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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/10/14 15:35:30」(JST)

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Paraformaldehyde (PFA) is the smallest polyoxymethylene, the polymerization product of formaldehyde with a typical degree of polymerization of 8–100 units. Paraformaldehyde commonly has a slight odor of formaldehyde due to decomposition. Paraformaldehyde is a poly-acetal.

Synthesis

Paraformaldehyde forms slowly in aqueous formaldehyde solutions as a white precipitate, especially if stored in the cold. Formalin actually contains very little monomeric formaldehyde; most of it forms short chains of polyformaldehyde. A small amount of methanol is often added as a stabilizer to limit the extent of polymerization.

Reactions

Paraformaldehyde can be depolymerized to formaldehyde gas by dry heating^[1] and to form a formaldehyde solution by water in the presence of a base or heat. The very pure formaldehyde solutions obtained in this way are used as a fixative for microscopy and histology.

The resulting formaldehyde gas from dry heating paraformaldehyde is flammable.

Uses

Once paraformaldehyde is depolymerized, the resulting formaldehyde may be used as a fumigant, disinfectant, fungicide, and fixative. Longer chain-length (high molecular weight) polyoxymethylenes are used as a thermoplastic and are known as polyoxymethylene plastic (POM, Delrin). It was used in the past in the discredited Sargenti method of root canal treatment.^[2]

Paraformaldehyde is not a fixative; it must be depolymerized to formaldehyde in solution. In cell culture, a typical formaldehyde fixing procedure would involve using a 4% formaldehyde solution in phosphate buffered saline (PBS) on ice for 10 minutes.

Toxicity

As a formaldehyde releasing agent, paraformaldehyde is a suspected carcinogen.^{[citation needed]} Its acute oral median lethal dose in rats is 592 mg/kg.^{[citation needed]}

References

^ Yates, J (1973). "Adsorption and decomposition of formaldehyde on tungsten (100) and (111) crystal planes". Journal of Catalysis 30 (2): 260. doi:10.1016/0021-9517(73)90073-0.
^ http://www.dentalwatch.org/questionable/sargenti/overview.html

UpToDate Contents

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1. 末梢神経障害の評価のための皮膚生検 skin biopsy for the evaluation of peripheral nerve disease
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English Journal

Consistent and reproducible staining of glia by a modified Golgi-Cox method.

Gull S1, Ingrisch I1, Tausch S1, Witte OW1, Schmidt S2.
Journal of neuroscience methods.J Neurosci Methods.2015 Dec 30;256:141-50. doi: 10.1016/j.jneumeth.2015.08.029. Epub 2015 Sep 11.
BACKGROUND: Golgi-Cox staining is a powerful histochemical approach which has been used extensively to visualize the morphology of neurons and glia. However, its usage as a first-choice method is hindered by its uncertain nature, diminished consistency and lengthy staining duration. The FD Rapid Gol
PMID 26365333

Synthesis and structural characterization of monomeric and dimeric peptide nucleic acids prepared by using microwave-promoted multicomponent reactions.

Ovadia R1, Lebrun A, Barvik I, Vasseur JJ, Baraguey C, Alvarez K.
Organic & biomolecular chemistry.Org Biomol Chem.2015 Dec 7;13(45):11052-71. doi: 10.1039/c5ob01604e. Epub 2015 Sep 23.
A solution phase synthesis of peptide nucleic acid monomers and dimers was developed by using microwave-promoted Ugi multicomponent reactions. A mixture of a functionalized amine, a carboxymethyl nucleobase, paraformaldehyde and an isocyanide as building blocks generates PNA monomers which are then
PMID 26394794

Immunolocalization of MMP 2, 9 and 13 in prednisolone induced osteoporosis in mice.

Sun B1, Sun J1, Han X1, Liu H1, Li J1, Du J1, Feng W1, Liu B1, Cui J1, Guo J1, Amizuka N2, Li M3.
Histology and histopathology.Histol Histopathol.2015 Dec 4:11702. [Epub ahead of print]
Long-term use of glucocorticoids (GC) causes rapid bone loss and increases the risk of osteoporotic fractures. Matrix metalloproteinase (MMPs), the most prominent kind of proteases implicated in the proteolytic degradation of the extracellular matrix (ECM), have been reported to be involved in patho
PMID 26636416

Japanese Journal

Phosphomethylated Polyethyleneimine-immobilized Chelating Resin: Role of Phosphomethylation Rate on Solid-Phase Extraction of Trace Elements

KAGAYA Shigehiro,IKEDA Ryo,KAJIWARA Takehiro,GEMMEI-IDE Makoto,INOUE Yoshinori
Analytical Sciences 35(4), 413-419, 2019
… Chelating resins immobilizing phosphomethylated polyethyleneimine (PM-PEI) with different phosphomethylation (PM) rates were prepared by using different amounts of both phosphonic acid and paraformaldehyde in the phosphomethylation of PEI immobilized on a methacrylate resin as a base resin. …
NAID 130007629977

ラット正常歯髄におけるLYVE-1陽性マクロファージはCD163を発現する

田澤建人,川島伸之,草野雅彦,池田英治,興地隆史
日本歯内療法学会雑誌 40(1), 7-13, 2019
… The maxilla, gingiva, small intestine, and spleen were collected from male SD rats (8-9 weeks old, n=4) and fixed with 4% paraformaldehyde. …
NAID 130007594626

Methodological improvement of fluorescein isothiocyanate peanut agglutinin (FITC-PNA) acrosomal integrity staining for frozen-thawed Japanese Black bull spermatozoa

RAJABI-TOUSTANI Reza,AKTER Quzi Sharmin,ALMADALY Essam A.,HOSHINO Yoichiro,ADACHI Hiromichi,MUKOUJIMA Koushi,MURASE Tetsuma
Ｔｈｅ　Ｊｏｕｒｎａｌ　ｏｆ　Ｖｅｔｅｒｉｎａｒｙ　Ｍｅｄｉｃａｌ　Ｓｃｉｅｎｃｅ, 2019
… Spermatozoa were washed, fixed with 1–3% paraformaldehyde (PFA) in suspension for 10, 20, and 30 min, permeabilized with 0–2% Triton X-100 for 5 min, stained with FITC-PNA, and mounted with different antifade agents (0.22 M 1,4-diazabicyclo [2,2,2] octane (DABCO), SlowFade®, and ProLong®) in suspension (In-suspension) or on a smear (On-smear). … The results of experiment 3 showed that the paraformaldehyde concentration used for a 30 min fixation could be reduced from 3 to 2%. …
NAID 130007541827

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★リンクテーブル★

リンク元	「パラホルムアルデヒド」

「パラホルムアルデヒド」

Paraformaldehyde
Names
	IUPAC name Polyoxymethylene
Identifiers
CAS Registry Number	30525-89-4
ChemSpider
PubChem	24898648
Properties
Chemical formula	OH(CH2O)nH (n = 8 - 100)
Appearance	white crystalline solid
Density	1.42 g·cm−3 (25 °C)
Melting point	120 °C (248 °F; 393 K)
Solubility in water	low
Hazards
Safety data sheet	Oxford MSDS
EU classification	Toxic (T); Corrosive (C)
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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	Infobox references

　　[★]

英: paraformaldehyde
ラ: paraformaldehydum
関: ホルムアルデヒド

[1] Yates, J (1973). "Adsorption and decomposition of formaldehyde on tungsten (100) and (111) crystal planes". Journal of Catalysis 30 (2): 260. doi:10.1016/0021-9517(73)90073-0.

[2] ttp://www.dentalwatch.org/questionable/sargenti/overview.html

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paraformaldehyde