The Hive > Newbee Forum

Sulfate salt

(1/3) > >>

wolfx:
I think in the hydrochloride salt, the hydrogen in the HCl forms a hydrogen bond with the nitrogen in the MDMA molecule, correct ?

Now, I am not sure what kind of bond it is formed in the sulfate salt. BTW, is it written 2(MDMA).SO4, is this correct ? Is it a normal covalent bond ? ( I don't think so )

indole_amine:
Both HCl and sulfate salt are complex salts, meaning their ions aren't held together by the usual ionic forces but rather just by weak forces like dipole/dipole or van-der-waals or (in this case) H-bridge bonds. This kind of intermolecular force can be seen with molecules containing N or O bearing one ore more hydrogens (like NH2 for example).

Therefore, the correct formula are:

MDMA*HCl   or   (MDMA)2*H2SO4

(each hydrogen from the acid attracts one amine nitrogen, which becomes partially positive, depicted through "delta+" at the nitrogen and "delta-" at the hydrogen bearing counterpart, i.e. Cl or SO4)

Because the hydrogen bond is rather weak compared to electron sharing bonds, complex salts are usually not very stable, compared to ionic bonds (like with NaCl) or electron sharing bonds (which are called covalent bonds).


indole_amine

hypo:
> Both HCl and sulfate salt are complex salts, meaning their ions aren't
> held together by the usual ionic forces but rather just by weak forces
> like dipole/dipole or van-der-waals or (in this case) H-bridge bonds.

wtf? i have never heard of this.
of course it's ionic forces between MDMAH+ and Cl- resp. MDMAH+ and HSO4- or SO4--.

could you please provide a pointer detailing the "complex salt"-thingy? textbook
or otherwise? i think you are confusing this with hydro-complexes as in CaSO4.2H2O.
(those aren't H-bridges either, but dative bonds)

ps: for a great book about bonds, complexes and all that stuff, check out
"Inorganic Chemistry: Principles of Structure and Reactivity" by Huheey.
very recommended.

indole_amine:
"Hydrogen Bonding
A hydrogen bond is not a covalent bond but a particularly strong transient dipole-dipole interaction. A hydrogen atom can participate in hydrogen bonding if it is linked covalently to an electronegative atom such as oxygen, nitrogen or fluorine. Hydrogen bonding is a strong intermolecular interaction, requiring ~5kcal mol-1 to break (c.f. ~100kcal mol-1 required to break a C–H or N–H covalent bond). Hydrogen bonding is replete in nature (i.e. DNA base pairing) and has a large effect upon the physical properties of organic compounds."

from http://users.ox.ac.uk/~mwalter/web_04/year1/intro/forces.htm
(utf google..)


Also good:
 
http://itl.chem.ufl.edu/2045/lectures/lec_g.html

http://www.uni-giessen.de/chemie/vorlesung/einfuehrung_oc/4000main.htm

http://onsager.bd.psu.edu/~jircitano/IMforces.html



indole_amine

indole_amine:
"An Intriguing Hydrogen Bond Pattern in a Maleate Salt. Connie G. Chidester, Michael S. Bergren and Richard F. Heier, Pharmacia & Upjohn, Kalamazoo, MI

PNU-95666E is a dopamine D 2 agonist currently in Phase II Clinical trials for acute treatment of Parkinson’s disease. Although during several years of preclinical testing it was widely perceived in the research community as an important and interesting compound, it was unusually difficult to crystallize and the crystal structure was done only recently. PNU-95666E is the (R) isomer of a methylamino-imidazoquinolinone, (5-(methylamino)-5,6-dihydro-4H-imidazo {4,5,1-ij} quinolin-2(1H)-one). The (R)-dipropylamino analog PNU-86170 crystallizes readily as either the free base or a salt and a crystal structure had been done of the hydrobromide. However, suitable crystals of the free base of PNU-95666 could not be obtained, and of the many salts tried, including hydrochloride, hydrobromide, fumarate, maleate and various hydrates of these, only the maleate salts seemed at all amenable to crystallization. After considerable effort, diffraction quality crystals were eventually obtained of the maleate.

The crystal structure is triclinic, spacegroup P1, with two molecules in the asymmetric unit and an equal number of maleic acid molecules. The hydrogen bonding pattern is complex and beautiful and offers many clues toward understanding why the compound was so difficult to crystallize and why the maleic acid salt was the key to crystallization. Hydrogen bonding patterns involving maleates in other crystal structures are compared."

(http://www.hwi.buffalo.edu/ACA/ACA99/abstracts/text/W0237.html)


indole_amine

Navigation

[0] Message Index

[#] Next page