Science topics: Chemistry
Chemistry - Science topic
Chemistry is the science of matter, especially its chemical reactions, but also its composition, structure and properties. Chemistry is concerned with atoms and their interactions with other atoms, and particularly with the properties of chemical bonds.
Questions related to Chemistry
We are living in a world where recently Artificial intelligence is being used in many applications for prediction of many events and things. We all know that the amount and balance of certain Chemicals in the brain have a role in causing us think creative , feel emotional or happy etc. I would like to learn the valuable opinions of Scientists on what specific roles Chemistry would have in creating human conciousness ?
I'm finding some cationic molecules like below.
I tried finding on www.sigmaaldrich.com , but couldn't find anything.
Where can I buy some molecules like this?
ref)Ikeda, Taichi, and Yoshitaka Matsushita. "Tetrahedral Tetra-cationic ionic liquids." Chemistry Letters 49.1 (2020): 14-16.
Salt has an ionic bond. It's chemically bonded. So, when it dissolves in water, the ionic bond is somewhat lost. But, people argue that it is a physical change because-:
a) The mixture of salt and water can be separated by evaporation.
b) No new substance is formed.( how though? isn't salty water completely different from just water or salt alone?)
c) There is no energy produced. (but then again when we tear paper, the ripping creates some energy...so how is there no energy in a physical change?)
Thank you in advance,
I am evaluating the options, especially in the true open-source world, for making reliable calculations with high-accuracy using quantum correlation methods.
I synthesized a molecule. I want to know what are the self-assembled structures possible for it through hydrogen bonding.
If possible, please suggest me some free software available (installation-based or online)
Any relevant suggestions are highly appreciated. Thanks.
Do you have a guess as to which fields and to whom the chemistry and physics Nobel awards will be given this year?
Chemistry question: I've received compounds to dissolve at 10uM. They sent MW, FW, and mg amts for each. Some cpds MW=FW, but others have "salts" added, and those have FW>MW. Should I use MW or FW to convert the mg amt to moles for calculations to achieve uM solutions?
Hello everyone, I have a question about COD (Chemical Oxygen Demand) electrolysis of organic compounds. When doing the COD analysis of the initial sample before treatment, why did it produce a high COD level? what factors in the COD level caused the initial COD level to be very high?
Meanwhile, after being electrolyzed (after treatment), the COD level decreased, what caused the COD level to decrease and were there any structural changes that occurred related to the reagents in the electrolysis process (organic compounds, electrolyte, additional H2O2, COD reagents) .
So, for example, the sample is acetaminophen
Before treatment (acetaminophen + aquades), why was the COD level of the acetaminophen sample so high? what causes the high value? and why after treatment, the COD level of acetaminophen decreased? what causes the COD level of acetaminophen decrease? Are there any structural changes that occur in acetaminophen related to the reagents associated with the electrolysis process after treatment? if there is a change, what kind of change and how?
Thanks in advance.
How can a correlation be obtained from subatomic to superatomic? Why does the subatomic behave differently than the superatomic? Why does something that makes something behave differently from what it creates? Let's give an example to this first: Let's think of H2o water, hydrogen and oxygen: Here, hydrogen and oxygen atoms will behave differently from the water they form. So why is this? Is this due to the change in chemical structure? This means that the change in the chemistry of atoms under matter ensures that matter itself exists on matter. So what provides this? So what is it that changes the chemistry? How is it changing? So why does the thing that brings together this changing chemistry (structure) become matter? If the chemistry changes in the atoms under matter, what do we say if this matter is different from the substance itself, and since the submatter will normally form the above matter logically? If atomic chemistry, that is, subatomic, changes, it becomes supermaterial and they behave differently. Here we reach something: In contrast to atoms, there is something else under matter. In other words, apart from quantum, there is a structure under matter that interacts with atoms under matter and forms the upper part of matter. What should we call this:? Should we call it such a thing that it interacts with atoms and changes their structure and turns them into normal matter? So let it act in classical physics. So what makes atoms move in classical physics? Let's ask this. How do we determine whether something is in quantum or classical physics? If something moves relative to atoms, it's quantum. If there is something directly related to matter itself, it is classical physics. So what is it that differentiates atoms from what is directed directly at matter itself? Let's first explain the quantum theory: An atom could be in more than one place at the same time. So this would mean that an atom cannot be in more than one place at the same time when it interacts and changes chemistry. But what does it do? What kind of thing makes atoms lose this quality? What kind of thing in the universe loses the function of a particle being in two places at once? First of all, let's ask this: Being in two places at the same time;. It means being able to copy yourself and be able to influence at different points. So this thing, the thing that changes the chemistry, must have a function that destroys this quality. What thing in the universe reduces or eliminates influence at different points? What is the most influential thing in the universe? Matter is the answer, which occurs through this space-time warping. So as a result, Isaac Newton's m1.m2/r'2 formula gives us the output. As the distance between the objects increases; gravity (ie, space-time warping), that is, the twist by matter would decrease. In that case, as the distance between matter increases in the universe, the relationship that a substance establishes with submaterial and supermaterial brings us the existence of the supermaterial. Thank you.
In electrofenton, there is one method, namely electrochemical peroxidation, what are the advantages of this method so that it can degrade organic compounds? How is it different from electrocoagulation? what makes electrofenton/electrochemical peroxidation better than electrocoagulation?
Also, there are electrocoagulation and traditional coagulation, what makes electrocoagulation better than traditional coagulation? as well as the electrofenton and traditional fenton, why is the electrofenton better than the traditional fenton? What is the effect of Fe and H2O2 in degrading organic compounds? why when an electric current is applied the results are better? if there is no electricity, is it also good to degrade organic compounds?
Thanks in advance
What parameters play a role in the ability of amines to be protonated in water? Can the base strength of amines be a sufficient measure to compare the protonation ability of two amines? For example, is the protonation ability of n-butylamine more than morpholine?
Hi everybody. I have a question about study kinetics. So, I did electrolysis by dissolving organic compounds with aquades as a sample under acidic conditions with Na2SO4 as electrolyte, with additional H2O2 (Fenton reaction) using iron as anode and graphite as cathode. In discussing the study of kinetics, I found that if the kinetic graph that R2 close to one or almost linear is in pseudo-second order graph, what does this pseudo-second order mean? what does pseudo-second order actually mean? i was told that "the pseudo explains that something is involved but doesn't appear in the rate law, for example the solvent or there is usually the fraction of the reactant that matters" is that true? So, if what is meant by second order is that there are two reagents that have an effect in this case, for example H2O2 and Na2SO4, but in pseudo-second order something is involved but it doesn't appear, what is it? also, if you also know, what kind of reaction mechanism that produces the pseudo?
Thanks in advance
I want to simulate a premixed combustion case with Hydrogen/air (or oxygen) chemistry.
I know simulating a non-premixed combustion case with hydrogen/air detailed chemistry means injecting hydrogen as fuel and air as oxygen at a particular temperature and pressure and using any available chemical mechanism (GRI, UCSD, etc...).
But, what is meant by simulating premixed combustion with detailed chemistry?
:I don`t understand this bold part
The mono- and bidentate bonding are formed via protonation of the surface hydroxyl group and releasing one water molecule, leading to a strong P-O-M bond.
Article title:Organic Hole Transport Layers for Efficient, Stable and Scalable Inverted Perovskite Solar Cells
I saw this sentence .Hydroxyl group and amino group are the both nuclephilic. So no reaction will take place
I have prepared a sample and apparent physical properties show excellent coverage, but I do not how to explain. can anyone help me?
I am carrying out a Research on the effect of blended learning on senior secondary school students achievement and retention in Chemistry. Could someone
help me with materials?
would like to learn more about appropriate material for the application of PPE in Epidemiology.
As all the material seems to be Polyethylene/Polypropylene, would love to learn, whether it is possible to use Polyamide material instead? Are the properties sufficient?
If Polyamide does the job, are normal Snowboarding and Fishing Overalls an alternative to the ordinary Hazmats?
Cherish your feedback.
Defining the dilution factor is very important when we are working at the level of ppb (parts per billion) or ppt (parts per trillion). Other day, I was working on plant biomass samples to analyze available Si (Silicon) in plant biomass. I have gone through several steps of dilution and became so confused about what is DILUTION FACTOR. I did several dilutions at several steps (digestion, adding chemicals, again diluting to come up with the range of AAS) and it became so complicated. As always, I approached Dr. Rafael Santos and he solved this problem very easily, I would say just in 10 minutes when I was struggling for an hour. Finally, Dr. Santos made a good explanation with their whiteboard and step by step he came up with the solution. Again, doing a Ph.D. is not just collecting and analyzing data but also needs to understand the chemistry happening in between. If you don't know how to do it then seek help. Asking someone doesn't mean your basics are not strong, asking someone means you know what you're looking for but you don't know how to approach it. I am thankful to have Dr. Santos as my mentor, peer and guide. PS: Here's complex whiteboard solution in the picture :) #ppb #ppt #help #academia #PhD #chemistry #data #AAS
Research chemists continue in their slow uptake of preprints. I've lately suggested one key reason for this unique behaviour of scholars in the basic sciences in two OA studies, one published by Publications:
and another by Insights:
What is your opinion on the origin of this delay? Has your team recently embraced preprint publishing? What are your favorite preprint repositories?
Thank you in advance for your insight.
Does anyone has an experience with sodium tert-butoxide? How dangerous it actually is?
Do I need to use a glovebox while weighting and handling it?
Do I have to dissolve it in THF at -30C or room temperature will also do?
How do you store it after the can is opened?
We have 100g of sodium tert-butoxide in total, the planned amount for my synthesis is ca. 1.5 g.
This is a graphical abstract image from one of the paper of eminent total synthesis chemist KC Nicolaou. Can anyone tell me how I can draw such type of image?
I am working on different polymers and modifying them chemically and I want to write the chemical reaction. If I want to confirm whether the proposed chemical reaction is right or wrong, is there any software or something?
Thanks for your help!
To set things clearly: I am a PhD student working on the process implications of electryfing the ammonia production by replacing conventional SMR with Water Electrolysis. A part of my preliminary work is to assess the difference in theoretical minimum energy consumption. To do so, I have calculated a first approximation by summing up the reactions (SMR, Water gas shift, Haber-Bosch,...) and calculating the enthalpy of the resulting "total" reaction. I have done this for the "Water Electrolysis + Haber-Bosch scenario" and validated the minimum with values from the literature.
However, for the conventional "SMR + Haber-Bosch scenario", values from the literature are different. To be more specific, here is the energy minimum calculated in the following conference paper:
(...) the theoretical minimum of energy consumption for the process itself (represented by LHV of methane) is 22.2 GJ/t NH3 (...)
Conference Paper 2. Kirova-Yordanova Z, Energy Integration and Cogeneration i...
So here is my question: Why use the LHV of methane (instead the enthalpy of reactions) to calculate the energy minimum ? I feel like this is incorrect as I do not take into account the synthesis of methane.
Thanks in advance for any answers,
Hope you are doing well!
What are the best books in Materials Science and Engineering (Basics and Advanced)? Moreover, what are the best skills (or materials topic related) that materials scientists have to develop and to acquire?
Thanks in advance
This statement is claimed by
Simplistic notion of law of mass action or common ion effect cannot explain it . So what is the reason?
Please do not refer to the references on the paper
Kron I, Marshall SL,
May PM, Hefter G, and Konigsberger E (1995) The ionic product of water
in highly concentrated aqueous electrolyte solutions. Monatshefte für
Chemie 126: 819–837.
what are the possible instruments to use to obtain the purity of a powder (NaCl sold in a pellet form) (has 99% purity or above)?
the cheapest instrument to the expensive one if possible according to your experience
Thank you in advance
Hello everyone. I need a little help here.
can we use essential oils to reduce chlorinous odor in a hypochlorous acid solution without decreasing free chlorine or pH value? any toughts and propositions are much appreciated
0.1 N concentration solution of both was taken, with HCl as titrant abd HPh as indicator. After reaching the endpoint of colourless condition, the colour reappears after continous shaking for 5 mins. even sometimes after 15 mins. How to be sure of that this much time is enough, for shaking to confirm completion of titration?
i have a general question about tissue culture.
I have found the following recipe for Epipremnum Aureum "Marble Queen":
Leaf Explant: MS Medium + 4.54 µM TDZ + 1.07 µM NAA (Thidiazuron in Micropropagation of Aroid Plants by Chen and Wei (2018), p. 105, DOI: 10.1007/978-981-10-8004-3_4)
Specifically, I have the following questions.
1) Do i only need to autoclave the agar with distilled water (I use a pressure cooker for this) and when the agar has cooled down a bit just add the MS, TDZ and NAA and mix it or do i need to autoclave the MS as well?
2) Will the TDZ dissolve in the agar water at all and how hot can the agar water be to add the MS, TDZ and NAA?
3) Is it even necessary to autoclave the water incl. agar (in the pressure cooker) if I clean all the jars with NaClO (sodium hypochlorite)?
Thank you in advance!
Kindly discuss your ideas and viewpoints on the origin of life and the RNA world hypothesis.
What are the contradictory views on why researchers are still unsure about the origin of life through RNA or such analogous molecular intermediate pre-cursors preceding its existence?
"The general notion of an “RNA World” is that, in the early development of life on the Earth, genetic continuity was assured by the replication of RNA and genetically encoded proteins were not involved as catalysts. There is now strong evidence indicating that an RNA World did indeed exist before DNA- and protein-based life. However, arguments regarding whether life on Earth began with RNA are more tenuous. It might be imagined that all of the components of RNA were available in some prebiotic pool and that these components assembled into replicating, evolving polynucleotides without the prior existence of any evolved macromolecules. A thorough consideration of this “RNA-first” view of the origin of life must reconcile concerns regarding the intractable mixtures that are obtained in experiments designed to simulate the chemistry of the primitive Earth. Perhaps these concerns will eventually be resolved, and recent experimental findings provide some reason for optimism. However, the problem of the origin of the RNA World is far from being solved, and it is fruitful to consider the alternative possibility that RNA was preceded by some other replicating, evolving molecule, just as DNA and proteins were preceded by RNA." - Robertson and Joyce
[This is as per the explanation by Michael P Robertson and Gerald F Joyce in the article: "The origins of the RNA world." published in the Cold Spring Harb. Perspect. Biol. 4, a003608 (2012).]
The scientific community must resolve this contradicting conjecture through rational discussion and debate backed by strong experimental evidence on what must be the pre-cursor molecule to the Origin of Life if it is not RNA!
i got my phd awarded recently in chemistry. i want to do post doctoral fellowship in abroad. i request you to suggest me a good country and at the same time a good institute with all details.
We are testing new chemicals for redox flow batteries. We consistently see this weird potential "x" with galvanostatic bulk electrolysis cycling experiments in an H cell, has anyone had this issue before? We have this same issue with the novel anolyte/catholyte chemicals we are testing, so we ran a bulk electrolysis experiment with Fc/Fc+ symmetric cell to see if the issue persisted (both with membrane and with fritted H cells). I see this potential crossover all the time with 100% and 80% SOC experiments, I'm going to test 50% SOC to see if the crossover remains. The reference electrode seems fine based on CV experiments, the reference electrode issues are the only thing I can think of. Isn't it theoretically impossible for the oxidation to start at a more negative potential than the reduction? I see some solvent loss over the period of the experiment. This is the first redox cycle and the crossover is consistent throughout the experiment.
Symmetric h-cell setup
0.001 M Analyte (Fc/FcPF6)
0.1M TBAPF6 in MeCN
10 mL Volume on each side
AMI-7001 selective membrane
BASI nonaqueous coralpor fritted reference electrode (0.01M AgNO3 in 0.1M TBAPF6 in MeCN)
0.27 mA for 1 h (100% SOC)
Forgive some of my ignorance in the math for thermodynamics and heat exchange but my background is heavier in Chemistry and could use some help.
The project is to keep about 70L of water in an aquarium at 17C when the ambient temperature is 22C in the room. The original project built had the following set up:
(Top to Bottom):
1. 80x80x38mm fan running at 5700 RPMs and 76CFM
2. 80x80x20mm copper fin heatsink (0.5mm fin thickness and 40 fins with a 3.5mm bottom thickness)
3. 2-TEC1-12706 hot side towards heatsink, cold side down towards water block (Imax: 6.4A, Umax: 15.4V, Qmax: (dT=0) 63W, dTmax=68C)
4. 40x80x12mm water block centered under the heatsink (surrounded on the sides with 20mm styrofoam and 10mm styrofoam at the back)
5. ~26mm thick styrofoam
6. Wood base
• All power is supplied by an AC/DC converter (12V 20A 240W)
• Power to the system is managed by a W1209 Temperature Control Module (Relay)
• Water flow is achieved by a 4L/min water pump (slowest I can find)
This set up is only cooling the water to 18C at night and will slowly creep up to 18.7 across the day so I know this set up is not keeping up with the heat load. (also worth noting that output temp is about 1.5-2C cooler than input temp to the waterblock). My hypothesis is that the water does not have enough time in the water block for good thermal exchange or that the cooler is not creating enough of a dT in the water block to absorb the amount of heat needed to in that cycle time. The fact that the Aluminum water block has a 5x lower specific heat than water is what is making me think either more contact time or great dT is needed.
My thoughts were to swap out the water block for an 40x200x12mm water block and increase the number of peltier coolers from 2->5 and going with the TEC1-12715 (Imax: 15.6A, Umax: 15.4V, Qmax: (dT=0) 150W, dTmax=68C).
This is where is am lost in the weeds and need help. I am lacking in the intellectual horsepower for this. Will using the 5 in parallel do the trick and not max out the converter? OR Will using 5 in series still produce the needed cooling effect with the lower dT associated with the lower amperage? Or is there another setup someone can recommend? I am open to feedback and direction, thank you in advance.
I have a chemical I dissolve in DMSO. But if I put it in the centrifuge and spin it, all the chemical 'bits' will drop out of its dissolved state and form pellet on side of eppendorf.
Hey, I have been looking for it a lot. Are there sigma + - constants for meta substitution?
And also I couldn't find the sigma * constants.
I am preparing a compilation file for doing MESMER calculations but I am having an issue. I am running some g08 calculations with acetyl and it seems like the transition state from for going to the RO2 to QOOH is unstable as the difference between the target energy and the calculated energy differs by about 0.1 - 1.1. There is too big a difference in the energy barriers between the RO2 and QOOH, but all other energies for the stationary points in the channels are comparative to the expected value. The IRC from the obtained transition state gave a significantly high "jump" in the potential energy graph. Would anyone happen to know what is going on?
We are planning to extract phosphorus from biochar by organic acids. If anyone has some procedure (concentration of organic acids & steps) please inform.
The common method for phosphorus solubilization efficiency measurement of soil microbes is zone formation in agar media (generally Pikovskaya media) but this is a qualitative study. However, there is also a liquid culture method with insoluble phosphorus in liquid media. The estimation of available phosphorus by ICP-OES is quite promising and precise.
I am currently restarting my work on battery management systems, I plan to use Lithium Iron Phosphate cells for their better energy density and relatively better resistance to thermal behaviour than few other commonly sought after battery chemistries. I require some help with good materials or references to help me accomplish BMS for 2W EV. I see that there are Kalman filter based estimations available, but they seem complex and expensive in terms of computations such algorithms require to be implemented.
Kindly request the experienced fraternity to guide me to understand and implement SOX estimation for LiFePO4 Cells.
Thanks in advance.
Dear science community!
I need your help, please!
I`m totally disapointed and at a loss!
In 2020 (at the end of October) there were the IOP Conference Series: Materials Science and Engineering (ICoSiET 2020). Me and my colegues took part in these conference. As the result (like a result of any other conference) the thesis collection should have been published (at the 4th quarter of the 2020)). Unfortanately, these collection still haven`t publised (despite the fact that 2021 is already at its end).
So, I wonder, if there are anybody, who know something about this situation? Maby there are any of those who also waiting for their thesis?
We have wrote lots of messages to the organizators and the head of the university (in which this conference took place) but they stoped to respond us.
I think this situation shows disrespect for the conference participants. And I believe that such situations should be inlighted in our community!
Thank you, for your attention!
We are doing a fab process involving a patterned titania layer sitting on quartz. We now want to etch a few microns of the quartz underneath the titania, in order to "release" the slab. What could be a could wet etching chemistry to etch quartz without etching (too much) titania?
Can you please suggest some *primary amine protecting group* which one do not chemically disturb by *nBuLi* reagent.
I already tried with PMBCl and Boc
In *PMBCl*, it facilitate ortho direction by itself only.
In the case of *Boc* it doesn't stable, hence it cleave during the reaction and enhance the formation of unwanted side reaction.
I'm studying the chemistry of below listed protecting compound
2) Trimethylsilyl chloride
Please give your suggestion which one is compatible protecting group for primary amine in presence of nBuLi reagent.
I am looking for a topic to start my research in chemistry. something which is untouched so far or where research gap persists. A topic which has national and international importance. Completed my coursework so far.
I have synthesized the metal nanoparticles and I want to know that the size of magnets used for stirring purpose has any effect on size of nanoparticles so does the speed of stirring.
I am using commercially available vitamin A mix for a project. It comes in capsules and is very dense so I thought to dilute it with soybean oil.
The vitamin A solution has an approximate density of 0.8523 g/mL (I calculated this by filling 0.3 ml of the VA solution in a microtube and then weight it [minus the tube weight of course] and it was 255.7mg). Then I added 0.3ml of soybean to the microtube and mixed them. This allows me to easily use a micropipette but now I don't know how much vitamin A solution I'm taking each time (in 20ul of the solution for example).
I need this because I add the carotenoids to a feed and I need to know how many mg I'm adding.
This might have a very simple solution but the fact that is the oil is throwing me off. Thank you in advance.
Heterogeneous catalysts (CaO, MgO, ZnO) have been shown to be less effective in low methanol and oil mole ratios. So, what is the best mole ratio for a heterogeneous catalyst in transesterification?
Collected the FTIR spectra of an unknown polymer sample and tried to match with my database.
But it is not matching with any entry of my database. Indeed quite different from the existing entries. So please help me out in identifying its chemistry and how can I do it in future?
i'm looking for reacting gaseous reactant with a liquid reactant, resulting product is gaseous, please tell me how to do such reaction and collect product with accuracy.
If you have a substance of density x g/mol with boiling point y and one with density z and boiling point a and we make a 90% mix of 1 and 2, what is the resulting density and boiling point?
As well known
In almost all papers the experimental section is so short and not detailed for instance no clear weights setup and so on
Where can we find expanded detailed narration of experiments and methods
I have tried to cure the CNSL resin with a Hot air oven of 180 degrees Celsius. Still, I am not getting the proper solidification of the resin, the specimen which is kept in a Hot air oven is in a spongy state. I want to know the process/ steps/ procedure for curing the CNSL resin?
Hi! I have two small molecule structures, and I need to create a model of them connected by a bond. I have found plenty of software where I can upload one, and then add or subtract atoms one at a time (PubChem Sketcher, Avogadro, there are tons available as web tools or downloadable software) but I have yet to find one where I can upload two molecules and then... combine them. This seems like such a simple task but I've run out of ideas! I would love any suggestions. If you cannot think of any free tools, suggestions for paid software is also welcome.
In biodiesel production through transesterification, various of heterogeneous catalysts could be utilized. However, each heterogeneous catalysts are showed different yield. My question is What are the factors of heterogeneous catalyst that affect their activation during transesterification?
What is the chemistry behind chloropicrin used as a pesticide, as it available in three different formulation registered in Pakistan e.g. in one registered product it act as an active ingredient, in 2nd it as an inert ingredient while in third one it act as a warning agent.
Over the last few months, I have come across several posts on social media where scientists/researchers even Universities are flaunting their ranking as per AD Scientific Index https://www.adscientificindex.com/.
When I clicked on the website, I was surprised to discover that they are charging a fee (~24-30 USD) to add the information of an individual researcher.
So I started wondering if it's another scam of ‘predatory’ rankings.
What's your opinion in this regard?
I need to find a proper method to prepare sample solution by digestion for Pt-Pd-Rh elements from spent automotive catalysts. Any suggestion except application of microwave-assisted digestion would help me.
I have purified crude glycerol which is come from as a byproduct of transesterification. I need to know, the purity of the sample after purification. What methods can I apply to get the glycerol purity?
I'm working on metal-organic coordination complexes, I got a wavy and large NMR shifts for some of complexes which I anticipated as paramagnetic.
Can you explain the relation between paramagnetic nature and large shifting in NMR ?
I am engaged in purifiying crude glycerol made from biodiesel. As a first step, acidification was carried out with phosphoric acid, however, K3PO4 percipitate must contain inorganic salts. But, in my case, I did not see any salt after the pH of the medium dropped to 1. What is the reason?
Glycerol is the primary by product of the transesterification reaction which is in the biodiesel production. However, this crude glycerol have contaminated with various of compounds ( monoglyceride, diglyceride, triglyceride, salts, FFA..etc). My question is, what are the possible value added produt that can be produced ny crude glycerol whithout a purification?