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Infra red and raman

The X-H stretching frequency in the IR (and Raman) spectrum is dependant on the identity of X, i.e., O-H = 3610 - 3640 cm -1 and N-H = 3400 - 3500 cm -1 . However, the ν(X-H) is shifted to lower energy (lower frequency) as a consequence of hydrogen bonding. In addition, while non-hydrogen bonded X-H stretches are sharp, the presence of hydrogen bonding results in the peak being broadened. Figure X demonstrates both these effects. The O-H stretch for dilute n BuOH in CCl 4 is a sharp peak at 3650 cm -1 due to the lack of hydrogen bonding between the two components ( [link] a), and the presence of hydrogen bonding between n BuOH and n BuOH is limited by the dilution. By contrast, a dilute solution of n BuOH in Et 2 O results in a shift to lower frequency and a significant increase of peak width ( [link] b) as a result of fairly strong O-H ... O bonds. Finally, a dilute solution of n BuOH in NMe 3 results in a further shift to 3250 cm -1 and a very broad peak ( [link] c). The broadening of the peaks is due to the distribution of X-H distances within a X-H ... Y hydrogen bond.

Schematic representation of the O-H stretch region in the IR spectra of a dilute solution of n BuOH in (a) CCl 4 , (b) Et 2 O, and (c) NEt 3 .

Nmr

The presence of hydrogen bonding results the shift to higher ppm (lower frequency) of the 1 H NMR resonance for the proton. This shift is due to the decrease in shielding of the proton. A dilute solution of n BuOH in CCl 4 shows a resonance typical of a non-hydrogen bonded compound ( [link] a), while that for n BuOH in NMe 3 ( [link] b) shows a significant low field shift. Very strong intra or intermolecular hydrogen bonded species show a very large 1 H NMR shift (e.g., [link] c).

Schematic representation of the relative shift of the O H resonance for (a) n BuOH in CCl 4 , (b) n BuOH in NEt 3 , and (c) concentrated acetic acid.

Effects of hydrogen bonding

Physical effects

The presence of intermolecular hydrogen bonding provides additional attractive forces between molecules. Thus, properties that depend on intramolecular forces are affected.

Liquids with significant hydrogen bonding exhibit higher boiling points, higher viscosity, and higher heat of vaporization (ΔH v ) as compared to analogous compounds without extensive hydrogen bonding. For solids the presence of hydrogen bonding results in an increase in the melting point of the solid and an increase in the associated heat of fusion (ΔH f ).

The archetypal case for the effect of hydrogen bonding is the melting and boiling points of the hydrides of the Group 16 elements, i.e., H 2 E. For a series of analogous compounds with the same molecular structure it would be expected that the boiling points would be related to the molecular mass. However, as can be seen from [link] , the melting and boiling points of water are anomalously higher than those of its heavier analogs. In fact from [link] it is clear that just considering H 2 S, H 2 Se, and H 2 Te, the expected trend is observed, and it is similar to that for the Group 14 hydrides (CH 4 , SiH 4 , etc). Therefore, water must have additional intermolecular forces as compared to its heavier homologs. This observation is consistent with the strong hydrogen bonding in water, and the very weak if nonexistent hydrogen bonding in the sulfur, selenium, and tellurium analogs.

Questions & Answers

Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
Jyoti Reply
I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
Damian
yes that's correct
Professor
I think
Professor
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
How we are making nano material?
LITNING Reply
what is a peer
LITNING Reply
What is meant by 'nano scale'?
LITNING Reply
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
Rafiq
if virus is killing to make ARTIFICIAL DNA OF GRAPHENE FOR KILLED THE VIRUS .THIS IS OUR ASSUMPTION
Anam
analytical skills graphene is prepared to kill any type viruses .
Anam
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
Adin
why?
Adin
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
research.net
kanaga
sciencedirect big data base
Ernesto
Introduction about quantum dots in nanotechnology
Praveena Reply
hi
Loga
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
Bharti
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Source:  OpenStax, Hydrogen. OpenStax CNX. Sep 28, 2009 Download for free at http://cnx.org/content/col10984/1.4
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