Early readers will remember that one of my favorite things about artificial sweeteners is that they seem to often be discovered by accident. Apparently acesulfame is no exception:

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I’ll admit it - sometimes, when I have no idea what molecule to write up, I’ll look at the American Chemical Society’s Molecule of the Week Page. And sometimes I pick the one with a name that makes me smirk. Enter zingerone:

The name is easily dissected. Zingerone is a natural product from ginger. “Zinger” is ostensibly from the ineffable zest associated with ginger. “-one” is the suffix associated with the functional group known as a ketone.

As the ACS page notes, zingerone shares some common structural characteristics with capsaicin and vanillin:

Thinking like enters into it when a chemist looks at the structure and metabolic pathways leading to chemicals that plants make. The really weird stuff always seems to come from plants. There is a whole subfield of chemistry known as natural products chemistry devoted to studying this stuff. Plants, you see, are distinctly lacking in legs, fangs, claws, and guns, and they have had to make do with some (often strikingly toxic) chemical defenses. You see it in sea life, too, as in the case of fugu’s tetrodotoxin.

Vanillin (and I’d guess the other “vanillinoids”, but I’m not sure), are synthesized from two closely related amino acids, phenylalanine and tyrosine. As naturally occuring amino acids, they are ubiquitous, and find their way into all sorts of structures (since they’re relatively “cheap” to use).

Have a good weekend.

Esters are a continuing source of fascination for me. Chemically, they’re unremarkable. If you heat an alcohol and carboxylic acid together under conditions that allow it to eliminate water (say, by doing the reaction in the alcohol or acid under concern, if one’s liquid), they will form a compound called an ester. Usually you add a trace of additional acid as a catalyst - a drop of hydrochloric acid solution is common.

What’s remarkable, though, is the smell. Pentanol (amyl alcohol, in old-school chemspeak, rarely used, but I learned this ester as “amyl butyrate”) is unremarkable, and it smells like most low-molecular weight alcohols - a bit like ethanol, a bit like lighter fluid. Butyric acid, however, is Satan’s own carboxylic acid - it is a sort of B.O./vomit/Sex Panther odor. Read the rest of this entry »

Dihydroxyacetone is a very, very simple sugar. It is produced by the splitting of hexoses (glucose and fructose) in glycolysis. Most people are interested in it, though, for its role in sunless tanners:

Many sugars, DHA included, can participate in a reaction called the Maillard reaction. In this reaction, sugars react with amino acids and proteins. This can result in brown pigments. DHA (sugar) reacts with skin proteins (amino acids/proteins), providing a rich brown pigment, if you’re lucky, or an orange pigment, if you’re not.

The same reaction responsible for sunless tanning results in meat browning (and flavor). Bizzare.

Night!

Here’s a quickie, phenolphthalein:

Phenolphthalein is known as an acid-base indicator because it gives a colorimetric change depending on the pH. Above a certain critical pH, called its pKa, phenolphthalein adopts mainly the lower structure shown above . Below this pH, it is mainly the upper structure. The lower structure is pinkish-purple, the upper is colorless.

As you can imagine, molecules like this have all sorts of uses. You can figure out the concentration of an acid or base, using the color as an indicator of whether your solution is acidic or basic (8.2 is sufficiently close to 7, neutral pH, that you can get away with this). It apparently is used to test for the presence of blood. It used to be used as a laxative, but its carcinogenicity has not been completely ruled out. It is also used in Barbie Hollywood Hair (scroll down to “uses”).

The broad class of dyes are used in “pH papers” for lab use; papers soaked with one or more dyes will change color depending on the pH; a series of dyes can give resolution below even 1 pH unit, which is pretty good. “Litmus” paper is the best known of these, containing a dye extracted from lichen.

You can extract your own pH indicator from cabbage. If you never did this, you had a deprived childhood and should try it over the weekend. If you are lazy, you can just use red wine or grape juice; there is a similar pigment with red acidic and blue basic forms. This broad class of pigments is known as anthocyanins. Many of the deep reds and blues in nature are due to this class of pigments, and they make great pH indicators.

Today’s molecule, canthaxanthin, is a member of the carotenoid family. This includes beta-carotene and lutein. These molecules are all strongly colored. This is a function of the degree of conjugation in the system.

A conjugated system has alternating double and single bonds, as you see in that long central chain. Small conjugated systems like benzene absorb in the UV, and larger conjugated systems, like our carotenes, absorb lower-energy light, yielding a visible color. For more information, see particle in a box (warning to the uninitiated: this ventures into quantum mechanics and gets a bit esoteric). Read the rest of this entry »

This one is obvious. It smells like, well, vanilla. Exactly like vanilla. Some people claim that it is a simplistic, cloying version of vanilla and you should always buy real vanilla extract instead of synthetic (which is mostly vanillin); I say these people are exaggerating. While you can definitely smell a difference, vanillin gets you 95% of the way there, and it isn’t a one-note wonder. If the smell weren’t so ubiquitous we’d find it much more amazing. Earthy and rich, yet spicy and vibrant, it really is a singular aroma. Read the rest of this entry »

I’ve mentioned this in the past as one of the canonical bitter compounds. It was originally extracted from the bark of the cinchona tree. It has been found useful in the treatment of malaria. The scope of malaria’s effects is both broad and amazing. According to a citation in Wikipedia, malaria infects 350-500M individuals annually - for reference, this is roughly 6-8% of the world! The vast majority of infections are in African children.

Antimalarial drugs, then, are a godsend. One of the most famous natural products ever, quinine was extracted from cinchona for years, and finally synthesized by Bob Woodward in 1944. The pharmaceutical and chemical industry would look incredibly different today if this man had never existed. You can see a picture of him at Dylan’s Tenderblog. He is the one on the right, smoking the cigarette next to the flask of the toxic and/or flammable chemicals. Amazingly, RB Woodward’s total synthesis of quinine takes up only one page in a journal. It would be slightly longer today. With more pictures. Here’s a picture:

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Sorry to punt again but I’m just getting home. Today’s molecule is carboxymethylcellulose. It is made from cellulose by its reaction with chloroacetic acid.

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Again, another artificial sweetener discovered by sloppy, sloppy chemists. God bless them (us?). It makes me wonder sometimes whether I’m working with a bench full of delicious chemicals that are just waiting for an accidental taste.

Aspartame was discovered in 1965 by James M. Schlatter, a chemist working for G.D. Searle & Company. Schlatter had synthesized aspartame in the course of producing an anti-ulcer drug candidate. He discovered its sweet taste serendipitously when he licked his finger, which had accidentally become contaminated with aspartame.

Here is the structure of aspartame. It is the methyl ester of a dipeptide of aspartic acid and phenylalanine. That’s it. It’s an incredibly simple structure:

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