Search results

  1. chem_tr

    Decrasing solubility of quaternary ammonium compound in water

    Hello, I have synthesized a compound with two quaternary ammonium groups and two cyanide groups. I did the reaction in dmf, and after the reaction I poured the reaction medium onto ice-cold water. A little precipitate formed, but I think this is not the compound I want, my compound is still...
  2. chem_tr

    Has anyone heard of P and M notation?

    Has anyone heard of P and M notation??? Hello, A friend of mine has asked a question about a molecule, we think the molecule was a biphenyl molecule with two nitro groups on each benzo unit, along with two carboxylic acid moieties on each ring. So the molecule was shown to be in two isomers...
  3. chem_tr

    Interfacing a PC to a UV spectrophotometer

    Hello, We have an old spectrophotometer which contains an outlet saying "printer/computer", and until now a dot-matrix printer has been attached to it. However, the printer is no longer functional, and I am thinking of interfacing an old PC to the spectrometer. The printer was attached via...
  4. chem_tr

    Help on 19F-NMR

    Hello, A friend of mine has synthesized a compound with pentafluorophenyl groups, and is willing to characterize it via an additional 19F-NMR. However, the person responsible for recording NMR spectra is inexperienced in 19F-NMR, so we need help on recording the spectra. We have...
  5. chem_tr

    About Williamson ether synthesis

    I am planning to perform some Williamson synthesis. However, I have not been successful on obtaining a literature with described procedure. Will I need any procedures? I have looked at Organic Syntheses website (website url), but no procedures on the Williamson's technique. My plan is simple...
  6. chem_tr

    Thin Lead Chromatography help

    Hello everyone, I was poor on TLC before, and am poor now :smile: I want to ask a question to you guys. Please look at the attached zip file with a tif image. My question is very simple: Is it possible to fully isolate the impurities (yellow spot and light olive-mustard-colored...
  7. chem_tr

    A hard electrochemistry question (in my opinion)

    Hello all, As I am preparing for my PhD proficiency exam, I tried to solve some Analytical chemistry problems. and stuck in one. Well, I have attempted to solve this, but have not found enough evidence to study on and solve the problem. What I've done is basicly the following: I am in...
  8. chem_tr

    A question about calorimetry

    I haven't found my textbooks on physical chemistry, so I want to ask the forum members. When we heat 4 liters of water from 10°C to 90°C, and add this to 16 liters of water at 10°C, what will the final temperature be? My brainstorming revealed the following, but I'm not sure if they are...
  9. chem_tr

    A question about gravimetric analysis

    Hello, I have been studying undergraduate level chemistry courses for PhD proficiency exam, and I have very recently been started Analytical Chemistry. I have a simple problem and I solved it in a different way, could you please show me how I can solve it by using the known "gravimetric...
  10. chem_tr

    Synthesis of a nitrile from an amide

    Hello everyone, I watched a MS thesis defence examination on chemistry, and one question was asked to the student, "what is the use of thionyl chloride in the reaction which an amide was transformed to a nitrile?" Unfortunately, there is a "fixed" answer, "to remove water from the reaction...
  11. chem_tr

    4,5-Dibromoisatin synthesis

    Hello, I wonder if this chemical can be synthesized. I have devised a retrosynthetic analysis route, but not sure if this may work or not. I have considered that 1,2-dibromobenzene may be nitrated (or 1,2-dibromo-4-nitrobenzene may be purchased instead) to give nitro derivative, which will be...
  12. chem_tr

    Redox for molybdenum

    Hello, Anyone know something about Molybdenum(V) ions? 1n our university, we instruct an experiment to students, in which ammonium molybdate (\displaystyle (NH_4)_2MoO_4) is reacted with tin chloride with hydrochloric acid. A redox reaction occurs, to my knowledge it should be like that...
  13. chem_tr

    Question about humidity in milk

    Hello everybody, A friend of mine asked me a question regarding one of his milk-processing techniques. He wants to learn if a mathematical formula or a logical approach can be devised. Okay, the question involves a 1 liter-volume-bowl, whose outer (bigger) radius is 160 mm. He didn't say...
  14. chem_tr

    Data transmission

    Greetings, I was asked a weird question, K12 level, but interesting... How is the data transferred through two computers, and how (and what) is it converted to the data again? Please send me some resources about it, or suggest your own ideas. I didn't like mine, so decided to ask in the...
  15. chem_tr

    What do you make of this mechanism?

    Hello, I think the one I drew and included in the attachment is valid for Michael-type addition reactions. Do you make a favor to check the mechanism? I think, the steric hindrance of the more-stable carbocation in vinyl group can not participate in this type of mechanism, it is further...
  16. chem_tr

    Advice about preparing xanthates

    Hello, I'm planning to synthesize a xanthate derivative from an alcohol and carbon disulfide. I will probably need to use sodium hydride to facilitate addition to the double bond, and I need advice about using NaH, and if possible, some experimental details about the reaction. I will look for...
  17. chem_tr

    A question for Graduate students and higher

    Hello. I've enrolled Chemistry Graduation program last year, and I will finish my courses, ready to be "challenged" by PhD proficiency examination. In our country, some instutitions like mine prefer to do this examination by asking EVERY branch, regardless of what subject (or main branch) I'm...
  18. chem_tr

    Help about benzoin condensation

    Hello friends, I am planning to do one new instance of benzoin condensation, with pyridine-4-carboxaldehyde as the carbonyl compound to receive, 2-hydroxy-1,2-dipyridin-4-ylethanone, the resultant benzoin compound. However I have some doubts as suggested in this website, since pyridine...
  19. chem_tr

    Mercury spillage

    Hello, I need advice about how to treat spilled mercury. A friend of mine is going to do an experiment about barometers, and she needs some mercury. I am worried about any accident. As you know, mercury vapors are very toxic for nervous system. Any advice is welcomed. I will immediately do a...
  20. chem_tr

    Pentacoordination of Zinc?

    Hello, I've heard rumors (frankly, not rumors, evidenced by some scientific papers), that zinc(II) ion has coordinated five ligands, four at a plane, and the fifth from top, to form a tetragonal monopyramidal environment. I have some doubts about this, because zinc (II) ion has d10...
  21. chem_tr

    Molecule soluble in chloroform

    Hello, I have a molecule soluble in chloroform. I've tried to learn its pureness with thin lead chromatography on silica gel. After several tries, I've discovered that my molecule is best eluted with 9:1 CHCl3:MeOH (for now). I am not satisfied with the elution, the molecule does not advance...
  22. chem_tr

    A tough question

    I wanted to share a good question with you. It uses your redox chemistry skills as well as theoretical atomic valance calculation of organic substances. However, nobody managed to solve this problem as it is sufficiently time-consuming and somewhat difficult. Write the full-balanced equation...
Top