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I've heard the claim that "Margarine is only one molecule away from being plastic" several times. Usually from friends who think they've heard it from some reliable source. I've also read a couple books that mention this concept, without really addressing its validity.

Is there any truth to this claim?

EDIT

Updating with this claim, as found recently on facebook:

And here's the most disturbing fact... HERE IS THE PART THAT IS VERY INTERESTING!

Margarine is but ONE MOLECULE away from being PLASTIC... and shares 27 ingredients with PAINT.

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It should be, put a slab of it in your garage, insects won't eat it and it will still be there a year later. Possibly the worst substance a person could eat. Take any natural oil or Fat and attach a hydrogen molecule to the oil molecules and you have margarine....en.wikipedia.org/wiki/Margarine#Manufacture –  Moab Sep 25 '11 at 5:31
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Is it possible that the original claim was meant to be "one ATOM away from plastic"? This would almost make sense since both can be produced from oils. Not that it matters if it is true or not. –  John Rhoades Sep 26 '11 at 14:54
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Heck, water is one atom away from pure hydrogen. So careful turning on that faucet, or you might blow up your house. –  Kyralessa Oct 4 '11 at 1:25
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Snopes has weighed in. –  Oddthinking Mar 10 '13 at 7:11
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@Kyralessa: I was just going to say, water is one molecule away from being a bleaching agent! So be careful, you're almost drinking bleach! –  Chinmay Kanchi Aug 1 '13 at 6:26
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2 Answers

up vote 21 down vote accepted

It's a bit of a confused claim.

First, what is a "molecule"?

A molecule is an electrically neutral group of at least two atoms held together by covalent chemical bonds. Molecules are distinguished from ions by their electrical charge. However, in quantum physics, organic chemistry, and biochemistry, the term molecule is often used less strictly and applied to polyatomic ions.

[Source: Wikipedia]

Note: We are talking organic chemistry here. Basically, a group of atoms bonded together.

Now, what is "plastic"?

A plastic material is any of a wide range of synthetic or semi-synthetic organic solids used in the manufacture of industrial products. Plastics are typically polymers of high molecular mass, and may contain other substances to improve performance and/or reduce production costs. Monomers of plastic are either natural or synthetic organic compounds.

[Source: Wikipedia]

So, there isn't one single type of plastic - and typically they are made of huge molecules. My high school chemistry teacher claimed a plastic ice-cream container was in fact a single molecule, due to all the cross-linked bonds between the long chains of atoms.

[UPDATE: This claim has been challenged. See related question. This undermines the forcefulness of the following argument, but doesn't affect its validity.]

So, we can say "Water is one molecule away from being a plastic ice-cream container." or "A vacuum is one molecule away from being a plastic ice-cream container."

Given that, "Margarine is only one molecule away from being plastic" is a confused claim that is both true and does not tell us anything about margarine.

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Just to add: a very common type of plastic is polyethylene which is a macromolecule of ethylene. Sadly, I can't find what is margarine made of (read: I'm lazy), but I have an hard time believing that margarine would be one functional group away (by addition or subtraction) from a large chain of ethylene. –  Borror0 Sep 22 '11 at 3:36
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@Borror0 the main ingredient in most margarines is plant and/or seed oils, like canola or sunflower oil. The canola council of Canada claims Canola oil is 61% oleic acid and 21% linoleic acid. Oleic acid is CH3(CH2)7CH=CH(CH2)7COOH. –  jozzas Sep 22 '11 at 3:41
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Hmmm... I skipped over the last bit of your answer, thinking you were going to say the obvious. I wish I had not because you're wrong. An ice-cream container isn't "one molecule" in any shape or form. Plastic (well, all polymers) are pretty big molecules, but they are not made of a single molecule. Intermolecular links can be very strong (Kevlar, for example, takes part of its strength from hydrogene bonds), but there are many molecules in a plastic container. –  Borror0 Sep 22 '11 at 3:48
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@jozzas: So, if margarine was only oleic acid (for simplicity's sake), then you'd still need to remove the =CH(CH2)7COOH part and then add (CH2)n-CH3 to get polyethylene. That's still "two molecules" away. And also "a confused claim that is both true and does not tell us anything about margarine." –  Borror0 Sep 22 '11 at 3:53
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This claim is as sound as "If you change four letters in 'mama' you get 'beer'". True, but content-free. –  Jens May 12 '12 at 12:42
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The answer is NO, but the question is poorly formed and we have to interpret it to get anything like a reasonable answer

The other answers have already addressed why a simple interpretation of "one molecule away from" doesn't make much chemical sense. But if we generously interpret the intent of the question in a way that makes chemical sense as something like "margarine is made of molecules that are similar to some plastics" we can answer more precisely.

To do so we need to draw some pictures of what typical molecules plastics are made from and what margarines (and butter for that matter) are made from. To avoid excessive clutter in structures chemists draw the carbon skeleton (often omitting the letter C for carbon and trusting readers to fill in the hydrogens so each carbon node has 4 bonds in total). So we draw butanoic acid (CH3CH2CH2COH) as:

butanoic acid structure

Packaging is commonly made of plastics like polyethylene which as a structure like this where n is a large number often in the thousands:

polyethylene

This is probably the one the question likens margarine to, but there are lots of other common plastics. PET (polyethylene terephthalate) is commonly used in packaging (especially soft drink bottles) and looks like this:

PET

Another common plastic used in packaging, cling film and many other uses is PVC which looks like this:

PVC

Only polyethylene bears any resemblance to the constituents of margarine.


So what is margarine made from? Margarine is actually very similar to butter in that it consists of a mixture of natural oils which in turn consist of triglycerides of fatty acids. A typical margarine (see here) might contain a lot of this, for example:

typical margarine triglyceride

Triglycerides are compounds of glycerol and three fatty acids. Fatty acids (which, when separated from the glycerol, are the key constituents of soap) are compounds like this (this is linoleic acid with 18 carbons and two double bonds) with even numbers of carbons from 4 to about 22 in typical plant and animal oils .

linoleic acid

Typical plant oils are liquids at room temperature and people want their spreads to be solids, the plant oils are usually chemically altered a little to create compounds that are solid at room temperature. Since the oils containing fatty acids with multiple CC double bonds are more liquid, food companies use a process called hydrogenation to add hydrogens giving constituents that are solids at room temperature. These are the parts of the margarine that bear a superficial resemblance to polyethylene.

But there are major differences. The fatty acid groups are unlike the simple carbon chains of the polymer because they are terminated with a CO2R group which allows the digestive system to chop up the chain, two carbons at a time, to generate energy. You can't do that with polyethylene as there is no "handle" at the end of the chain for the digestive system to get to grips with. So a superficially small chemical difference makes a huge biological difference. And, of course, the chemical functionality allows the fatty acids to be moved around as the triglycerides (which are nothing like any of the plastics).

Moreover, the carbon chains in fatty acids are rarely longer than 22 carbons whereas polymer chains often have thousands of repeat units. This length alone makes typical polymers biologically inert as they are too insoluble to be digested in normal biological systems (even assuming there was a "handle" for the systems to grip to start the digestive process.)

So despite the superficial resemblance between some plastic polymers and fatty acids, they have little chemical resemblance and the claim that margarine is one molecule away from plastic is nonsense. Moreover, butter, a "natural" product differs from margarine only in having a different mix of fatty acids (it is also mostly made of triglycerides). And some of the fatty acids are essential nutrients for mammals.


Some general references: Some information about fatty acids and triglycerides Typical compositions of butter and margarine Analysis of butter and margarine reference (paywalled)

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