbon to be like a metal and carbon dioxide to be like a metal oxide.

The Very First Guinea Pig?

Commenter Ritmo's link to the wiki article about dioxin mentioned guinea pigs, which reminded me of Lavoisier, who may have been the first scientist to test theories using that animal. Lavoisier famously taught that combustion was the combining of oxygen with other elements, overthrowing the older notion of phlogiston which I wrote about here.

According to the OED of etymology, the first recorded use of the term guinea pig in a scientific context dates from the 1920s. However, the following description of the work of Lavoisier and Laplace clearly antedates that usage: link to original

Lavoisier's respiration experiments invalidated the phlogiston theory despite protestations from Priestley and Scheele. Lavoisier collaborated with French mathematician Pierre Simon de Laplace (1749 -1827) on problems in respiration chemistry. Their vital experiments with guinea pigs in 1780 first quantified the oxygen consumed and carbon dioxide produced by metabolism. Over a ten-hour period, they collected approximately 3 g of carbonic acid from an animal breathing oxygen. In a second experiment, they placed a guinea pig into a wire cage, which in turn was placed into a double-walled container. Ice packed into the double walls of the outer container maintained a constant temperature; ice between the cage and the inner wall of the container melted because of the animal's body heat. During 24 hours 13 oz. (370 g) of ice melted. Lavoisier and Laplace concluded that the total heat produced by the animal equaled the amount heat required to melt ice. In their own words:

Respiration is thus a very slow combustion phenomenon, very similar to that of coal; it is conducted inside the lungs, not giving off light, since the fire matter is absorbed by the humidity of the organs of the lungs. Heat developed by this combustion goes into the blood vessels which pass through the lungs and which subsequently flow into the entire animal body. Thus, air that we breathe is used to conserve our bodies in two fashions: it removes from the blood fixed air, which can be very harmful when abundant; and heat which enters our lungs from this phenomenon replaces the heat lost in the atmosphere and from surrounding bodies.
...animal heat conservation is thus largely attributable to heat produced by the combination of humid air inspired by the animals and dry air in the blood vessels.

Lavoisier's ideas were radical for 1780 because they connected heat, work, and energy.

Conversations with Henry: I'm Your Hapten

[This post is a continuation-in-part of the previous post]

Henry: What Wilkinson first gave the world now goes by a name. It's called hapticity.

Me: I know what hapticity is, but I didn't realize the word was Cotton's idea.

Henry: Yep.  Cotton was Geoff Wilkinson's first student.

Me: Did you know him?

Henry: Of course! Both of them.

[pause]

Henry:  I suppose the notion was there all along, sort of half-baked.

Me: What was?

Henry: Hapticity-the notion that a metal could latch onto several carbons simultaneously.  I mean, there was Zeise's salt, known since the 1820's, yet nobody knew its structure. That sure changed quickly.  Then along came Dewar and Chatt, your heroes, to explain it all! [Henry laughs]

Me:  They're not my heroes! Well maybe Dewar was.

Henry: And then there was Reihlen's iron butadiene complex. That was like an open-faced sandwich! [Henry laughs again]. Geoff knew all his work too--even though the war hid some of it. It still does.

Me: You make it all sound so obvious!

Henry:  No, Geoff just proved Pasteur's old dictum that chance favors the prepared mind.

Irony

Iron has so much history that I may have to make a little hash tag label for it like I did for carbon with bloghetti carbonara. There is just too much for one blog post.

In my last year in college at Madison, I took a graduate level course (Chem 714) called Organometallic Chemistry of the Transition Elements. I may have been the only undergraduate in the course. One of the reading assignments was called "The Iron Sandwich. A Recollection Of The First Four Months" by Geoffrey Wilkinson (Journal of Organometallic Chemistry 1975, 100, 273-278).

Wilkinson narrates the story of how he deduced the correct structure of ferrocene, shortly after its incorrect structure was first published. The work was seminal and led (in part) to his sharing the 1973 Nobel Prize in Chemistry along with E. O. Fischer of Munich.

Here he sets the stage (annoying footnotes are mine):

In early September of 1951, I arrived at 12 Oxford Street, Cambridge, Mass., as a new Assistant Professor in the Harvard Chemistry Department. I owed my appointment largely to my nuclear background. Harvard had originally intended to appoint a tenure member in nuclear chemistry, a plan which did not materialize, and had settled for myself and an Instructor, Dick Diamond, a newly graduated Ph.D. from Seaborg's laboratory in Berkeley. I was given a laboratory in the Mallinkrodt Laboratory, and went to work collecting chemicals and apparatus and built myself a small vacuum line.*

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* By vacuum line, Wilkinson means a glass tube contraption having numerous valves and fittings designed to allow working in the absence of air. Organometallic chemistry included many interesting chemical species which reacted with atmospheric oxygen- see for example the contemporaneous catalysts Ziegler was exploring an ocean away.

Wilkinson went on to describe adjusting to Harvard faculty life in a chatty way before focusing on his eureka moment:

So the story for me actually began on Friday, I think 30th January, 1952. I normally went into the Departmental Library lateish on Friday afternoons, and as usual I picked up Nature, in which I found the celebrated note by Kealy and Pauson.*  On seeing the structure...I can remember immediately saying to myself  "Jesus Christ it can't be that!"

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*T.J. Kealy and P.L. Pauson, Nature, 168 (1951) p. 1039.

Wilkinson intuited that the published structure was wrong because it was inconsistent with any other existing iron compound. The published structure (above) implied that a central iron latched onto just one carbon of each five-sided carbon ring (cyclopentadienyl). In a flash of insight, Wilkinson immediately sketched what was later redrafted for publication as:

He proposed the two hourglass-shaped structures differing only in how the five-sided rings (the bread slices of the iron sandwich) aligned with each other. He quickly went on to show that other sandwich structures existed for other metals, discovering a new genus of compounds now generically called metallocenes.

One irony in this story is that Harvard failed to offer Wilkinson tenure after he did this prize-worthy work, despite the widespread acclaim it engendered during his time there.  Harvard either didn't recognize the importance of his work or, as I suspect, he made some academic enemies there.

I recently found myself at an informal meeting of chemists and a story regarding Harvard Chemistry came up: "Yeah, Harvard--they never tenure anybody" a friend said.  After sixty years, they haven't shaken that reputation. To many, Harvard broke the code of not rewarding merit.

Wilkinson's subsequent career certainly didn't suffer.  He went on to chair the Department at Imperial College in London. He wrote an outstanding textbook used by generations of chemists. He discovered "Wilkinson's catalyst" (something that became near and dear to me).

The tenure story gets better when Harvard's Robert Burns Woodward is considered. Woodward is a co-author on the original ferrocene paper with Wilkinson but did not share that prize with Wilkinson. Woodward, perhaps the greatest American organic chemist ever, had previously won a Nobel Prize alone and probably would have shared another--had he lived--but not this one. Wilkinson thought that Woodward had had the same flash of insight as he. But did he? You can read the story for yourself here,* retold by Professor Roald Hoffmann of Cornell University.  Hoffmann knew Woodward. They shared a Nobel Prize together. But that's another story worthy of bloghetti carbonara.
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*Warning: Hoffmann invokes Rashomon, and quite aptly I think.

Blessed Are The Wealth Makers

Wallace Hume Carothers (1896-1937)

DuPont made a fortune selling things like gunpowder and nitrocellulose to warring governments (mainly to our own) up through and including the First World War. During the roaring 1920s (and flush with cash before the crash) they decided to pursue pure research into material science and established a new division at their fledgling Experimental Station located near Wilmington, Delaware.

The company hired a young PhD chemist named Wallace Carothers to start up a new group. Carothers was fascinated by long chain macromolecules ubiquitous in nature but which had only recently been recognized as "polymers." With the exception of Bakelite, the first synthetic plastic,* other synthetic polymers were unheard of, let alone commercially successful.

DuPont's research gamble paid off and Carothers and his group brought the company enormous success, first with the serendipitous discovery of neoprene, the first synthetic rubber, and then with nylon. Neoprene and nylon were tangible wealth creation: making things of value from what were, at the time, essentially waste products.

Nylon was Carothers' baby. Not only did he invent a synthetic replacement for silk, he purposefully developed a new method of making polymers called step-growth polymerization. He used the same durable type of linkages used by proteins (amide bonds), mimicking nature. Nylon was the first synthetic fabric and was commercialized around 1938, just in time to replace Asian silk which, along with natural rubber, went missing during the Second World War.

We have a lot to thank Carothers for but he didn't stick around. He checked out early, killing himself in 1937.
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* I have two items made from Bakelite: One is a late 1940's era Viewmaster device and the other is my father's old Kit-Cat clock which I described here. Both of these items have the characteristic fragility and tendency to chip common to Bakelite.

Meet the Priest who invented Flubber

Remember the storyline from Walt Disney's The Absent Minded Professor(1961)?  Fred MacMurray played a small Midwestern college chemistry professor who invented a miraculous substance which he named Flubber. He saved the football team and got the girl in the end. I think I found the real-life embodiment-well, forget the getting the girl part and focus on the chemistry and small midwestern university parts.

Reverend Julius Nieuwland (1878-1936)

I ran across the name Julius Nieuwland recently. Nieuwland was a priest and professor at Notre Dame University. As part of his Ph.D research, Nieuwland discovered Lewisite which was produced in tonnage quantitites by the U.S. during World War I as a poison gas.  Nieuwland had nothing to do with this application and distanced himself from the molecule (it's named for an enthusiastic supporter of gas warfare, named Lewis). Later, as a professor of organic chemistry at Notre Dame, Nieuwland successfully polymerized acetylene into divinylacetylene, laying the groundwork for the discovery of neoprene by Du Pont.

One of Nieuwland's more famous students was Knute Rockne, which even explains the football part of the otherwise bizarre Flubber story.

How Titanium Gets All Touchy-Feely with Carbon

A titanium chloride catalyst holds one end of the growing polymer chain. The same titanium atom simultaneously binds another incoming ethylene and stabilizes the contortions leading to the insertion of the next link into the growing chain. Titanium does this by polarizing ethylene's electrons while stabilizing a migration:



Original is here


Polarization, followed by attack, followed by depolarization...polarization, followed by attack, followed by depolarization...polarization, followed by attack, followed by depolarization... link

Ethylene, Daughter of Ethyl

Factoid for the day:

In the mid-19th century, the suffix -ene (an Ancient Greek root added to the end of female names meaning "daughter of") was widely used to refer to a molecule or part thereof that contained one fewer hydrogen atoms than the molecule being modified. Thus, ethylene (C₂H₄) was the "daughter of ethyl" (C₂H₅). The name ethylene was used in this sense as early as 1852. Wiki link

I could blog all day about ethylene, but that factoid was something I didn't know until today. Ethyl has lots of sisters too like Propyl, Butyl (one of the But-sisters), and Pentyl, etc.

Ethylene is ready for her close-up now: