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Hightech Redneck

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    Hey everyone, hope you are all doing well! I just wanted to drop in and see if anyone had any questions for me?
    Hope you are well, once you get past the Panthers start this season lol.
    I tagged you in another thread in regards to seed steeping, curious about your thoughts. Did you see that?
     

    The_Vapin_Chemist

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      Hope you are well, once you get past the Panthers start this season lol.
      I tagged you in another thread in regards to seed steeping, curious about your thoughts. Did you see that?
      Yes, I am quite depressed about the the start we have had, but I think DA will get us back on track this week.

      I did see where you tagged me, but I wasn't sure on the rules whether I was allowed to respond in that thread. So my best educated guess is seeding speeds the equilibrium shift essentially. So reactions has an equilibrium where you still have some amount of starting product and some amount of final product and some intermediate products in between (usually). So my thought is that by adding some of the already steeped juice, you are supplying some of the intermediate products that may be needed for the reaction and some of the final products to help pull the reaction towards equilibrium.
       

      O.G.

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        So I made an account to ask a relatively scientific question regarding wintergreen flavor. I can't find anything related to this topic (including scholarly articles) and was hoping for some feedback from someone knowledgeable in chemistry.


        Methyl Salicylate is a METHYL ESTER. This means that it can (under the right conditions) decompose into methanol and salicylic acid through hydrolysis. Typically, it is used in very low concentrations as a flavoring due to its relatively high inherent toxicity (LD50=0.5g/kg), and is typically not subject to heating when consumed, or added in the presence of an acid/base catalyst.


        My question is; wouldn't methyl salicylate (aka wintergreen) be susceptible to hydrolysis under the elevated temperature, not to mention weakly basic conditions found in an e-cigarette, and therefore be TOXIC due to the methanol it would produce. Even if the quantity produced is very small, this would still have toxic effects as methanol is EXTREMELY poisonous.


        This process does require water to be present you may argue! but I remind you there is water in the air flowing through your atty, not to mention the water added to liquid by some venders…AND the fact that nicotine is a weak base and may assist in catalyzing this reaction!


        Let me know what you think! For now, I’m not touching those wintergreen flavours.


        O.G.
         

        Hitmetwice

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          Hey O.G. welcome to ECF firstly. I know I'm not the guy you're looking for an answer from and I am likely way off base, but "natural" wintergreen is most likely where the problems would originate. Synthetic or man made "wintergreen flavouring" may be able to be made without these compounds.

          Only guessing tho, I'm looking forward to an informed reply myself. Cheers.
           

          The_Vapin_Chemist

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            So I made an account to ask a relatively scientific question regarding wintergreen flavor. I can't find anything related to this topic (including scholarly articles) and was hoping for some feedback from someone knowledgeable in chemistry.


            Methyl Salicylate is a METHYL ESTER. This means that it can (under the right conditions) decompose into methanol and salicylic acid through hydrolysis. Typically, it is used in very low concentrations as a flavoring due to its relatively high inherent toxicity (LD50=0.5g/kg), and is typically not subject to heating when consumed, or added in the presence of an acid/base catalyst.


            My question is; wouldn't methyl salicylate (aka wintergreen) be susceptible to hydrolysis under the elevated temperature, not to mention weakly basic conditions found in an e-cigarette, and therefore be TOXIC due to the methanol it would produce. Even if the quantity produced is very small, this would still have toxic effects as methanol is EXTREMELY poisonous.


            This process does require water to be present you may argue! but I remind you there is water in the air flowing through your atty, not to mention the water added to liquid by some venders…AND the fact that nicotine is a weak base and may assist in catalyzing this reaction!


            Let me know what you think! For now, I’m not touching those wintergreen flavours.


            O.G.
            From the information on Pubmed, I gather that there is no concern for a reaction with the nicotine. It reacts with Strong Oxidants and Bases, but nicotine is a rather weak base. Also, for the most part, methyl salicylate is a relatively stable molecule and was evaluated by the Joint FAO/WHO expert committee on Food Additives in 2001 to have no safety concerns when used at 0.5mg/kg by weight. The flavor manufactures themselves know more than these chemicals and the safety requirement by FEMA and the like than I do. If you have concerns about their safety and can live without wintergreen in your e-juice then I would advise to stay away from them. "I'd rather be safe than sorry", as they say.
             

            O.G.

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              Hey The Vapin Chemist,

              Thanks for replying! I would not be concerned with it reacting with nicotine, or its thermal decomposition, just the following reaction:

              Methyl salicylate + H2O ------> Methanol + Salicylic acid

              Base

              It's the hydrolysis reaction I am concerned about; it's a typical method used to cleave esters into their components.

              Even if this reaction occurs to a minor extent, the presence of a few PPM of methanol may actually cause some nasty effects over time. As far as I can see (and I'm sure you did some research) there is no data regarding these particular conditions. You are definitely right regarding the "better safe than sorry" approach, though I hope I’m not the only skeptical one in this case!
               
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              The_Vapin_Chemist

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                Hey The Vapin Chemist,

                Thanks for replying! I would not be concerned with it reacting with nicotine, or its thermal decomposition, just the following reaction:

                Methyl salicylate + H2O ------> Methanol + Salicylic acid

                Base

                It's the hydrolysis reaction I am concerned about; it's a typical method used to cleave esters into their components.

                Even if this reaction occurs to a minor extent, the presence of a few PPM of methanol may actually cause some nasty effects over time. As far as I can see (and I'm sure you did some research) there is no data regarding these particular conditions. You are definitely right regarding the "better safe than sorry" approach, though I hope I’m not the only skeptical one in this case!
                Yes, if a vendor were to add water to the e-juice, this is feasible. However, there are a couple of problems.
                1) Mint flavors such as wintergreen, spearmint, menthol, etc. crystalize in the presence of water and are pretty much un-vapable.
                2) This is an equilibrium reaction, so the reaction would never go completely to one side.
                3) The standard catalyst for a esterification reaction is sulfuric acid (a very, very strong acid) and you will find no such acid or base in e-juice to catalyze this reaction.
                 

                O.G.

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                  Hey again The Vapin Chemist!


                  I do agree with some of those points, though I don’t see any way of evaluating the extent of this reaction without doing a study involving some sensitive analytical method (GC/FID, MS etc.).


                  1) Menthol and (R)-carvone do have trouble dissolving in water and are usually used in very small concentrations to get around forming suspensions. I personally have used spearmint ((R)-carvone) at a concentration of about 100 ppm with no problems, anything over that turns cloudy. The solubility in water would be similar to PG and VG as both are hydrophilic (not the same though). Methyl salicylate is much more soluble though! (water solubility is MUCH higher; 0.639 g/L (21 °C) *from wiki*)

                  2) The equilibrium is the main reason that I would think this wouldn’t happen to a very large extent because the serious lack of water (even if venders don’t put water in, it will still be present in the air flowing through the atty). BUT the entropy for this reaction would be around 0, so the enthalpy term would take over determining where the reaction lies and would be favorable at any temperature ( it is exothermic) as long as the entropy term isn't positive!

                  3) Yes, the esterification and hydrolysis reactions both do typically use a strong acid or base BUT from my research and studies I am under the impression that this reaction does proceed with no catalyst but to such a minor extent it is useless as a synthetic method.
                   
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                  The_Vapin_Chemist

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                    Hey again The Vapin Chemist!


                    I do agree with some of those points, though I don’t see any way of evaluating the extent of this reaction without doing a study involving some sanative analytical method (GC/FID, MS etc.).


                    1) Menthol and (R)-carvone do have trouble dissolving in water and are usually used in very small concentrations to get around forming suspensions. I personally have used spearmint ((R)-carvone) at a concentration of about 100 ppm with no problems, anything over than that turns cloudy. The solubility in water would be similar to PG and VG as both are hydrophilic (not the same though).

                    2) The equilibrium is the main reason that I would think this wouldn’t happen to a very large extent because the serious lack of water (even if venders don’t put water in, is it still present in the air flowing through the atty). BUT the entropy for this reaction would be around 0, so the enthalpy term would take over determining where the reaction lies and would be favorable at any temperature as long as the entropy term isn't positive!

                    3) Yes, the esterification and hydrolysis reactions both do typically use a strong acid or base BUT from my research and studies I am under the impression that this reaction does proceed with no catalyst but to such a minor extent it is useless as a synthetic method.
                    I agree that to some extent this reaction definitely could occur in solution and this needs some real in-lab experimentation. I am just pointing out some possible hiccups.
                     

                    DC2

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                      I've been following this thread but didn't think I had anything important to post.

                      But the latest conversations have me thinking that I just might have a question here.
                      So here is where I originally posted it, and hoping you could take a look...
                      Anyone have problems vaping menthol?

                      Thanks!
                      DC2
                       

                      O.G.

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                        As far as I know menthol would be safe to inhale at concentrations intended to be used as flavor:

                        Does inhaling menthol affect nasal patency or cough? - PubMed - NCBI

                        The study was looking at the effects of menthol on cough, but illustrates how extensively it has been used through inhalation.

                        There are a number of things I suspect, but it would be impossible to tell for certain without further information.

                        1. The obvious one would be the vendor putting other substances into the mix other than menthol. Maybe the "menthol concentrate" they used was ethanol based instead of PG...or maybe some other emulsifying agent.

                        2. I exhausted all my scientific references trying to find the exact or predicted solubility of menthol in PG with no luck. But according to accounts on this form, it is apparently quite soluble in it! This means that the vendor could have put too much of it the liquid, which could give it a heavy feeling due to the excess menthol that may come out of solution when you vape it.

                        3. Along the same lines as #2, but that particular juice you bought may have been meant for mixing into other juices; a concentrated extract that may have been mistaken for prepared e-liquid; iv had a friend do that once.
                         
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                        The_Vapin_Chemist

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                          I've been following this thread but didn't think I had anything important to post.

                          But the latest conversations have me thinking that I just might have a question here.
                          So here is where I originally posted it, and hoping you could take a look...
                          Anyone have problems vaping menthol?

                          Thanks!
                          DC2
                          Yes, @O.G. is correct that menthol is safe to be inhaled. Menthol is used in many everyday products that we use and inhale. To name a few: ICYHOT, Vick's Vapor Rub, essential oils that are used with humidifiers, shampoos, etc. In fact, often menthol is used in much higher concentrations in these products (as much as 5-10%) than we use in vaping.

                          It could be that you just have a sensitivity to menthol or your lungs just became irritated from the intense cold from the menthol. As for the extra coughing, I would probably attribute that to the cold. We cough more in the winter because of the cold, brisk air. I'm not sure why exactly, but then again I'm not a biologist or doctor. :)
                           

                          The_Vapin_Chemist

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                            Hey VC, have you seen the video on ECF with the testing done on lung tissue and menthol? The live cells died when exposed. It is true that they will regenerate but, I still avoid menthol. Just my :2c:
                            I have not seen that, but I will try to find it and give it a watch today if I can find some time. I was just going off of the fact that it is used in some pretty high concentrations (compared to vaping use) in everyday product that we breath in.
                             
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