Org Prep Daily

October 18, 2011


Filed under: lit highlights — milkshake @ 12:07 am

A remarkable molecule:  Hygroscopic, edible, stable and pleasantly-tasting natural sugar. While keeping foodstuff moist and producing a desirable mouth-feel, trehalose also masks greasy rancid off-flavors like no other food additive. Trehalose inhibits lipid autooxidation by interacting with the C=C bonds of fatty acids. Trehalose has also a stabilizing effect on denaturation-prone proteins. It is an effective cryoprotectant and anti-desiccant for living cells.

Trehalose is widely used as food additive in Japan. (It got classified by FDA recently as ‘generally recognized safe’  so expect trehalose-immortalized pastry snacks at gas stations soon). Two protein-based drugs co-formulated with trehalose are already on the market.

I would like to direct you to a minireview from Dr. Higashiama, a research team leader at the trehalose manufacturer Hayashibara Co. Some important practical applications are discussed in detail:

“In this application, we examined the suppressive effect of trehalose on human body odor. The typical odor of a senior layer (odor from seniors) increases with age, especially 55 years or older. This odor contains unsaturated aldehydes such as 2-nonenal and 2-octenal. These aldehydes are produced by the degradation of unsaturated fatty acid (palmitoleic acid) in aged people’s skin. The subjects (55 years or older) were selected from our company. After a shower, their body was sprayed with a 2 % trehalose solution. They put on new underwear after the spray. Twenty hours later, the unsaturated aldehydes were sampled from the used underwear shown in this system using DNPH-column. The trapped aldehydes were eluted from this column and were analyzed by gas chromatography. The results showed a decrease of about 70 % in odor from seniors due to the action of trehalose (Fig. 7). This result indicates that trehalose has a suppressive effect on the formation of the odor released by the seniors’ bodies. The same results came out with the oxidation of fatty acid. Therefore, the application of trehalose for cosmetic fields is expected.”

T. Higashiama: Pure and Applied Chemistry 74, 1263–1269

(Fig. 8):


  1. Indeed. Trehalose is used by the remarkable tardigrades which can withstand intensely dry and cold conditions. It owes its unusual properties partly to the conformation of some of its hydroxyl groups whose orientation relative to glucose renders the molecule more hydrophobic.

    Comment by Curious Wavefunction — October 18, 2011 @ 7:30 am

  2. Could we spray old people with copper to see if it makes them more stinky?

    Comment by Honclbrif — October 18, 2011 @ 6:36 pm

  3. Nice, information on Trehalose. In-fact I did not hear about it before till i came across your post. You mentioned that it could decrease/ suppress the production of stink factors from the body of seniors. It is a good sign to act as a deodorant. But begin a pharmacologist I am concerned about the side effects it can induce due to its suppression effect. Thanks.

    Comment by ranganr — October 19, 2011 @ 2:31 am

  4. Ig Nobel Committee – are you listening?! GCMS on the elderly. #winning

    Comment by DrFreddy — October 22, 2011 @ 3:26 pm

    • I especially liked that they sprayed their senior employees with a sticky sugar solution and forced them to wear it for 20 hours. And they confiscated their undies twice (before and after) and put it through a battery of tests to precisely determine how much their employee smelliness has diminished.

      Comment by milkshake — October 22, 2011 @ 5:53 pm

      • Oh yeah, I can just imagine the company meeting: OK guys, anyone over 50, trousers down and in the shower!

        Comment by =8)-DX — October 24, 2011 @ 9:55 am

  5. The experiment would only be carried out correctly if the seniors were checked during and after their shower for effective cleanliness…

    Just a thought, just a thought.

    Comment by Jos Pros — October 27, 2011 @ 9:11 am

  6. “…the unsaturated aldehydes were sampled from the used underwear….”

    This is a phrase I have been waiting all my professional life to use.

    Comment by RB Woodweird — October 28, 2011 @ 2:49 pm

  7. I knew caproic acid was responsible for “old goat smell” but now I know what’s responsible for “old person smell” : 2-octenal and 2-nonenal. By the way did you know that octanal is responsible for the smell of “stinky giraffe”? Now you do.

    Comment by James — October 30, 2011 @ 10:49 pm

  8. These days there’s a lingering “man-who-hasn’t-bathed-in-6-days” smell in my lab. Someone’s been running Sandmeyer brominations using isoamyl nitrite followed by CuBr2, and the residual isoamyl alcohol seems to be everywhere. Vapours stuck “within” the balance, so whenever you open these balance doors, hope you’re not hungover, for you’ll puke. For sure.

    Oh, and I pity the poor guy running these 25g runs… the workup appears to be tediously godawful!!!

    Comment by HPCC — October 31, 2011 @ 9:06 pm

    • it is not actually smell of isoamyl alcohol but isovaleric acid (which has much richer reek than butyric acid): isoamyl nitrite slowly decomposes and the impurities include isoamyl aldehyde and isovaleric acid. To purify the old stinky batch one needs to wash it with bicarbonate before re-distillation (the acid impurities catalyse further decomposition on heating). I actually much prefer to use tBuONO, the comercial product has a reasonably good stability on storage. Also the prep procedure for n-Bu and isoamyl nitrite is very simple, sometimes it is worth to make your own rather than to purify an old batch.

      Comment by milkshake — November 1, 2011 @ 11:07 am

      • I’ve got a fun history with isovaleric acid. Back in my sophomore organic chem lab, during the ester synthesis experiment, I chose isovaleric as my acid. I did not know what I was in for. Suffice to say, one poorly constructed distillation rig later and I was saturated with it. I threw out my clothes, but it had soaked into my hands and I was a pariah for about three days before the stuff totally washed out (just ahead of my remaining skin). Luckily my room mate was incredibly understanding for an English major.

        Later in my research career, I did a reaction which made some isovaleric anhydride as a byproduct and the stuff smells fantastic! Deliciously fruity with warm almost nutty-chocolatey undertones. I’m still planning a lab prank around the stuff and a slow hydrolysis.

        Comment by Honclbrif — November 1, 2011 @ 4:41 pm

        • you can do the prank with isovalerate esters – methyl or ethyl will do. They have a very nice fruity flavor so unsuspecting victim might be convinced to put some on their skin, whereon it gradually hydrolyzes. This prank was done to me in elementary school, in a chemistry club, by some evil kid from a competing group

          Comment by milkshake — November 1, 2011 @ 5:32 pm

  9. Query:

    To form chloroimine compounds from amides, POCl3 is the reagent of the choice. Do we require stoichiometric quantity of POCl3 or 1/3 eq of PoCl3. Majority of the research publication go with large excess of POCl3 and it is documenetd that only one chlorine is delivered to product from POCl3. and the by-product PO2CL2 gets destroyed during the work up. But there are couple of patent lit where 0.7 to 0.8 eq of POCl3 is used. Also few protocols use tertiary amine in substoichiometric amounts to drive the reaction. I dont understand this. Your clarification in this regard is highly appreciated.


    Comment by pasupathy — December 6, 2011 @ 1:50 am

    • In the past I was always employing an excess of POCl3 for this kind of reaction so I don’t know. Possibly you could utilise the second equivalent of Cl under some more forcing conditions… By the way PCl5 is a lot more powerful reagent for this kind of reaction and the sideproduct is a POCl3 so there you could definitely use half-equivalent amount

      Comment by milkshake — December 6, 2011 @ 2:39 pm

  10. Interesting data. Unfortunately, all the >55 year old employees in the US pharma industry have been layed off due to drug expirations, and these experimental trials could not be confirmed. Likewise the remain three pentagenerians employeed by US Pharma are so scared of being layed off that their underwear have other strong odors eminating so that they would mask the less fragrant olefactory eminations of the long chain aldehydes.

    Comment by ROGI — February 8, 2012 @ 10:51 pm

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