FORMALDEHYDE Bacioiu Bogdan
Basic Information about Formaldehyde
Simplest aldehyde, chemical formula HCHO. Formaldehyde (37%) in water solution (formalin) is used as a preservative, embalming agent, and disinfectant. Large amounts of formaldehyde are used in the manufacture of various familiar plastics: Bakelite (the first plastic) is the trademark name for formaldehyde and phenol polymer; Formica is the trademark name for formaldehyde and urea polymer. The reaction of formaldehyde with proteins (called amino formylation) leads to its use in the tanning industry and for treating various vegetable proteins to render them fibrous.
The Physical Properties of Formaldehyde
* The chemical formula for formaldehyde is CH2O and the molecular weight is 30.03 g/mol. (1)
* The vapor pressure for formaldehyde is 10 mm Hg at -88 EC, and its log octanol/water partition coefficient (Log Kow) is -0.65. (1)
* Formaldehyde is a colorless gas with a pungent, suffocating odor at room temperature; the odor threshold for formaldehyde is 0.83 ppm. (1,8)
* Formaldehyde is readily soluble in water at room temperature. (1)
* Commercial formaldehyde is produced and sold as an aqueous solution containing 37 to 50 percent formaldehyde by weight. (1)
· Vapor Pressure: 52mm @ 37° C
· Specific Gravity: 1.083
· Vapor Density: 1.03
· Appearance: colorless liquid
· Carbon Monoxide
· Carbon Dioxide
Fire Hazard Data
· Flash point: 310° F (154°C)
· Autoignition Temp: 932° F (499° C)
· Extinguishers: Water spray, Carbon dioxide, dry chemical powder or appropriate foam.
· Special Procedures: Wear self-contained breathing apparatus and protective clothing to prevent contact with skin and eyes, wear rubber gloves.
· Unusual Fire hazards: Emits toxic fumes under fire conditions.
· Evacuate area.
· Wear self-contained breathing apparatus, rubber boots and heavy rubber gloves.
· Cover with lime or soda ash and place in closed containers for disposal.
· Ventilate area and wash spill site after material pickup is complete.
· Combustible Liquid
· Dissolve or mix the material with a combustible solvent and burn in a chemical incinerator equipped with an afterburner and scrubber.
· Observe all federal, state, and local environmental regulations.
Formaldehyde - H2C=O
Atomic Charges and Dipole Moment
C1 charge= 0.358
H3 charge= 0.020
H4 charge= 0.020
with a dipole moment of 2.46866 Debye
between C1 and O2: distance=1.220 ang___ between C1 and H3: distance=1.122 ang___
between C1 and H4: distance=1.122 ang___
for H3-C1-O2: angle=121.7 deg___ for H4-C1-O2: angle=121.8 deg___
Bond Orders (Mulliken):
between C1 and O2: order=1.870___ between C1 and H3: order=0.940___
between C1 and H4: order=0.940___
Best Lewis Structure
The Lewis structure that is closest to your structure is determined. The hybridization of the atoms in this idealized Lewis structure is given in the table below.
Hybridization in the Best Lewis Structure
1. A bonding orbital for C1-O2 with 1.9999 electrons
__has 32.04% C1 character in a p-pi orbital ( 99.45% p 0.55% d)
__has 67.96% O2 character in a p-pi orbital ( 99.81% p 0.19% d)
2. A bonding orbital for C1-O2 with 1.9994 electrons
__has 34.65% C1 character in a sp1.84 hybrid
__has 65.35% O2 character in a sp1.49 hybrid
3. A bonding orbital for C1-H3 with 1.9932 electrons
__has 56.45% C1 character in a sp2.04 hybrid
__has 43.55% H3 character in a s orbital
4. A bonding orbital for C1-H4 with 1.9932 electrons
__has 56.45% C1 character in a sp2.04 hybrid
__has 43.55% H4 character in a s orbital
7. A lone pair orbital for O2 with 1.9870 electrons
__made from a sp0.65 hybrid
8. A lone pair orbital for O2 with 1.9069 electrons
__made from a p-pi orbital ( 99.92% p 0.08% d)
-With core pairs on: C1 O2 -
Donor Acceptor Interactions in the Best Lewis Structure
The localized orbitals in your best Lewis structure can interact strongly. A filled bonding or lone pair orbital can act as a donor and an empty or filled bonding, antibonding, or lone pair orbital can act as an acceptor. These interactions can strengthen and weaken bonds. For example, a lone pair donor->antibonding acceptor orbital interaction will weaken the bond associated with the antibonding orbital. Conversly, an interaction with a bonding pair as the acceptor will strengthen the bond. Strong electron delocalization in your best Lewis structure will also show up as donor-acceptor interactions. Interactions greater than 20 kJ/mol for bonding and lone pair orbitals are listed below.
The interaction of the second lone pair donor orbital, 8, for O2 with the antibonding acceptor orbital, 59, for C1-H3 is 114. kJ/mol.
The interaction of the second lone pair donor orbital, 8, for O2 with the antibonding acceptor orbital, 60, for C1-H4 is 114. kJ/mol.
Molecular Orbital Energies
The orbital energies are given in eV, where 1 eV=96.49 kJ/mol. Orbitals with very low energy are core 1s orbitals. More antibonding orbitals than you might expect are sometimes listed, because d orbitals are always included for heavy atoms and p orbitals are included for H atoms. Up spins are shown with a ^ and down spins are shown as v.
12 ----- 3.090 11 ----- 2.598 10 ----- 1.808 9 ----- -2.949 8 -^-v- -6.276 7 -^-v- -10.19
6 -^-v- -10.98 5 -^-v- -12.14 4 -^-v- -15.60 3 -^-v- -26.43 2 -^-v- -269.1 1 -^-v- -507.0
Total Electronic Energy
The total electronic energy is a very large number, so by convention the units are given in atomic units, that is Hartrees (H). One Hartree is 2625.5 kJ/mol. The energy reference is for totally dissociated atoms. In other words, the reference state is a gas consisting of nuclei and electrons all at infinite distance from each other. The electronic energy includes all electric interactions and the kinetic energy of the electrons. This energy does not include translation, rotation, or vibration of the molecule.
Total electronic energy = -114.5456831412 Hartrees
The Photoproduction of Organic Residues in Laboratory Interstellar Ice Analogs
UV (Ultraviolet) radiation probably causes significant photochemistry within the mixed-molecular ices found in space. We simulate this process in our laboratory using some high-tech gadgetry. When we simulate the photochemistry of interstellar and cometary ices in the lab we make a host of organic compounds (i.e. compounds composed primarily of carbon, the kinds of molecules from which we and all living things are made). We believe this process may be responsible for the richness of the organics seen in the Diffuse and Dense Interstellar Medium, comets, and meteorites.
Many people believe that organic compounds from comets and asteriods helped to make life on Earth possible, so some of these compounds have potential implications for the origin of life on the Earth.
Since comets and interstellar ices are composed primarily of water we started with ices of water and other simple compounds known to be in space like methanol (CH3OH), carbon monoxide (CO) and ammonia (NH3). From such simple starting materials we were able to make things like methane (CH4), carbon dioxide (CO2), ethanol (CH3CH2OH), formamide, acetamide, ketones, and alcohols. After these sun-burnt ices are warmed up and the volatiles sublime away we were able to detect some larger compounds like polyoxymethylene - based polymers (POMs), and hexamethylene tetramine (HMT). A number of these compounds have potential implications for the origin of life on the Earth. For example, hexamethylenetetramine (HMT; C6H12N4) is a potential source of formaldehyde and ammonia and the acid hydrolysis of HMT leads to the production of amino acids. Follow these links to see how we identified HMT and how we think it formed.
More Complex Organic Compounds
Even though HMT and POM have molecular weights over 100 amu these are just the smaller compounds. There are much larger organic materials produced when we perform our interstellar/cometary ice simulations. Gas Chromatograph Mass Spectrometry (GCMS) and Laser Desorption Mass Spectrometry analyses (Richard Zare's Lab) of our residues show the presence a hundreds of different compounds, most of which have yet to be identified. Many of these compounds have properties that are potentially of interest to issues associated with the origin of life. For example, some of these compounds fluoresce, others spontaneously form membranes in solution, and so on. To learn a little more about these compounds, click here.
PAH-related photoproducts (alcohols, ketones, and Hn-PAHs, etc.)
Polycyclic aromatic hydrocarbons (PAHs) represent one of the most abundant forms of carbon in the interstellar medium. Since most PAHs are relatively non-volatile compounds, in dense interstellar clouds they are expected to feeze out into the ice. Indeed, astronomers (such as Kris Sellgren of Ohio State and Jean Chiar of NASA Ames) have directly observed PAHs frozen into the ices. Since we know that PAHs will be photoprocessed like all the other molecules in the ices we studies the photolysis of PAHs in H2O-rich ices and this resulted in a Science paper (see below). These experiments showed that photoprocessing of PAHs in water ice leads to the production of a number of new compounds including aromatic ethers, alcohols, and ketones as well as PAHs that contain excess peripheral H atoms (Hn-PAHs). These kinds of compounds are all seen in carbon-rich meteorites and we believe that ice photochemistry is the source of these compounds. Furthermore, Hn-PAHs explain the infrared emssion at 3.4 microns seen towards energetic environments such as the Orion Bar (Bernstein, Sandford, & Allamandola, ApJ see below) The production of quinones is of particular interest since this class of compounds includes important biomolecules such as the K vitamins which play a key role in electron transport in living systems.
A Direct Method for Sequencing of Genomic DNA using PCR from Frozen Tumor Tissue
Often there is a need for DNA testing on small tissue samples that have been embedded in OPT.
A) Sample Preparation
1. After thawing at room temperature, the excess embedding material is removed and the
sample ground using an autoclaved and cleaned mortar and pestle with 1 ml PBS (phosphate
2. The mixture is then added to 1 ml of a 2x lysis buffer (Applied Biosystems, Foster City,
CA) that was preincubated for 10 minutes at 60 °C.
3. Proteinase K is added to a final concentration of 0.1 mg/ml and incubated overnight at 60 °C with gentle mixing.
4. Genomic DNA was extracted with two washings of phenol-chloroform-isoamyl alcohol (25:24:1) and ethanol/salt precipitation at room temperature for 60 minutes with each wash.
5. The supernatant is poured off and the pellet was washed with 70% ethanol.
6. The tubes are placed in a centrifugal concentrator and evaporated to dryness.
7. The DNA pellet is resuspended in 10 mM Tris, pH 8.0 and 1 mM EDTA (TE Buffer).
8. Two micrograms DNA are subjected to PCR amplification in 100 µl reaction mixture
containing 50 pmol primers, 200 µM dNTP, 50 MM KCl, 10 mM Tris-HCl pH 8.3, 1.5 mM MgCl2, 0.01% gelatin and 2.5 U Taq DNA polymerase.
9. Mineral oil is laid over the top to prevent evaporation, and the solution is subjected to
30 cycles of denaturation (94 °C, 1 minute), primer annealing (at calculated temperature
1.5 minutes) and primer extension (72 °C, 2 minutes) in a thermal cycler.
10. Primers are derived from the p53 gene.
11. Amplification is preceded by denaturation at 94 °C for 1.5 minutes and followed by
extension at 72 °C for 7 minutes.
12. Upon completion of amplification, the sample is extracted once with 100 µl chloroform.
13. A 10 µl sample is then electrophoresed using a 1% agarose gel.
Sun, Yi, Hegamyer, Glenn and Colburn, Nancy H. National Cancer Institute, Frederick Cancer Research and Development, Frederick, Maryland. "A simple method using PCR for Direct Sequencing of Genomic DNA from Frozen Tumor Tissue Embedded in Optimal Cutting Temperature Compound."
The Use of Centrifugal Concentrators for HPLC Work with Isocyanates
Centrifugal concentrator concentrates samples quickly with a minimal amount of handling and emission to the air.
Three traps are used to protect the vacuum pump. The first is a refrigereated cold trap (-90° C), the second is a liquid nitrogen (<-100 °C) and the third is a chemical trap.
B) Isocyanates Preparation
1. Toluenediisocyanate (TDI) is analyzed using the methods by Hakes in "An Improved HPLC
Method for the Determination of Isocyanates Using Nitro Reagent."
2. Samples are prepared by adding TDI standards at three concentration levels to nitro
reagent (N-4 ntirobenzyl N-n propylamine in toluene).
3. The samples are mixed and the toluene is removed using the concentrator.
4. After evaporation, 2 ml methylene chloride are added and samples are extracted with
1 ml 0.5 M HCl before injection into the HPLC.
C) HPLC Conditions
1. Flow rate at 1.0 ml/minute.
2. Mobile phase 50% hexane, 47.5% methylene chloride, and 2.5% methanol.
3. Run time is 7 minutes.
4. Oven temperature at 40 °C.
5. U.V. detection at 245 nm.
6. Column Silica 5 µ , 25 cm x 4.6 mm (Dupont, Wilmington, Delaware).
Gaylord, Anna Maria. "Use of Automated Centrifugal Evaporator in Preparation of HPLC Sample Extracts," American Environmental Laboratory, 46-49 (October, 1990).
Hakes, D. C. Johnson, G. D., and Marhevka, J. S. "An improved HPLC Method for the Determination of Isocyanates Using `Nitro Reagent'," American Industrial Hygiene Association Journal 47(3), 181-184 (1986).
The Use of Centrifugal Concentrators for HPLC Work with Formaldehyde
Centrifugal concentrator concentrates samples quickly with a minimal amount of handling and emission to the air.
Three traps are used to protect the vacuum pump. The first is a refrigerated cold trap (-90 °C), the second is a liquid nitrogen trap (<-100 °C), the third is a chemical trap.
B) Formaldehyde Preparation
1. The analysis is done using the EPA, "Method for the determination of aldehydes and ketones in ambient air using HPLC, method TO5".
2. Samples are prepared by adding formaldehyde and formaldehyde-dinitrophenylhydrazine
derivative standards at three concentration levels to 10 ml DHPH reagent and 10 ml
3. The samples are mixed and the isooctane layer is removed and saved.
4. The DNPH layer is then extracted with
5. The sample is mixed and spun and the methylene chloride-hexane levels removed and
mixed with the isooctane in step 3.
6. This sample is placed in the CentriVap and evaporated to dryness.
7. After evaporation, 5 ml methanol is added and the sample analyzed by HPLC.
C) HPLC Conditions
1. Flow rate at 1.0 ml/minute.
2. Mobile phase: 80% methanol, 20% water.
3. Run time: 10 minutes.
4. Oven temperature at 35 °C.
5. U.V. detection at 370 nm.
6. Column Zorbax*, C18 5 µ , 25 cm x 4.6 mm (*Registered trademark of E. I. duPont de
Nemours, Wilmington, Delaware).
Gaylord, Anna Maria. "Use of Automated Centrifugal Evaporator in Preparation of HPLC Sample Extracts," American Environmental Laboratory, 46-49 (October, 1990). EPA, "Method for the determination of aldehydes and ketones in the ambient air using HPLC, method TO5."
Recovery of Tetrachlorodibenzodioxin and Furans Using the CentriVap Mobile Console
Using a CentriVap aids in the evaporation and recovery of samples.
1. Place 10 ml toluene into five 50 ml centrifuge tubes.
2. Add 200 nG of the sample to be tested.
3. Mix and place tubes into rotor in the concentrator.
4. Start condenser and let run for 30 minutes.
5. Close lid and start rotor. Turn on heater.
6. Start vacuum pump. Controls are set at concentrator vacuum and auxiliary vent.
7. After 15 minutes, turn concentrator control to backfill When vacuum is released and rotor is stopped, open lid and check samples. If more drying is needed, repeat steps 5-7.
8. Add 1 ml toluene to vial, cap and vortex. Let stand for 2 minutes and place 10 µl 200 nG/l internal standard.
9. Prepare standard by adding 200 nG of 2, 3, 7, 8-tetrachlorodibenzofuran-13C and 200 nG
of 1, 2, 3, 7: 1, 2, 3, 8-tetrachlorodibenzodioxin to 1 ml toluene. Place 10 µl of this standard into a micro-autosampler vial and add 10 µl of the 200 nG/ml of internal standard.
10. Analyze by high resolution mass spectroscopy.
C. S. Parsons, Senior Chemist, Pacific Analytical, Inc., Carlsbad, California
Carbon-carbon coupling from formaldehyde reaction on Mo(110).
Formaldehyde (CH2O) reaction on Mo(110) is studied with temperature programmed reaction and IR reflectance absorbance spectroscopy. We present preliminary results which demonstrate the evolution of gas-phase ethylene from the formaldehyde reaction, to the best of our knowledge the first example of carbon-carbon bond formation on clean Mo(110). This reaction is proposed to proceed via an ethylene dialkoxide intermediate, analogous to that formed during reaction of ethylene glycol on Mo(110). Other reactions include hydrogenation of CH2O to form a methoxy intermediate which subsequently undergoes C-O bond scission to evolve gas-phase Me radicals at .apprx.600 K.
An important reaction of Formaldehyde is the one for the preparation of Alcohols when it reacts with R*-MgCl to form an alcohol:
* (R represents an alkane)
R-MgCl + CH2O Þ H – C – OH
Around 1872, various workers were studying the reactions of phenol with, among other materials, formaldehyde. The reactions appeared to be difficult to control and the outcome of the reactions difficult to reproduce.
Between 1900 and 1905 these reactions were investigated again and found to produce product(s) that ranged in consistency from very sticky, viscous liquids to hard, resinous solids.
In due course, it was recognised that the former could be used as a substitute for shellac in varnishes while the latter could replace gutta-percha or ebonite.
In 1907, Leo Bakeland established that the reaction between phenol and formaldehyde was sensitive to the relative concentrations of the starting materials, pH and temperature. In the same year he filed his first patent on phenol-formaldehyde resins which he called Bakelite.
Two years later he filed a patent on the incorporation of mineral fillers in a resin to form a moulding compound. Altogether, he filed 199 patents.
At the same time Bakeland was engaged on his work on phenol-formaldehyde reactions, an eminent British chemist, James Swinburn , was working in the same field, and , in due course, he reached the same conclusions. However he filed his patent one day after Bakeland's.
The Bakelite company was established in 1926 with Bakeland and Swinburn in partnership.
The Uses of Formaldehyde
* Formaldehyde is used predominantly as a chemical intermediate. It also has minor uses in agriculture, as an analytical reagent, in concrete and plaster additives, cosmetics, disinfectants, fumigants, photography, and wood preservation. (1,2)
* Formaldehyde (as urea formaldehyde foam) was extensively used as an insulating material until 1982 when it was banned by the U.S. Consumer Product Safety Commission. (1,2)
Health Data from Inhalation Exposure
Regulatory, advisory numbersb
* LC50 (mice) (400 mg/m3)
* LC50 (rats) (203 mg/m3)
* OSHA PEL (4.5 mg/m3)
* ACGIH TLV (1.5 mg/m3)
* USEPA Cancer Risk Level (1-in-a-million excess lifetime risk) = 8 H 10-5 mg/m3
ACGIH TLVCAmerican Conference of Governmental and Industrial Hygienists' threshold limit value expressed as a time-weighted average; the concentration of a substance to which most workers can be exposed without adverse effects.
LC50 (Lethal Concentration50)CA calculated concentration of a chemical in air to which exposure for a specific length of time is expected to cause death in 50% of a defined experimental animal population.
OSHA PELCOccupational Safety and Health Administration's permissible exposure limit expressed as a time-weighted average; the concentration of a substance to which most workers can be exposed without adverse effect averaged over a normal 8-h workday or a 40-h workweek.
a Health numbers are toxicological numbers from animal testing or risk assessment values developed by EPA.
b Regulatory numbers are values that have been incorporated in Government regulations, while advisory numbers are nonregulatory values provided by the Government or other groups as advice.
Exposure to Formaldehyde
In 1980, laboratory findings showed that exposure to formaldehyde could cause nasal cancer in rats. Since then, the question of whether exposure to formaldehyde increases a person's risk of cancer has been the subject of considerable controversy.
Early concerns focused on the use of formaldehyde in the manufacture of mobile homes. Soon, however, questions were raised about workers routinely exposed to the substance: anatomists, embalmers, phatologists, other medical workers, and industrial workers who produce formaldehyde (and formaldehyde resins and plastics), plywood, photographic film, and permanent press fabrics.
During the 1980s, many studies, including major ones by the National Cancer Institute (NCI), were conducted to determine whether these workers had a greater risk for developing cancer than people in the general population. Much of this research was intended to help two regulatory agencies, the Environmental Protection Agency (EPA) and the Occupational Safety and Health Administration (OSHA), develop regulations, if necessary, to protect the public and workers from unnecessary risks of cancer because of formaldehyde exposure. Investigations at NCI have focused on industrial workers and professionals such as anatomists and embalmers. Results from these two groups were not consistent. Anatomists and embalmers were at greater risk for leukemia and brain cancer than the general population, but industrial workers were not. Industrial workers employed in the chemical, plastics, plywood, and photographic film industries developed nasopharyngeal cancer more often than the general population. The risk increased sevenfold for workers with heavy exposure to formaldehyde and formaldehyde-containing particulates. Studies in the Netherlands and Denmark have shown elevated rates of nasal cancer in many persons exposed to formaldehyde.
An NCI study that noted a 30-percent increase in lung cancer mortality among industrial workers generated the most controversy because the rate of lung cancer did not increase with the level of exposure. The excess was not evident at all industrial plants and was confined to workers in resin and molding compound production. This led NCI investigators to conclude that factors other than formaldehyde might have been involved. Other scientists believe formaldehyde exposure may be the cause of the lung cancer excess.
By 1987, EPA classified formaldehyde as a "probable human carcinogen” under conditions of unusually high or prolonged exposure. The International Agency for Research on Cancer also concluded that formaldehyde is a probable human carcinogen. The OSHA and EPA concluded that new rules governing exposure limits were necessary. In November 1987, OSHA proposed that the occupational standard for formaldehyde exposure be reduced from 3 parts per million (ppm) to 1 ppm, averaged over an 8-hour workday; this proposal became law the following month. In May 1992, the law was amended, and the formaldehyde exposure limit was reduced to 0.75 ppm. (Information is available from the Occupational Safety and Health Administration, Public Affairs Office, Room N3647, 200 Constitution Avenue, NW., Washington, DC 20210. You may also contact the Public Affairs Office by calling 202–693–1999.)
Formaldehyde use also has been studied in nonindustrial settings. In February 1982, the Consumer Product Safety Commission (CPSC) ordered a ban on all sales of urea formaldehyde foam insulation (UFFI) for homes and schools. The CPSC ruled that because formaldehyde gas often is released from foam after installation, UFFI presents an "unreasonable health risk." In April 1983, however, a Federal appellate court struck down this ban. The court ruled that there was not sufficient scientific evidence to justify the ban. The CPSC still believes that the evidence shows that risks are associated with UFFI. However, CPSC officials advise consumers to leave insulation alone if they have not experienced any health problems.
Please Note: The main sources of information for this fact sheet are EPA's Health and Environmental Effects Profile for Formaldehyde and the Integrated Risk Information System (IRIS), which contains information on oral chronic toxicity and the RfD, and the carcinogenic effects of formaldehyde including the unit cancer risk for inhalation exposure. Other secondary sources include the Hazardous Substances Data Bank (HSDB), a database of summaries of peer-reviewed literature, and the Registry of Toxic Effects of Chemical Substances (RTECS), a database of toxic effects that are not peer reviewed.
* The highest levels of airborne formaldehyde have been detected in indoor air, where it is released from various consumer products. One survey reported formaldehyde levels ranging from 0.10 to 3.68 ppm in homes. (1)
* Formaldehyde has also been detected in ambient air; the average concentrations reported in U.S. urban areas were in the range of 11 to 20 ppb. The major sources appear to be power plants, manufacturing facilities, incinerators, and automobile exhaust emissions. (7)
* Smoking is another important source of formaldehyde. (1)
* Formaldehyde may also be present in food, either naturally or as a result of contamination. (1)
Assessing Personal Exposure
* Blood levels of formaldehyde can be measured. However, these measurements only appear to be useful when exposure to relatively large amounts of formaldehyde has occurred. (2)
Health Hazard Information
* The major toxic effects caused by acute formaldehyde exposure via inhalation are eye, nose, and throat irritation and effects on the nasal cavity. (1,2)
* Other effects seen from exposure to high levels of formaldehyde in humans are coughing, wheezing, chest pains, and bronchitis. (1,2)
* Ingestion exposure to formaldehyde in humans has resulted in corrosion of the gastrointest