| Identification | More | [Name]
Acetaldehyde | [CAS]
75-07-0 | [Synonyms]
ALDEHYDE C1
FORMALDE-FRESH
FORMALDE-FRESH SOLUTION
FORMALDE-FRESH SOLUTION, BUFFERED
FORMALDEHYDE
FORMALDEHYDE, BUFFERED
FORMALDEHYDE, CARSON-MILLON
FORMALDEHYDE DEVELOPING SOLUTION
FORMALDEHYDE SOLUTION
FORMALDEHYDI
FORMALIN
FORMALIN, CARSONS
FORMALIN, NEUTRAL
FORMALIN NEUTRAL BUFFER
FORMALIN, NEUTRAL BUFFERED
FORMALIN NEUTRAL SODIUM SALT
FORMIC ALDEHYDE
FORMOL
METHANAL
METHANONE | [EINECS(EC#)]
200-001-8 | [Molecular Formula]
C2H4O | [MDL Number]
MFCD00003274 | [Molecular Weight]
44.05 | [MOL File]
75-07-0.mol |
| Chemical Properties | Back Directory | [Description]
Acetaldehyde is a highly flammable, volatile colourless liquid. It has a characteristic, pungent,
and suffocating odour and is miscible in water. Acetaldehyde is ubiquitous in the
ambient environment. It is an intermediate product of higher plant respiration and formed
as a product of incomplete wood combustion in fireplaces and woodstoves, burning of
tobacco, vehicle exhaust fumes, coal refining, and waste processing. Exposures to acetaldehyde
occur during the production of acetic acid and various other industrial chemical
substances, for instance, manufacture of drugs, dyes, explosives, disinfectants, phenolic
and urea resins, rubber accelerators, and varnish. | [Appearance]
Acetaldehyde is a flammable, volatile, colorless liquid, or gas. It has a characteristic, penetrating, fruity odor. | [Melting point ]
-123 °C | [Boiling point ]
65-82 °C
| [density ]
1.09 g/mL at 25 °C(lit.)
| [vapor density ]
1.03 (vs air)
| [vapor pressure ]
52 mm Hg ( 37 °C)
| [FEMA ]
2003 | [refractive index ]
n20/D 1.377
| [Fp ]
133 °F
| [storage temp. ]
2-8°C
| [solubility ]
alcohols: soluble | [form ]
solution
| [pka]
13.57(at 25℃) | [color ]
White to off-white | [Specific Gravity]
0.823 (20/4℃) (?90% Soln.) | [Odor]
Pungent, fruity odor detectable at 0.0068 to 1000 ppm (mean = 0.067 ppm) | [PH]
5 (10g/l, H2O, 20℃) | [Stability:]
Stable, but air sensitive. Substances to be avoided include strong oxidizing agents, strong acids, reducing agents, alkalies, halogens, halogen oxides. Highly flammable. Vapour/air mixtures explosive over a very wide concentration range. May form peroxides in storage. | [explosive limit]
4-57%(V) | [Odor Threshold]
0.0015ppm | [Odor Type]
ethereal | [Water Solubility ]
> 500 g/L (20 ºC) | [Sensitive ]
Air Sensitive | [Usage]
Acetaldehyde is used as intermediate for syntheses of bulk chemicals, e.g. ethyl acetate, acetic acid, acetic anhydride, isooctylalcohol, pentaerythrite, pyridines, etc. For specific dyes, e.g. C.I. 46040 Basic Yellow 9. Product Data Sheet | [JECFA Number]
80 | [Merck ]
14,39 | [BRN ]
505984 | [Henry's Law Constant]
7.69 at 25 °C (Snider and Dawson, 1985:Benkelberg et al., 1995) | [Dielectric constant]
21.8（5℃） | [Exposure limits]
TLV-TWA 180 mg/m3 (100 ppm) (ACGIH),
360 mg/m3 (200 ppm) (NIOSH); STEL
270 mg/m3 (150 ppm); IDLH 10,000 ppm. | [Contact allergens]
Acetaldehyde, as its metabolite, is responsible for many
of the effects of ethanol, such as hepatic or neurological
toxicity. A case of contact allergy was reported in
the textile industry, where dimethoxane was used as a
biocide agent in textiles, and its degradation led to
acetaldehyde | [InChIKey]
IKHGUXGNUITLKF-UHFFFAOYSA-N | [LogP]
-0.16 | [CAS DataBase Reference]
75-07-0(CAS DataBase Reference) | [IARC]
2B (Vol. 36, Sup 7, 71) 1999, 1 (Vol. 100E) 2012 | [NIST Chemistry Reference]
Acetaldehyde(75-07-0) | [EPA Substance Registry System]
Acetaldehyde (75-07-0) |
| Hazard Information | Back Directory | [Chemical Properties]
Acetaldehyde is a highly fl
ammable, volatile, colorless liquid. It has a characteristic pun-
gent and suffocating odor, and is miscible in water. Acetaldehyde is ubiquitous in the
ambient environment. It is an intermediate product of higher plant respiration and formed
as a product of incomplete wood combustion in fi
replaces and woodstoves, burning of
tobacco, vehicle exhaust fumes, coal refi
ning, and waste processing. Exposures to acetal-
dehyde occur during the production of acetic acid and various other industrial chemical
substances. For instance, the manufacture of drugs, dyes, explosives, disinfectants, pheno-
lic and urea resins, rubber accelerators, and varnish. | [Chemical Properties]
Colourless clear liquid | [Definition]
ChEBI: The aldehyde formed from acetic acid by reduction of the carboxy group. It is the most abundant carcinogen in tobacco smoke. | [General Description]
A clear colorless liquid with a pungent choking odor. Flash point-36°F. Boiling point 69°F. Density 6.5 lb/gal. Vapors are heaver than air and irritate the mucous membranes and especially the eyes. Used to make other chemicals. | [Reactivity Profile]
ACETALDEHYDE(75-07-0) undergoes a vigorously exothermic condensation reaction in contact with strong acids, bases or traces of metals. Can react vigorously with oxidizing reagents such as dinitrogen pentaoxide, hydrogen peroxide, oxygen, silver nitrate, etc. Contamination often leads either to reaction with the contaminant or polymerization, both with the evolution of heat. Can react violently with acid anhydrides, alcohols, ketones, phenols, ammonia, hydrogen cyanide, hydrogen sulfide, halogens, phosphorus, isocyanates, concentrated sulfuric acid, and aliphatic amines. Reactions with cobalt chloride, mercury(II) chlorate or perchlorate form sensitive, explosive products [Sax, 9th ed., 1996, p. 5]. An oxygenation reaction of ACETALDEHYDE(75-07-0) in the presence of cobalt acetate at-20°C exploded violently when stirred. The event was ascribed to peroxyacetate formation [Phillips B. et al., J. Am. Chem. Soc., 1957, 79, p. 5982]. | [Air & Water Reactions]
Highly flammable. Easily oxidized by air to form unstable peroxides which may explode. Forms explosive mixture with air above 100°C (30-60% of the vapor in air) owing to formation of peroxyacetic acid [White, A. G. et al., J. Soc. Chem. Ind., 1950, 69, p. 206]. Soluble in water. | [Health Hazard]
Breathing vapors will be irritating and may cause nausea, vomiting, headache, and unconsciousness. Contact with eyes may cause burns and eye damage. Skin contact from clothing wet with the chemical causes burns or severe irritation. | [Health Hazard]
Exposures to acetaldehyde liquids and vapors for a prolonged period in work areas
cause irritation to the eyes, skin, upper respiratory passages, and bronchi. Continued
exposure is known to damage the corneal epithelium, dermatitis, photophobia, a for-
eign body sensation, and persistent lacrimation or discharge of tears. Acetaldehyde
causes bronchitis and a reduction in the number of pulmonary macrophages. The
severity of lung damage increases with the build up of fl
uid in the lungs (pulmo-
nary edema), and respiratory distress in the worker. Occupational workers exposed
to high concentrations of acetaldehyde suffer coughing, pulmonary edema, necrosis,
photophobia, a foreign body sensation, damage to the nasal mucosa and trachea, and
persistent lacrimation. | [Potential Exposure]
Acetaldehyde is used as a chemical intermediate and can be found in many processed foods; in crafts, arts, automotive, and home improvement products | [First aid]
If this chemical gets into the eyes remove any contact lenses at once and irrigate immediately for at least 30 minutes, occasionally lifting upper and lower lids. Seek medical attention immediately. If this chemical contacts the skin, quickly remove contaminated clothing. Immediately wash area with large amounts of soap and water. If a person breathes in large amounts of this chemical, move the exposed person to fresh air at once, and perform artificial respiration. Transfer promptly to medical facility. Medical observation is recommended for 24 to 48 hours after breathing overexposure, as pulmonary edema may be delayed. When this chemical has been swallowed, get medical attention. Give large quantities of water and induce vomiting. Do not make an unconscious person vomit. | [Shipping]
UN1088 Acetaldehyde, Hazard Class: 3; Labels: 3-Flammable liquid. | [Incompatibilities]
Reacts with air to form unstable peroxides which can explode. Contact with air causes acetaldehyde to chemically degrade to acetic acid. Strong oxidizers, acids, bases, alcohols, ammonia, amines, halogens, phenols, acid anhydrides, ketones, hydrogen cyanide, hydrogen sulfide. May dissolve rubber. Slightly corrosive to mild steel. May explode without warning when exposed to heat, dust, corrosives, or oxidizers. | [Waste Disposal]
Consult with environmental regulatory agencies for guidance on acceptable disposal practices. Generators of waste containing this contaminant (≥100 kg/mo) must conform with EPA regulations governing storage, transportation, treatment, and waste disposal. Incineration. | [Physical properties]
Colorless, mobile, fuming, volatile liquid or gas with a penetrating, pungent odor; fruity odor
when diluted. Odor threshold concentrations ranged from 1.5 ppbv (Nagata and Takeuchi, 1990) to
0.21 ppmv (Leonardos et al., 1969). Katz and Talbert (1930) reported an experimental detection
odor threshold concentration of 120 μg/m3 (67 ppbv). At low concentrations, acetaldehyde imparts
a pleasant, fruity, green apple or leafy green-like flavor (van Aardt et al., 2001). Twenty-five
panelists were randomly selected for testing milk products and water for determining flavor
thresholds. Flavor threshold concentrations determined by a geometric approach were 3,939 ppb
for nonfat milk (0.5% milk fat), 4,020 ppb for low-fat milk (2% milk fat), 4,040 ppb for whole
milk, 10,048 ppb for chocolate milk, and 167 ppb for spring water (van Aardt et al., 2001). | [Occurrence]
Reported.found.in.oak.and.tobacco.leaves;.in.the.fruital.aromas.of.pear,.apple,.raspberry,.strawberry.and.pineapple;.in.the.distillation.waters.of.Monarda punctata, orris,.cumin,.chenopodium;.in.the.essential.oils.of.Litsea cubeba, Magnolia grandiflora, Artemisia brevifolia, rosemary,.balm,.clary.sage,.Mentha arvensis, daffodil,.bitter.orange,.camphor,.angelica,.fennel,. mustard,.Scotch.blended.whiskey,.Japanese.whiskey,.rose.wine,.blackberry.brandy.and.rum.
| [Production Methods]
The main production method is the Hoeschst–Wacker twostage
process, in which acetaldehyde is generated by oxidizing
ethylene with aqueous palladium chloride over a copper
catalyst. Some acetaldehyde is also produced by oxidation
of ethanol. | [Aroma threshold values]
Detection:.0.7.to.200.ppb;.Recognition:.27.to.380.ppb | [Fire Hazard]
Acetaldehyde is a dangerous fire hazard (NFPA rating = 4) owing to its volatility and low autoignition temperature. Its vapor is explosive in the concentration range 4 to 66% in air and may be ignited by hot surfaces such as hot plates or light bulbs, or by static electricity discharges. The vapor is heavier than air and may travel a considerable distance to an ignition source and "flash back." Carbon dioxide or dry chemical extinguishers should be used to fight acetaldehyde fires.
| [Flammability and Explosibility]
Acetaldehyde is a dangerous fire hazard (NFPA rating = 4) owing to its volatility
and low autoignition temperature. Its vapor is explosive in the concentration range 4
to 66% in air and may be ignited by hot surfaces such as hot plates or light bulbs, or
by static electricity discharges. The vapor is heavier than air and may travel a
considerable distance to an ignition source and "flash back." Carbon dioxide or dry
chemical extinguishers should be used to fight acetaldehyde fires. | [Synthesis]
The.method.of.synthesis.is.dependent.on.the.price.of.feedstock.and.may.be.produced.by.a.number.of.methods:.(1).by. oxidation.of.ethyl.alcohol.with.potassium.dichromate.or.manganese.dioxide.in.the.presence.of.sulfuric.acid;.(2).by.addition.of.water. to.acetylene;.(3).by.formation.during.the.natural.alcoholic.fermentation.process..Recovery.is.effected.by.suitable.fractionation,.subsequent.preparation.of.the.acetaldehyde.ammonia.and.final.treatment.of.the.addition.compound.with.diluted.sulfuric.acid. | [Carcinogenicity]
Acetaldehyde is reasonably anticipated to be a human carcinogenbased on sufficient evidence of carcinogenicity from studies in experimental animals. | [Source]
Manufactured by oxidizing ethanol with sodium dichromate and sulfuric acid or from
acetylene, dilute sulfuric acid, and mercuric oxide catalyst.
Acetaldehyde was detected in diesel fuel at a concentration of 41,800 μg/g (Schauer et al.,
1999). Identified as an oxidative degradation product in the headspace of a used engine oil (10 to
30W) after 4,080 miles (Levermore et al., 2001).
Acetaldehyde occurs naturally in many plant species including Merrill flowers (Telosma
cordata), in which it was detected at a concentration of 1,026 ppm (Furukawa et al., 1993). In
addition, acetaldehyde was detected in witch hazel leaves (160 ppm), orange juice (3 to 15 ppm),
tangerines (0 to 2 ppm), pineapples (0.61–1.4 ppm), celery leaves, coffee seeds, cantaloupes,
soybeans, carrot roots, tomatoes, tobacco leaves, apples, peaches, black currant, fishwort,
peppermint, rice plants, and caraway (Duke, 1992). Acetaldehyde was detected in tobacco smoke
and marijuana at concentrations of 980 and 1,200 μg/cigarette, respectively (Hoffman et al., 1975).
The oil of alfalfa contained acetaldehyde at an approximate concentration of 0.2% (Kami, 1983).
Also detected among 139 volatile compounds identified in cantaloupe (Cucumis melo var.
reticulates cv. Sol Real) using an automated rapid headspace solid phase microextraction method
(Beaulieu and Grimm, 2001). In hand-squeezed grapefruit, acetaldehyde was detected at a
concentration of 6,150 μg/kg (Buettner and Schieberle, 2001).
Schauer et al. (2001) measured organic compound emission rates for volatile organic
compounds, gas-phase semi-volatile organic compounds, and particle phase organic compounds
from the residential (fireplace) combustion of pine, oak, and eucalyptus. The gas-phase emission
rates of acetaldehyde were 1,704 mg/kg of pine burned, 823 mg/kg of oak burned, and 1,021
mg/kg of eucalyptus burned.
Gas-phase tailpipe emission rates from California Phase II reformulated gasoline-powered
automobiles with and without catalytic converters were 3.94 and 301 mg/km, respectively
(Schauer et al., 2002).
Acetaldehyde is a degradation product of poly(ethylene terephthalate) during the melt
processing packaging for milk, water, and other beverage products. Occurs in many food products
such as yogurt and vinegar at concentrations up to 1,000 mg/L (van Aardt et al., 2001).
Acetaldehyde is a key ingredient in yogurt and is formed during milk fermentation by
microorganisms. Acetaldehyde is present in other fermented products such as cheese, butter, and
buttermilk (Ott et al., 2000). | [Environmental Fate]
Biological. Heukelekian and Rand (1955) reported a 5-d BOD value of 1.27 g/g that is 69.8% of
the ThOD value of 1.82 g/g.
Photolytic. Photooxidation of acetaldehyde in nitrogen oxide-free air using radiation between
2900 to 3500 ? yielded hydrogen peroxide, alkyl hydroperoxides, carbon monoxide, and lower
molecular weight aldehydes. In the presence of nitrogen oxides, photooxidation products include
ozone, hydrogen peroxide, and peroxyacyl nitrates (Kopczynski et al., 1974). Anticipated products
from the reaction of acetaldehyde with ozone or OH radicals in the atmosphere are formaldehyde
and carbon dioxide (Cupitt, 1980). Reacts with nitrogen dioxide forming peroxyacyl nitrates,
formaldehyde, and methyl nitrate (Altshuller, 1983). Irradiation in the presence of chlorine yielded peroxyacetic acid, carbon monoxide, and carbon dioxide (acetaldehyde into formic acid, methyl
nitrate, and peroxyacetal nitrate (Cox et al., 1980).
Chemical/Physical. Oxidation in air yields acetic acid (Windholz et al., 1983). In the presence
of sulfuric, hydrochloric, or phosphoric acids, polymerizes explosively forming trimeric
paraldehyde (Huntress and Mulliken, 1941; Patnaik, 1992). In an aqueous solution at 25 °C,
acetaldehyde is partially hydrated, i.e., 0.60 expressed as a mole fraction, forming a gem-diol (Bell
and McDougall, 1960). Acetaldehyde decomposes at temperatures greater than 400 °C, forming
carbon monoxide and methane (Patnaik, 1992). | [storage]
Acetaldehyde
should be used only in areas free of ignition sources, and quantities greater than 1
liter should be stored in tightly sealed metal containers in areas separate from
oxidizers. Acetaldehyde should always be stored under an inert atmosphere of
nitrogen or argon to prevent autoxidation. | [Purification Methods]
Acetaldehyde is usually purified by fractional distillation in a glass helices-packed column under dry N2, discarding the first portion of distillate. Or, it is shaken for 30minutes with NaHCO3, dried with CaSO4 and fractionally distilled at 760mm through a 70cm Vigreux column (p 11). The middle fraction is collected and further purified by standing for 2hours at 0o with a small amount of hydroquinone (free radical inhibitor), followed by distillation [Longfield & Walters J Am Chem Soc 77 810 1955]. [Beilstein 1 IV 3094.] | [Toxicity evaluation]
Industrial exposures to acetaldehyde are most likely to occur by
inhalation with potential for skin and eye contact. Accidental
ingestion is also possible. The main source of exposure to
acetaldehyde in humans is alcohol consumption and to a lesser
extent from air, vehicle exhaust, and from various industrial
wastes. Degradation of hydrocarbons, sewage, and solid biological
wastes produces acetaldehyde, as well as the open
burning and incineration of gas, fuel oil, and coal. |
| Safety Data | Back Directory | [Hazard Codes ]
T,Xn,F+,F | [Risk Statements ]
R23/24/25:Toxic by inhalation, in contact with skin and if swallowed .
R34:Causes burns.
R40:Limited evidence of a carcinogenic effect.
R43:May cause sensitization by skin contact.
R36/37:Irritating to eyes and respiratory system .
R12:Extremely Flammable.
R67:Vapors may cause drowsiness and dizziness.
R11:Highly Flammable.
R41:Risk of serious damage to eyes.
R22:Harmful if swallowed.
R10:Flammable. | [Safety Statements ]
S36/37:Wear suitable protective clothing and gloves .
S33:Take precautionary measures against static discharges .
S16:Keep away from sources of ignition-No smoking .
S26:In case of contact with eyes, rinse immediately with plenty of water and seek medical advice . | [RIDADR ]
UN 1198 3/PG 3
| [WGK Germany ]
2
| [RTECS ]
LP8925000
| [F ]
10 | [Autoignition Temperature]
185 °C | [TSCA ]
Yes | [HazardClass ]
3 | [PackingGroup ]
I | [HS Code ]
29121200 | [Safety Profile]
Confirmed carcinogen with experimental carcinogenic and tumorigenic data. Poison by intratracheal and intravenous routes. A human systemic irritant by inhalation. An experimental routes. A human systemic irritant by inhalation. An experimental teratogen. Other experimental reproductive effects. A skin and severe eye irritant. A narcotic. Human mutation data reported. A common air contaminant. Highly flammable liquid. Mixtures of 30-60% of the vapor in air ignite above 100℃. It can react violently with acid anhydrides, alcohols, ketones, phenols, NH3, HCN, H2S, halogens, P, isocyanates, strong alkalies, and amines. Reactions with cobalt chloride, mercury(Ⅱ) chlorate, or mercury(Ⅱ) perchlorate form violently in the presence of traces of metals or acids. Reaction with oxygen may lead to detonation. When heated to decomposition it emits acrid smoke and fumes. | [Hazardous Substances Data]
75-07-0(Hazardous Substances Data) | [IDLA]
2,000 ppm |
| Questions And Answer | Back Directory | [description]
Acetaldehyde, also called ethanal, is the simplest aldehyde (CH3CHO). Acetaldehyde is a colourless and volatile liquid made by the catalytic oxidation of ethanol, with a sharp and fruity odour.It is widely used industrially as a chemical intermediate.Acetaldehyde is also a metabolite of sugars and ethanol in humans,is found naturally in the environment, and is a product of biomass combustion.
Acetaldehyde is primarily used as an intermediate in the manufacture of a range of chemicals, perfumes, aniline dyes, plastics and synthetic rubber and in some fuel compounds. Acetaldehyde is an important reagent used in the manufacture of dyes, plastics, and many other organic chemicals.
In the presence of acids it forms the cyclic polymers paraldehyde (CH3CHO)3, and metaldehyde (CH3CHO)4. The former is used as a hypnotic, and the latter as a solid fuel for portable stoves and as a poison for snails and slugs.
Acetaldehyde is also used in the manufacture of disinfectants, drugs, perfumes, explosives, lacquers and varnishes, photographic chemicals, phenolic and urea resins, rubber accelerators and antioxidants, and room air deodourizers. It is also used as a synthetic flavouring substance, food preservative and as a fragrance.
figure 1 Acetaldehyde 2d structural formula | [As a flavor ingredient]
| CAS.No.: | 75-07-0 | FL.No.: | 5.001 | FEMA.No.: | 2003 | NAS.No.: | 2003 | | CoE.No.: | 89 | EINECS.No.: | 200-836-8 | JECFA.No.: | 80 | | |
CoE: Approved. Bev.: 23 ppm; Food: 20 ppm
FDA: 21 CFR 182.60, 582.60; 27 CFR 19.460, 21 et seq.
FDA (other): n/a
JECFA: ADI: Acceptable. No safety concern at current levels of intake when used as a flavoring agent (1997).
Reported uses (ppm): (FEMA, 1994)| Food Category | Usual | Max. | | Alcoholic.beverages | 470 | 470 | | Baked.goods | 30 | 280 | | Cheese | 0.0005 | 600 | | Chewing.gum | 0.78 | 9.2 | | Condiment,.relish | 0.5 | 5 | | Confection,.frosting | 83 | 2000 | | Fats,.oils | 0.1 | 4 | | Frozen.dairy | 94 | 150 | | Fruit.ices | 50 | 100 | | Gelatin,.pudding | 8.1 | 100 | | Gravies | 0.61 | 53 | | Hard.candy | 9.29 | 21.49 | | Imitation.dairy | 0.2 | 0.7 | | Jams,.jellies | 23 | 50 | | Meat.products | 1.67 | 5.53 | | Milk.products | 76 | 76 | | Nonalcoholic.beverages | 38 | 190 | | Reconstituted.vegetables | 0.0085 | 0.02 | | Snack.foods | 0.25 | 10 | | Soft.candy | 3 | 1000 | | Sweet.sauce | 13 | 230 |
Reported found in oak and tobacco leaves; in the fruital aromas of pear, apple, raspberry, strawberry and pineapple; in the distillation waters of Monarda punctata, orris, cumin, chenopodium; in the essential oils of Litsea cubeba, Magnolia grandiflora, Artemisia brevifolia, rosemary, balm, clary sage, Mentha arvensis, daffodil, bitter orange, camphor, angelica, fennel,mustard, Scotch blended whiskey, Japanese whiskey, rose wine, blackberry brandy and rum. | [Uses]
- Acetaldehyde can also be used as an odorant, and it found in nature in many foods such as ripe fruits, cheese and heated milk. acetaldehyde occurs naturally during fermentation, and low levels of acetaldehyde are to be found in certain foods. It is mainly used for preparation of citrus, apple, cream type essence, etc.
- Acetaldehyde is mostly used in acetic acid industry. Butanol and octanol are also the important derivatives of the acetaldehyde in the past. Nowadays, butanol and octanol are prepared by Propylene carbonyl synthesis method.
- Acetaldehyde is a very important raw material in the production of a large number of chemical products, for example paint binders in alkyd paints and plasticizers for plastics. Acetaldehyde is also used in the manufacture of construction materials, fire retardant paints and explosives, while its uses within the pharmaceutical industry include the manufacture of sedatives and tranquilisers, among other things. Acetaldehyde can also be used as a raw material in the manufacture of acetic acid, another platform chemical with many applications.
- Acetaldehyde is also used to produce pentaerythritol, peracetic acid, pyridine and its derivatives. Domestically produced acetaldehyde is mainly used as intermediate for the production of acetic acid. Only a small amount is used for the production of pentaerythritol, butanol, trichloroacetaldehyde, trimethylolpropane, etc.
- Acetaldehyde is primarily used to produce other chemicals, including acetal, Crotonaldehyde, acetic acid peroxide, hydroxyl acrylic nitrile, trichloroacetaldehyde, ethyl acetate, pentaerythritol, acetic anhydride, acetic acid, Glyoxal, phenyl acrolein, acetal, methyl ethylamine , diethylamine, α-Alanine, pyridine, α-methylpyridine, β-methylpyridine, γ-methylpyridine, etc.
| [Content analysis]
65 ml of 0.5 mol/L hydroxylamine hydrochloride and 50.0 ml of triethanolamine were added to a fixed pressure-heat resistant bottle with good sealing property. A slow nitrogen flow is fed into the bottle through a glass tube slightly above the liquid surface for 2 min to exhaust the air. About 600 mg of the sample, accurately weighed, was sealed in one ampoule bottle and put in the above mixture. Several short glass rods with the diameter of about 8 mm were added to the bottle. After covering the cork, the bottle was strongly shaken to break the ampoule. Then keep the reaction for 30 min at room temperature, shaking the bottle from time to time. Remove the cork after cooling if necessary. The whole process should be careful in order to avoid the loss of the product. The above system was then titrated by certain amount of 0.5 mol/L sulfuric acid to cyan end point. At the same time a blank titration was conducted. Each 0.5 mol/L sulfur acid was equivalent to 22.03 mg acetaldehyde (C2H4O). | [Toxicity]
GRAS(FEMA；FDA，§182．60，2000). LD501930mg/kg(rat，oral) | [Preparation]
Several production methods are used to produce ethanal.
(1) Direct oxidation of ethylene.
Ethylene and oxygen passed the catalysts containing palladium chloride, copper chloride, hydrochloric acid and water .Coarse acetaldehyde can be synthesyed by this one-Step direct oxidation process. Then, after a distillation process, the final product was obtained.
(2) Ethanol oxidation.
Under the 300-480 ℃, the air oxydehydrogenation process of ethanol vapor took place to produce acetaldehyde by using silver, copper or silver-copper alloy mesh as catalyst.
(3) Direct hydration of ethyne.
Under the effect of mercury catalyst or mercury free catalyst, the direct hydration reaction of acetylene and water was used to produce acetaldehyde. Due to the toxicity of mercury, this method has been gradually replaced by other methods.
(4) Ethanol dehydrogenation
Under the effect of copper catalyst with the addition of cobalt, chromium, zinc or other compounds, ethanol dehydrogenation took place to produce acetaldehyde.
(5) Saturated hydrocarbon oxidation.
Material Consumption Quota: one ton product of acetaldehyde costs 610kg ethyne(99%) by direct hydration of ethyne method; 1200kg ethanol (95%) by ethanol oxidation method; 710kg ethylene(99%) and 300m3 oxygen（99%） by ethylene oxidation method (one-step).
(6) Acetaldehyde can be prepared by ethylene oxidation.
Acetaldehyde can be prepared by gas phase hydrogenation of Ethanol.
Acetaldehyde can be prepared by simultaneous destructive distillation calcium acetate and calcium formate.
ethanal can be prepared by adduct reaction of acetylene and water. | [Hazardous Substances Data Bank (HSDB)]
Acetaldehyde has been classified by the International Agency for Research on Cancer (IARC) as Group 2B, possibly carcinogenic to humans, based on evidence in animals.Acetaldehyde is a respiratory tract carcinogen in experimental animals, especially of the nasal mucosa in rats and of the larynx in hamsters.
There is inadequate evidence for the carcinogenicity of acetaldehyde in humans. One small study of workers manufacturing several types of aldehydes found increased risk of bronchial tumours, but workers were exposed to many other chemicals in addition to acetaldehyde.Three other studies on the carcinogenicity of alcoholic beverages found that people who developed cancer after heavy alcohol use had genetic differences and higher concentrations of acetaldehyde in their blood compared to those who didn't develop cancer.Further study is required to establish a causal relationship.
Acetaldehyde can cause respiratory and eye irritation and in severe cases, lung edema. It also exacerbates the effects of alcohol and is a central nervous system depressant. |
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