Organic Chemistry - Science topic

Ricarda Koopmann I'm quite satisfied with the purity and the quantity of my product in the organic phase. I believe it's fairly pure based on the IR spectra. Thank you very much for your response and advice

Use Lamar Standardized Method or the Larry G. Butler Method for quantifying fulvic acids

Refer all these articles Pejman Rahmani Nejad

1.

2.

3. 10.3390/polym15020267

According to IUPAC, the procedure is as follows:

1. Find the largest possible cycle (in red) = the main cycle that has more atoms on one side (black spheres, first number in square brackets) and fewer atoms on the other side (red spheres, second number in square brackets).

2. Find the main bridge (i.e. the link on the main cycle that divides it into the smaller and larger number of atoms) so that it has as many atoms as possible outside the main cycle (blue spheres). In the second case it is clear, in the first case both bridges have one atom, but the black one has priority in numbering. This main bridge will be the third number in the square bracket.

3. Find the side bridge (the only one left). This will be the fourth number in the square bracket (turquoise spheres) with the exponent of the two atoms that make up the secondary bridge.

In the second case, the bracket will be as follows: [6.2.2.0exp2.7].

I don't know if that is clear enough. Hope it helps...

Dear Trieu Phu Hau , wouldn't both products come from the intra-cyclization or a partially epoxidized pyrogallol unit? depending on the position of the OH and of the O-CH2-Epox groups (both ortho to each other) one would get one of the 2 structures you propose. Thanks for your time and consideration.

What about alumina and using a polar solvent like acetonitrile? I've purified metal complexes of silica with an automated flash chromatography system, and also purified metal complexes on alumina with acetonitrile as the solvent.

It's because in sucrose the anomeric C atoms of glucose and fructose are both involved in the glycosidic bond. That's why they can't change their configuration without breaking the glycosidic bond. In reducing disaccharides like maltose the anomeric C of the "second" glucose is "free" (hemiacetal only). Therefore, the open-chain form and all possible configurations (alpha, beta, furanose, pyranose) of the second sugar are available without breaking the glycosidic bond.

As you will be aware, plants are a very rich source of phytochemicals and this will be reflected in your aqueous extract. The IR spectra of your extract will be complex, containing the overlapping spectra of every compound. You will not be able to identify any individual compound with any degree of certainty.

If you want to identify the components of your extract then you need to resort to a Metabolomics type experiment. You need to add in several chromatographic steps and then resort to GC-MS (headspace for volatiles), after appropriate derivatisation, and to LC-MS. The spectra can be searched against various libraries. Even then you will be left with many unknowns.

Another crucial information may be supplied by the company concerning the type/name of the initiator used in the addition ROP of ethylene oxide. This is important in that end groups usually have their own intrusion in many properties and behaviors. Also you may ask if the PEG 100 has been the subject of further post- polymerization treatment. Best of luck in your work.

You might be able to precipitate the DCU from cold ethyl acetate, cold diethyl ether or toluene.

You could also replace DCC by EDC as the corresponding urea is soluble in acidic aqueous.

My question is related to a recently completed project: "Integrating Superregenerative Principles in a Compact, Power-Efficient NMR/NQR Spectrometer: A Novel Approach with Pulsed Excitation"

https://arxiv.org/abs/2312.08491.

I am looking for an application to commercialize the detector idea, taking advantage of its attributes such as low power consumption and simplicity of design.

Total nitrogen can be determined through the oxidative digestion of all digestible nitrogen forms to nitrate, followed by quantitation of the nitrate. Kjeldahl method is the very old and conventional method but The enhanced Dumas method is an automated instrumental technique that is beginning to compete with the Kjeldahl method as the standard method of Nitrogen analysis due to its rapidness and ease of use. In Dumas process high cost initially but fast ,it requires 3/5 minutes for each sample analysis.

It is better NOT to use it. Organic compounds can degrade over time, leading to changes in their chemical properties and potential loss of effectiveness. Here are some pros and cons of using expired organic compounds:

Pros of using expired compounds:

1. Cost-saving: Expired compounds may be available at a lower cost or even free of charge, making them attractive for researchers or industries operating on a tight budget.

2. Limited applications: In some cases, expired compounds may still be suitable for certain applications where their degraded properties do not significantly impact the desired outcome. For example, if the compound is being used as a reference standard or for non-critical preliminary experiments.

3. Educational purposes: Expired compounds can be useful in educational settings for teaching purposes, demonstrations, or as practice materials for students to familiarize themselves with laboratory techniques.

Cons of using expired compounds:

1. Decreased potency or activity: Over time, organic compounds can undergo chemical reactions that lead to degradation, resulting in reduced potency or activity. This can affect their performance in experiments or applications, making them less reliable or ineffective.

2. Inaccurate or inconsistent results: Using expired compounds can introduce variability and uncertainty in experimental results. This can be problematic, especially in research or industrial settings where accuracy and reproducibility are crucial.

3. Safety concerns: Expired organic compounds may pose safety risks. Their degradation products or impurities could be toxic, unstable, or reactive, potentially leading to hazardous situations during handling or when used in reactions or processes.

4. Unreliable data: When using expired compounds in research or industrial processes, the obtained data may not be reliable or representative of the compound's true behavior. This can hinder scientific progress, lead to erroneous conclusions, or impact product quality in industrial applications.

5. Regulatory compliance: In regulated industries, the use of expired compounds may not comply with quality control standards or regulatory requirements. Using expired compounds could result in non-compliance, potentially leading to legal or regulatory consequences.

Hope it helps:credit AI

Hello.

I've another question. I would like to do a DCC coupling of PMAA (100 kDa) with an amine. I already found a paper where they dissolve PAA in NMP under stirring at 60 °C for 24h. In my case PMAA didn't dissolve very well in NMP - the solution is very turbid and there is a small precipitate at the bottom of the flask. I can't use water because DCC doesn't dissolve in it. Are they any recommendations from your side. I also tried the synthesis with EDC HCl in a mixture of THF/H2O but it didn't work well so that I would like to switch to DCC instead. Thanks in advance.

Without more details of the structure, it is hard to say. But things to consider: your 3 substituted piperidine actually has 2 stereogenic centers. N1 and C3. N1 can readily invert and may be in equilibrium between 2 forms. Removal of the Boc may alter the equilibrium.

there can be other acid catalyzed isomerizations but without the detailed structure it is hard to know if they are relevant.

You can try to focus on crystallization. Schiff base crystallization is generally achieved using acetonitrile, acetic acid, ethanol water, DMF water, and acetone

To Mr. Varshney: The invitation to write a chapter is inappropriate content for the Q&A section of Researchgate.

John Canham you are correct, although I would rephrase the mistake as the user not allowing the TLC chamber to saturate with vapor before running the TLC plate.

See: Let Us Teach Proper Thin Layer Chromatography Technique! | Journal of Chemical Education (acs.org)

you are welcome

Have you tried celite filtration?

You should optimize the complex with both reactants in a favorable position / orientation for the possible proton transfer to occur, with an appropriate level of theory and basis set. The final position of the hydrogen could provide an answer to your problem: if it stays on the acid it is H-bonding, and if it is transferred to the basis it is an acid-base reaction.

your results can be more accurate if you take the solvent into account (at least as a polarizable continuum) and if you compensate for basis set superposition error (either using a fairly large basis set or using the counterpoise scheme).

Carbonyl and amino group can easily generate Schiff base (imine), the reaction is a dehydration reaction, the carboxyl and hydroxyl groups in the reactants have no effect on the reaction, please note:

You also need to consider whether the compounds are likely to chemically or biologically degrade between spiking and extraction

p-Anisidine turns black due to areal oxidation and even recrystallization using active charcoal too some times no better quality of desirable purity of p-anisidine is obtained. For purification it is best to distill p-anisidine under reduced pressure (avoiding use of water circulation in the condenser) . I have purified p-anisidine many times by distillation under reduced pressure to obtain -anisidine as perfectly white / colorless solid.

DNP (or DNPH) normally is a easily available commercial material. If required it can be purified by recrystallization with MeOH or EtOH using little co-solvents like dicholomethane or benzene (hazardous, to be used with care). But normally it is not necessary to purify DNP itself. For preparation of 2,4-dinitrophenyl hydrazone derivatives, DNP solution (Brady's reagent) is used. To prepare Brady's reagent dissolve commercial DNP (4 gm) in MeOH (85-100 ml) (taken in a dry 250-500 ml beaker) by slow and gradual addition of about 15-20 ml of conc. H2SO4 with stirring (external cooling may be necessary) till DNP dissolves completely and goes into solution (please stop addition of sulphuric acid as soon as DNP dissolves completely). On cooling to room temperature some crystal of DNP salt (light yellow needles) may appear.....filter it or dissolve it with little more MeOH to obtain clear Braddy's reagent. This is sufficienly pure for use.

Setting up a high throughput system for ultrasound irradiation/sonication, especially for your specific application of screening photosensitizers in cell cultures, requires careful consideration of various factors. Given your current understanding and equipment, here are some steps and considerations to help you set up an accurate and precise high throughput system:

Coupling Agent and Sterility:

• A coupling agent is often used to facilitate the transmission of ultrasound waves from the probe to the sample. It helps minimize air gaps that can impede wave propagation. Sterile coupling gels or fluids can be used to maintain aseptic conditions for continued incubation.
• Plate Positioning:
• Based on the literature you mentioned, positioning the probe underneath the plate in a 2x2 square cluster seems to be a common approach. This can help focus the ultrasound energy on specific wells. The use of a coupling agent between the probe and the plate is crucial for effective transmission.
• Plate Material and Ultrasound Transmission:
• The choice of plate material can affect the transmission of ultrasound waves. Opt for plates that are compatible with ultrasound transmission, such as plastic or materials with low acoustic impedance. Glass plates might attenuate the ultrasound energy.
• Even Ultrasound Stimulation:
• Achieving even ultrasound stimulation across the entire plate can be challenging. The setup you mentioned with a probe underneath each cluster can help localize the energy, but it might not provide uniformity across the entire plate. Experimentation and optimization are key to finding the best setup for your specific needs.
• Impact on Adjacent Wells:
• Ultrasound waves can interact with neighboring wells. While some energy might pass through to adjacent clusters, the effect would likely be attenuated. However, it's important to monitor this potential interaction, especially if you're aiming for precise and controlled results.
• Probe Configuration:
• Since you're using a probe (as opposed to a water bath), consider whether modifying the probe configuration, such as using an array of smaller probes or optimizing the positioning, could help achieve more even energy distribution.
• Calibration and Dosimetry:
• Accurate dosimetry is essential for consistent results. Calibrate your ultrasound system to ensure that the intended energy levels are being delivered to the samples. This calibration can involve measuring the intensity, power, and frequency of the ultrasound waves at different points within the plate.
• Temperature Monitoring and Control:
• Ultrasound irradiation can lead to localized heating. Monitor and control the temperature during experiments to ensure that any effects observed are due to sonication and not temperature-induced changes.
• Safety Considerations:
• Ultrasound can induce cavitation, which may affect cells and compounds differently. Carefully consider safety protocols and ensure that the chosen parameters do not cause harm to the cells or compromise the integrity of your experimental setup.
• Collaboration and Consultation:
• Collaborate with experts in the field of ultrasound and sonication. Consult with colleagues, mentors, or specialists who have experience in similar setups to gain insights and advice.

Remember that achieving an accurate and precise high throughput system requires iterative experimentation and optimization. As you become more familiar with ultrasound physics and its interaction with your samples, you'll be better equipped to fine-tune your setup for optimal results.

Tween 80 is an ester formed from the reaction of polyethoxylated sorbitan and oleic acid. Though the reaction product is neutral, a small amount of sulfuric acid is sometimes used to catalyze esterification reactions such as the one that forms Tween 80. Is it possible that Tween 80 contains a small amount of residual sulfuric acid from the reaction that produces it? This would account for the decreasing pH as you increase the concentration of Tween 80.

For the formation of diamine the first method may be some what better and can lead to product but during alkylation with RBr base like NaH or BuLi may be necessary.

The second method may fail. Alpha, beta amides are not good Michal acceptor hence attempt of Michael addition of amine to alpha, beta unsaturated amide may fail or can give very poor yield. Another problem is very natural tendency of polymerization of acryloyl chloride and acrylic acids....it can lead poor yield with impurities.

As an alternate method peptide coupling reagents like DCC (or DCCD) (dicyclohexyl carbodiimide), CDI (Carbo diimidazlole) can be used.

One equivalent of diamine, 2 equivalents of mono carboxylic acid can be coupled in presence of 2 equivalent. of DCC or one equivalent. of CDI on anhydrous THF or DCM solvent at r.t or lower temperature can furnish the desired diamide. It can then be reduced to diamine derivatives with suitable reducing agents like LAH etc.

If One uses a dicarboxylic acid as source of amide carbonyl then one equivalent of dicarboxylic acid 2 equivalents of amine should be allowed to react with 2 equivalent of DCC or 1 equivalent of CDI. Plenty of procedures are available in organic synthesis (collective volumes), proper journals or references may be available in Organic Chemistry portal. Please see Mitsonobu reactions , Peptide Coupling reagents etc. , Application of reagents like DCC, CDI, DEAD etc. If One uses ROH instead of RNH2 esters can also be prepared.

The method is very good and high yielding too.

Show quoted text

DEL which entails a collection of small molecules covalently linked to DNA that has unique information about the identity and the structure of each library member.

In future, promising job opportunities will be beconing on those professionals who are clinically savvy especially in the pharmaceutical/drug and biomedical sciences. More human capital will be needed in numerous drug discovery programmes in future.

Henry Kolge I diluted DMSO to 9:1 (DMSO:water).

There are some purification methods covered in Armarego p 400 , but none appear easy, good luck. Google "continuing demand for the Purification of Laboratory Chemicals book" and there may be a copy online.

Thank you dear Prof. Chuck A Arize for your valuable link. Best regards.

Yes, there are several purine-based ionic liquids that have been described in the scientific literature.

Examples of purine-based ionic liquids include 1-butyl-3-methylimidazolium adenosine monophosphate ([BMIM][AMP]), which was first synthesized and characterized in 2011 (reference: "Synthesis and characterization of a new purine-based ionic liquid: 1-butyl-3-methylimidazolium adenosine monophosphate" by L. Zhao et al., in Tetrahedron Letters, vol. 52, p. 1130-1133, 2011).

Other examples of purine-based ionic liquids include 1-butyl-3-methylimidazolium guanosine ([BMIM][GMP]) (reference: "Synthesis and characterization of a novel purine-based ionic liquid: 1-butyl-3 -methylimidazolium guanosine" by L. Zhao et al., in Journal of Molecular Liquids, vol. 170, p. 63-66, 2012) and 1-allyl-3-methylimidazolium hypoxanthine ([AMIM][Hpx]) (reference : "Synthesis and Characterization of a New Purine-Based Ionic Liquid: 1-Allyl-3-methylimidazolium Hypoxanthine" by L. Zhao et al., in Chemical Research in Chinese Universities, vol. 32, p. 157-161, 2016) .

Dear Noor,

Actually, PHB in nanoparticle nor crystalline nor amorphous.

Burst release at different pH is caused by nature of active ingredient and drug load coefficient.

Also it depend on buffer you used for pH stabilization.

Moreover, if you have drug overload due to salt formation between carboxylic group of PHB and amine group of drug loaded, in pH range less than 4,5 these salts undergoes ion exchange and drug release.

Alan Lee TLC looks very clean, I'm jealous lol!

Your plan sounds awesome and I hope it checks out.

Have a nice day!

Emergence has become the front and center of my research in the couple of last years. To be capable to understand its working in depth, I had developed several open-source Python programs (ranging from the simplest one to the most advanced one) that enables everyone first to understand the cellular automata programming, and later apply them to studies of emergence that is occurring in so-called 'Game of Life'.

Quite a few videos depicting animated emergent structures are accessible in my profile at sections about data and software: e.g., logic-gates AND, OR, NOT, and quite a few emergent structures emerging in generalized neighborhoods of the original GoL. The latest paper is describing another interesting area, the design of error-resilient emergents, which can withstand the of 1% of errors into their evaluation process.

With respect to the questions provided in this answer. I highly recommend watching said videos and even run the open-source GoL-N24 Python software and try to play with emergence on your own. The personal experience with those simulations is always the best way to start to understand that we do not understand the theory of emergence!

Everyone is welcomed to play with emergence. One thing is sure, there are hiding huge treasures both experimental and theoretical in such 'playing' with the concept of emergence. Hopefully, this year will be published a paper that is going to address, at least, some root questions about emergence and its very principles (stay tuned).

References:

https://www.researchgate.net/publication/355043921_The_simplest_Python_program_simulating_a_cellular_automaton_model_of_a_complex_system_the_'Game_of_Life'

https://www.researchgate.net/publication/356759719_Computer_Components_Simulated_Using_the_'Game_of_Life'_cellular_automaton_logic_gate_AND

There are all three logic-gates avaiable

https://www.researchgate.net/publication/357285926_Python_program_simulating_cellular_automaton_r-GoL_that_represents_robust_generalization_of_'Game_of_Life'_sample_runs

https://www.researchgate.net/publication/361818826_Robust_massive_parallel_information_processing_environments_in_biology_and_medicine_case_study

Alcohol and formaldehyde preservation solutions are commonly used in the preservation of skeletal carbonates. However, there is a concern that these solutions may leach elements from the skeletal carbonates, which could potentially affect the accuracy of isotopic and elemental analyses.Several studies have investigated the effects of alcohol and formaldehyde preservation solutions on skeletal carbonates. One study found that formaldehyde preservation did not significantly affect the stable isotopic composition of skeletal carbonates, but it did result in a slight decrease in calcium concentration. Another study found that alcohol preservation did not significantly affect the stable isotopic composition or elemental concentrations of skeletal carbonates. However, some studies have reported that both alcohol and formaldehyde preservation solutions can leach elements from skeletal carbonates. For example, one study found that alcohol preservation caused a significant loss of magnesium from coral skeletons. Another study found that formaldehyde preservation caused a significant loss of strontium from bivalve shells. Overall, the effects of alcohol and formaldehyde preservation solutions on skeletal carbonates appear to be dependent on several factors, including the type of carbonate, the concentration and duration of exposure to the preservation solution, and the specific element being analyzed.

Greetings Ali Safaa

To solve for molarity (M) in the equation:

ppm = M x m.wt x 1000

We can rearrange the equation as follows:

M = ppm / (m.wt x 1000)

So if you have a solution with a concentration of 50 ug/ml and you want to know the molarity, you would first need to know the molecular weight of the solute. Let's say the molecular weight is 100 g/mol.

50 ug/ml x 1000 = 50,000 ppm

M = 50,000 ppm / (100 g/mol x 1000)

M = 0.5 M

Therefore, the molarity of the solution is 0.5 M.

It is important to note that ug/ml and ppm are not equivalent units of measurement. Ug/ml is a unit of concentration based on mass per volume, while ppm is a unit of concentration based on the number of parts per million. To convert from ug/ml to ppm, you would need to know the density of the solution and the molecular weight of the solute.

For filtering chitosan solutions, it is recommended to use a filter with a pore size of 0.2 µm or smaller

One suitable filter for this purpose is a syringe filter with a 0.2 µm pore size, made of materials such as nylon, PVDF, or PTFE. These filters can effectively remove particles and aggregates from chitosan solutions without causing clogging or loss of chitosan

More than the sign (positive or negative), the indicator of stability versus aggregation will be influenced by the absolute value of the load. In the literature, nanoparticles with a net charge above 30 mV (positive or negative) are said to exhibit good electrostatic stability due to repulsion from each other. However, non-ionic surfactants that can incorporate nanoparticles allow stabilisation of nanoparticulate systems by steric stabilisation as well.

When you say, Zeta potential has become positive, does that mean it was negative before? If so, this is an indicator of instability. Try adding a pH buffer and monitor the size of the nanoparticles to make sure they are not aggregating.

Thank you Qasim Qayyum Kashif, that's very interesting. I appreciate the time you're spending to help with this.

Dear Sumit Bhowmick ,

I would say the reaction forms 1,2-dinitroxyethane, similar to the nitration of glycerin provides 1,2,3-trinitroxypropane (a.k.a. nitroglycerin). 98% Sulfuric acid leads to the protonation of nitric acid, facilitating the nucleophilic attack from an OH group of ethanediol. Do it twice and you get the final product. And as you said, dehydration reactions due to OH protonation can also occur.

But please, stop drinking things (known or unknown) you synthesize in the lab. There are faster ways of dying.

But as i know so far chitosan is insoluble in water, for your consideration.

May explode on heating

Your cyclic peptide also includes a thiazole.

Check

No, citric acid trihydrate crystals will not dissolve in room-temperature concentrated (65%) nitric acid.

You can do either of two things:

1. First, convert a Dowex cation exchanging resin, H+ form, to the desired ionic form by washing with 0.5-1M solution of a salt containing the desired cation followed by the extensive washing of the resin with water. Next, pass, at a slow flow rate, an aqueous solution of your nucleotide through a column containing min. 10-fold excess of the resin prepared as above and wash the column with several volumes of water to complete the elution of the nucleotide. Freeze-drying will give you your nucleotide in the desired ionic form.

2. If your nucleotide is retained on a C18 reverse phase column, you can dissolve the nucleotide in a solution containing the desired cation and apply the solution to the column. Next, wash the column with 3 volumes 0.1 M aqueous solution of the salt containing the desired cation. Next, wash the column with water, min 1 column volume. Finally, elute the nucleotide with 10-15% aq acetonitrile and evaporate the eluate to dryness. It would be advantageous to monitor the UV absorbance of all eluates by an on-line detector and collect only the UV-absorbing fractions. Not all nucleotides are retained by C18 reverse phase, particularly in the step of washing with water. If you decide to use this method make sure to check all eluted fractions.

If you need article access send me doi or link. I will provide you.

Thanks

Hi, the starting material doesn't matter. I would use the unprotected amino acid (its way more cheaper), add dry methanol and at least 5 eq of TMSCl. Starting with an ice bath and after 30 min stirring raise to 40 °C for 2-3 h. Check the reaction progess via TLC. Good luck.

Reactions, which are run for 14 hours, frequently are just sitting on the bench from 6pm to 8am. I would be surprised if it is completed in much shorter time.

Dear Tran Khanh, furan-maleimide is much attractive couple. Please have a look at the following recent review. My Regards

By using 1/2 % of acetic acid you can easily dissolve chitosan

After the first step of an electrophilic addition reaction an intermediate (carbonium ion) is formed (with a much higher energy). There are no more pi-electons.

I would like to recommend you chiller option (green, energy saver and more efficient) instead of the submersible water pump.

NOT MISCIBLE

Using GROMACS to perform molecular dynamics simulation is a very good choice. GROMACS is quite fast, flexible and meantime freely available.

In aqueous media? I'd try solid phase extraction onto reverse phase. Wash with water, then wash with steps of increasing concentration of acetonitrile in water.

I would say yes, but you have to remember not to extrapolate it to another solvent. pKas varies from solvent to solvent. So, one amine can be more basic in one specific solvent, and less basic in another one.

Google Scholar and Research Gate are good websites to get free and accessible articles.

I have replied this question many times in different platforms. But now I have at least three different videos on it. How to protect halogen like bromo and Iodo or chloro while I am doing nitro to amine. Here I am putting a link of youtube. You can look for Nitro reduction with Zn, Nitro reduction with Iron-Beckhamp reduction and Finally you can see the video on Tertiary carbon nitro reduction to amine while sensitive functional groups are present.

Dear Muralishwara Kakunje, TOC (total organic carbon) in water is the classical way. Just use one of these techniques such as the spectroscopic ones. My Regards

@Philippe Roger Bovy, what do you mean by ddeOH recovering. After finishing the reaction, I used dialysis purification using methanol first exchange with waterthen water

Aniketh, This is not true. Chlorine is strongly accepted to the benzene ring.

I have the same problem as you

Thanks for the information

Dear Orkhan Ismayilov, only PS shows poor solubility in diethyl ether, PTFE and PP arr unsoluble in it. For more details on polymers solubility, please have a look at the attached files. My Regards

You can try column chromatography using 100-200 silica with long bed and loading of 1.0g.

I had working in one project and its based on indol synthesis at that time i had successfully separated this regioisomer of indol by this way...it will took some time but it's possible.

Hello Alexander,

many thanks for sharing this very interesting chemical question. I did a SciFinder search on this particular compound and found out that in the previous literature only three different reactions have been reported in which the compound is a reactant and not the product. One is the hydrolysis of the MeO group in 5-position, one is a ring-sulfonation of the outer phenyl ring using chlorosulfonic acid, and the third one is the replacement of the C=O group by a thiocarbonyl (C=S) group. What has not yet been reported are e.g. halogenation reactions.

Good luck with your work!

Dear John Rey Noga this is certainly a good question of broad general interest. As already mentioned by Sengottuvelan Balasubramanian the use of Greek letters varies between different sub-disciplines of chemistry. For example, the letters delta and lambda are often used in coordination chemistry to denote different enantiomers of optically active metal complexes. Other letters are used in organic chemistry nomenclature to denote the positions of substituents on a carbon chain. For some potentially helpful information please have a look at the following links:

https://blog.cambridgecoaching.com/chemistry-tutoring-explaining-greek-symbols-in-organic-chemistry

and

Good luck with your work!

Are you looking for a software that predicts the binding mode/site between metals and protein? If that’s what you mean, molecular docking is what you are looking for. Here is an article that can help to get started. Hope this helps.

Dear Maxim Tiburziano ,

If I remember well, trans to cis (and vice-versa) isomerization of azobenzene results from a π to π* excitation. To properly locate the involved excited-state, I could suggest you to calculate the NTO (Natural Transition Orbitals) to find the one with a major contribution resulting from a π molecular orbital to a π* molecular orbital excitation. This calculation can easily be done via Multiwfn (free) with your *.log or *.out file and certainly *.fchk file from a Gaussian calculation. If you use ORCA with TDDFT, you could generate these NTO via the instruction "NTO TRUE" in %TDDFT keyword if I remember well. Otherwise, a canonical molecular orbital analysis (CMO) from NBO (Natural Bond Orbital) would help you in identifying the excited-state involving most of the π and π* molecular orbitals decomposing them in a rather localized way. But NBO is not free! (you could have a look on Janpa project...)

Hope this could help you!

Hello Rajiv,

thanks for asking this interesting technical question on RG. For a good introduction to this topic please have a look at the following relevant article which might help you in your analsis:

Several drugs described here can be synthesized in 2-5 steps. Unfortunately this paper has not yet been posted as public full text on RG. Thus please check if you can accesss the full text through your institution. Moreover, three of the authors have RG profiles. Thus you can easily contact one of them directly via RG and request the full text of the paper.

I hope this helps. Good luck with your work!

Kindly see also the following useful link: https://www.wired.com/story/how-to-make-hand-sanitizer/

Also check https://www.organic-chemistry.org/chemicals/oxidations/n-methylmorpholine-n-oxide-nmo.shtm

https://pubs.acs.org/doi/10.1021/acs.chemrev.6b00512

The difference between malonyl and 2,2-dimethylmalonyl dichlorides is that the former possesses hydrogens in the alfa position to the carbonyl group. What often happens with acyl chlorides of this sort in the presence of bases is the formation of ketenes by abstraction of HCl by the base. The stronger the base, the greater the extent. ketenes are capable of acylation, but prone to the formation of other products. Phenylenediamine, even with Boc-protection is not an easy compound either. You judgement was quite correct when you were adding the dichloride dropwise at -20oC. Pyridine as a base is a good choice, too. It is likely that you generated a good yield of the desired malonyl diamide, but some colored impurities are hardly avoidable when you have an acyl chloride as reactive as the one you use. If these impurities are critical or the yield is too low, you may wish to react malonyl dichloride with N-hydroxysuccinimide. Once bis(N-oxysuccinimidyl) malonate, a much milder acylation agent, is formed in situ, it can be reacted with mono-Boc phenylenediamine. Good luck with your chemistry!

Here of this reaction, the methyline group's hydrogen is shown as acidic nature. But it is not as usual acidic in nature. If such condensation reaction is truly going to be happening, then must include please the basic medium.