• Density:
1.284 g/cm3 Pred.
1.36 g/cm3
1.28±0.1 g/cm3 ****

1.36 g/cm3
1.28 g/cm3

  • Flash Point:
47.417 °C Pred.
47.4±22.6 °C Pred.

47.4 °C

  • Melting Point:
145.5 °C
146 °C
144-147 °C

146 °C

  • Boiling Point:
155 °C
154.792 °C Pred.
154.8±23.0 °C Pred.

154.8 °C

  • Water solubility:
2.75 mg/mL (20 °C)
275 g/L

1 g/5 ml water
275 g/L

List and describe three analytical techniques to characterize the organic compounds.

1. Mass Spectroscopy:
Mass spectrum shows as a vertical line graph, and each line represents an ion (or a fragment) which has a specific mass to charge ratio (m/z) and the height of each peak means the abundance of the ion. Generally the highest peak called base peak, and the peak has largest m/z ratio usually gives the total molecular weight of a compound. Difference between m/z ratios of two peaks refers to molecular weight of the fragment of this compound.
2. Infrared:
IR spectra indicate the presence of a band at a characteristic location (frequently is used to determine functional groups), usually for an IR adsorption or give a band there must be a changing in dipole moment. The intensity (weak, medium or strong), shape (broad or sharp) and position ((cm-1) are very important source for identify the functional groups in the spectra.
3. Nuclear magnetic resonance:
NMR Spectroscopy generally has proton NMR spectrum and carbon-13 NMR spectrum. Proton NMR shows different types of signals, what type of proton, number of proton in each type and connectivity of each group due to coupling neighboring groups that a compound contains. For Carbon-13 NMR, we can see the number of peaks which indicates the number of types of carbon and chemical
shift of each signal represents types of carbon of a compound
but usually we can't see the carbon-carbon coupling in carbon 13 spectra.
Example: Acetic Acid (CH3COOH):
  • Assignment 2

Article: Water-Stabilized Cavitands

Adel Rafai Far, Alexander Shivanyuk, and Julius Rebek, Jr, J.AM.CHEM.SOC. 2002,124, 2854-2855

DOI: 10.1021/ja012453p

[Full Marks JCB]

1. It talks about what is conformation of cavitands, and in this paper the additional of different features of the new cavitands can be resulted in kinetically stable inclusion on the NMR time scale.(Figure above)
2. How to synthesis the tetrabenzimidazol (figure above) which is the important compound in this article.
3. Tetrabenzimidazol have formation of hydrogen-bonded so it exists in the water-saturated CDCl3 under prediction and experimental results which is different from the energy minimized structure result( figure below ).
4.The vase conformation of originally Cavitands are rigid and not soluble in CDCl3 even with increasing the temperature, but with addition of small amounts of alcohols, it dissolves in CDCl3, proton NMR can approve this.
5.Several experiments don't show cavitand 4 and 5 exist as dimeric capsule that not match the pattern of hydrogen bonds presented in four imidazole part of cavitand 4.However, the same experiment shows that cavitand 6 not only have dimeric structure but also have much bigger size and stronger bond than cavitand 4 and 5.
6.Structure B and structure C is expected to have the similar properties since they almost have the same size of cavity. Cavitand 4 and it derivatives by tetramethylphosphonium bromide( 7a+Br-, figure above) has 1:1 stoichiometry, 7a+Br- is kinetically stable on the NMR time scale but has low solubility in CDCl3.
7.Even with kinetically stable 1:1 complex between cavitands, some of them have no interact with others under the same conditions
8.In either dry or water-saturated CDCl3 cavitand 5 can form a kinetically stable 1:1 complex with 7a+Br- as well, but with addition of methanol that increasing the polarity will destruct the complexes of cavitands.
9.Cavitand 4 ( figure above) is the new feature open-ended host that inside can trap alkene and outside is hydrophilic, also hydrogen bond from water shows solvent effects on simple cavitands.

Final Project

[please create a new page for your final project JCB]