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🏛 | To the end of the year zero disaster Director-general Pato Kyoto Labor Bureau


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To zero disaster at the end of the year Director General Site Pato Kyoto Labor Bureau

 
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As priority items, we confirmed fall prevention measures and handling of organic solvents.
 

The Kyoto Labor Bureau (Director-General of Yoshiyuki Kinashi) is in charge of preventing occupational accidents in the construction industry, which is feared to occur frequently at the end of the year. → Continue reading

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Fall prevention measures

solvent

solvent(Solvent,British: solvent) Is the name of a substance that dissolves other substances.

IndustrialIn the fieldsolventOften called (Yozai).

Overview

Most commonly usedWedIn addition,alcohol,acetone,Hexanelikeorganic matterAre often used, especially theseOrganic solvent (Organic solventCalled.

What is dissolved in the solventSoluteIt is called (solute), and the solvent and solute are combined.SolutionIt is called (solution).

As a solvent, dissolve the target substance well (solubilityIs high), chemically stable and soluteChemical reactionIt is most important not to.

Depending on the purposeBoiling pointIs low and easy to removeFlammability,toxicity,EnvironmentIncluding the impact on安全 性Is also emphasized.

Many solvents other than water are extremely flammable and produce highly toxic vapors.Further, in a chemical reaction, it is known that the progress of the reaction differs significantly depending on the type of solvent (Solvation effect).

Substances that are generally treated as solventsNormal temperature and pressureThen colorlessliquidMany of them have a peculiar odor.

Organic solvents for general useDry cleaning(Tetrachlorethylene),thinner(toluene,Terpin oil),ManicureRemoval liquidadhesive(acetone,Methyl acetate,Ethyl acetate), Stain removal (Hexane,Petroleum ether),Synthetic detergent(Orange oil),perfume(ethanol) OrChemical synthesis,ResinUsed for product processing.AlsoExtractionUsed for.

Indicator of characteristics

Polarity / solubility / miscibility

Solvents and solutes can be broadly divided into "highly polar solvents (highly polar solvents).Hydrophilic) ”And“ low polar solvents (Hydrophobic) ”, But there is no clear line because it is a matter of comparison.The polarity isPermittivity,Dipole momentEtc. are evaluated.As a rule of thumb, highly polar substances are easily soluble in high polar solvents, and low polar substances are easily soluble in low polar solvents.This is described as "melting into something similar."In particular,Inorganic salt(For exampleSalt) AndSugar(For exampleSucrose) And other highly polar substances are easily soluble in highly polar solvents such as water.oil,waxSubstances with low polarity such asHexaneEasily soluble in low polar solvents such as.Also, high and low polar solvents (eg water and hexane, etc.)VinegarSalad oil) Does not mix with each other, and even if it is shaken well, it often separates into two layers immediately.As a quantitative index of solubilitySolution parameterIs used.

Protic

The polar solvent isProtic and aprotic solventAprotic polar solventIt is classified as.A protic solvent is a solvent having a proton (hydrogen ion) donating property.Many proton solventsoxygenOrnitrogenRelatively high acidity bound to atomshydrogenhave.Also,oxygen-nitrogenSince it also has an unshared electron pair, it also has proton acceptability (Lewis basicity).Due to this property, the protic solvent is intermolecular between solvent molecules.Hydrogen bondThere are many things that form.Wed (H2O),ethanol (CH3CH2OH),Acetic acid (CH3C (= O) OH) is an example.As an aprotic polar solventAcetonitrile (CH3C≡N),acetone (CH3C (= O) CH3) And so on.Protic and aprotic solvents have the effect of stabilizing ions, soSN1 reactionIt is often used for reactions where ion generation such as is rate-determining.On the other hand, many aprotic polar solvents stabilize only protons and tend to increase the reactivity of anions.SN2 reactionEtc. are preferred.

Boiling point

For important properties of solventsBoiling pointHeat of vaporizationIs given, which determines the rate of evaporation.Diethyl ether,Methylene chlorideEtc., some low boiling point solvents are used as solvents that dry at room temperature in seconds.On the other hand, waterDimethyl sulfoxideIn order to dry a high boiling point solvent such as, conditions such as heating, depressurization, and air flow are required.

density

Many organic solvents are better than waterdensityIs small, and many of them float on the water.Exceptionally methylene chlorideChloroformな どhalogenSome of the system solvents and acetic acid have a higher specific gravity than water.

安全 性

Water is non-combustible and non-toxic[1]..Many solvents are dangerous and you need to pay attention to the high flammability of hydrocarbons and ethers, the explosive oxidation reactions of ethers, and the toxicity of benzene and the like.[2].

火災

For many solventsFlammabilityThere is.In generalvolatilityThe higher the value, the higher the flammability.However, there are also flame-retardant solvents such as methylene chloride and chloroform.In addition, most solvent vapors are heavier than air and tend to sink and stay in the lower part of the container.Therefore, solvent vapor may be present in empty drums and solvent cans.

Diethyl ether andTetrahydrofuran Ethers such as (THF)2-propanol,CumeneEtc. are highly explosive when exposed to oxygenPeroxideForm (Autoxidation).In particular, exposure to light accelerates the formation of peroxides.These peroxides are often concentrated to high boiling point fractions during distillation.Ethers in the dark BHT Although it is stored by adding a stabilizer such as, it should be noted that this does not completely stop the production of peracid.

Bunsen burnerInstead, use an electric flask heater for safety, and if the boiling point is 90 degrees or less, a steam bath is common.[3].

toxicity

Almost all organic solvents are toxic.Many organic solvents have an anesthetic effect and can cause rapid loss of consciousness during massive inhalation.Due to this property, it is for medical useAnesthetic,PainkillerIt was used as, but many of themNeurotoxicity,CarcinogenicIt is not currently used because it also has. (Diethyl etherIs still used as an anesthetic, but it is rarely used in developed countries due to its extremely flammability.)

CarcinogenicFrom the viewpoint of, in addition to chloroform, (gasolineAlso included)benzene,HMPAEtc. are considered to be or may be carcinogenic.

methanolIs produced by metabolismFormic acidfor,optic nerveDisability,blindnessIn addition, they may die.

Other,OrganThere are many things that cause troubles.liver,kidneyOrCerebrumSuch.

The toxicity and environmental load of organic solvents are often a problem.For this reason, chemical processes such as replacement of highly toxic solvents with relatively less toxic solvents (sometimes water) or reduction of the amount of solvent (sometimes solvent-free reaction) are being developed.They areGreen sustainable chemistryThis is the research content dealt with in.

There are more than 20 types of anti-chemical gloves, which means that not all are supported, and if inappropriate, they will pass through the gloves.[4]..Immediately wash with soap and water if exposed to harmful solvents (or chemicals, etc.)[4].

General precautions for use

  • Avoid exposure to solvent vapors and work environmentFume hoodOr improve ventilation.
  • Store in a closed container.
  • FlammabilitySolvents should not be opened near fire.
  • 爆 発And to avoid fireFlammabilityDo not flush the solvent to the floor.
  • Of solventvaporDo not inhale.
  • Do not apply solvent to the skin.Many solvents are more easily absorbed than the skin.

purification

A common solvent grade used in most extractions and chemical reactions is the "reagent grade", which is 97-99% pure and contains a small amount of water and volatile impurities.[2]..In some cases, a higher purity solvent is needed, which leads to the purchase of a higher purity solvent or purification of the solvent.[2].

To maintain chemical stability in the solventStabilizerMay be added.In addition, water and other impurities may be mixed.

Solvent purification is generally referred to as solvent purification.(I.e.distillationIs that[5].Molecular sheaveDrying with a desiccant such asdistillationPurification is often performed by operation.

Physical properties of typical solvents

Solvents were classified into non-polar solvents, polar aprotic solvents, and polar protic solvents.The polarities are expressed in terms of permittivity and are arranged in order of permittivity.Non-polar solvents with a higher density than water are shown in bold.

Physical properties of typical solvents
solventExpressive formulaBoiling point (℃)PermittivityDensity (g / mL)Sort
Hexane
(hexane)
692.00.655Non-polar
benzene
(benzene)
802.30.879Non-polar
toluene
(toluene)
1112.40.867Non-polar
Diethyl ether
(resin ether ether)
354.30.713Non-polar
Chloroform
(chloroform)
614.81.498 Non-polar
Ethyl acetate
(ethyl acetate)
776.00.894Non-polar
Methylene chloride
(methylene chloride)
409.11.326 Polar aprotic
Tetrahydrofuran
(tetrahydrofuran, THF)
667.50.886Polar aprotic
acetone
(acetone)
56210.786Polar aprotic
Acetonitrile
(acetonitrile)
82370.786Polar aprotic
N,N-Dimethylformamide
(N,N-dimethylformamide, DMF)
153380.944Polar aprotic
Dimethyl sulfoxide
(dimethyl sulfoxide, DMSO)
189471.092Polar aprotic
Acetic acid
(acetic acid)
1186.21.049Polar protic
1-Butanol
(1-butanol, n-butanol)
118180.810Polar protic
2-propanol
(2-propanol, Isopropyl alcohol)
82180.785Polar protic
1-propanol
(1-propanol, n-propanol)
97200.803Polar protic
ethanol
(ethanol)
79240.789Polar protic
methanol
(methanol)
65330.791Polar protic
Formic acid
(formic acid)
100581.21Polar protic
Wed
(water)
100800.998Polar protic

Source

References

  • J.Leonard, G.Procter, B.Lygo, "Experimental Techniques for Organic Chemical Reactions Useful in the Laboratory: From the Basics of Experiments to Reaction Operations under Inactive Gas," Maruzen Publishing Co., Ltd., 2012.ISBN 978-4-621-08433-5. Advanced practical organic chemistry, 2nd ed, 1998.
  • LF Fieser, KL Williamson "Fieser / Williamson Organic Chemistry Experiment" Maruzen, 2000, 8th edition.ISBN 4-621-04734-5. Organic experiments, 8th ed, 1998.

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