Acetaldehyde

Acetaldehyde was first prepared by Scheele in 1774, by the action of manganese dioxide (MnO₂) and sulfuric acid (H₂SO₄) on ethyl alcohol (ethanol, CH₃CH₂OH).
The formation of acetaldehyde by the addition of water to acetylene was observed by Kutscherow in 1881.

The Acetaldehyde, with the CAS registry number 75-07-0 and EINECS registry number 200-001-8, is a kind of colourless clear liquid with the molecular formula of C₂H₄O. It is one of the most important aldehydes, occurring widely in nature and being produced on a large scale industrially. Acetaldehyde can be found naturally in coffee, bread, and ripe fruit, and it is produced by plants as part of their normal metabolism.

The physical properties of Acetaldehyde are as followings: (1)# of Rule of 5 Violations: 0; (2)ACD/BCF (pH 5.5): 1; (3)ACD/BCF (pH 7.4): 1; (4)ACD/KOC (pH 5.5): 20.875; (5)ACD/KOC (pH 7.4): 20.875; (6)#H bond acceptors: 1; (7)#H bond donors: 0; (8)#Freely Rotating Bonds: 0; (9)Polar Surface Area: 17.07 Å²; (10)Index of Refraction: 1.315; (11)Molar Refractivity: 11.501 cm³; (12)Molar Volume: 58.868 cm³; (13)Polarizability: 4.56×10^-24cm³; (14)Surface Tension: 17.618 dyne/cm; (15)Density: 0.748 g/cm³; (16)Enthalpy of Vaporization: 25.76 kJ/mol; (17)Boiling Point: 18.588 °C at 760 mmHg; (18)Vapour Pressure: 964.536 mmHg at 25°C.

Preparation: The main production method is the oxidation of ethylene via the Wacker process:
2CH₂=CH₂+O₂ → 2CH₃CHO

Uses: It is usually used as a precursor to acetic acid, but this application has declined because it can be made more efficiently from methanol by the Monsanto and Cativa processes. And in terms of condensation reactions, acetaldehyde is an important precursor to pyridine derivatives, pentaerythritol, and crotonaldehyde.

You should be cautious while dealing with this chemical. It is a kind of extremely flammable chemical which irritates to eyes and respiratory system. And there's limited evidence of a carcinogenic effect. Therefore, you had better take the following instructions: Keep away from sources of ignition - No smoking; Wear suitable protective clothing and gloves; Take precautionary measures against static discharges.

You can still convert the following datas into molecular structure:
(1)SMILES: CC=O
(2)InChI: InChI=1/C2H4O/c1-2-3/h2H,1H3
(3)InChIKey: IKHGUXGNUITLKF-UHFFFAOYAB

The toxicity data is as follows:

Organism	Test Type	Route	Reported Dose (Normalized Dose)	Effect	Source
frog	LDLo	intravenous	800mg/kg (800mg/kg)	BEHAVIORAL: GENERAL ANESTHETIC CARDIAC: OTHER CHANGES LUNGS, THORAX, OR RESPIRATION: OTHER CHANGES	Journal of Pharmacology and Experimental Therapeutics. Vol. 30, Pg. 429, 1927.
hamster	LC50	inhalation	17000ppm/4H (17000ppm)		Progress in Experimental Tumor Research. Vol. 24, Pg. 162, 1979.
hamster	LD50	intratracheal	96mg/kg (96mg/kg)		Progress in Experimental Tumor Research. Vol. 24, Pg. 162, 1979.
human	TCLo	inhalation	134ppm/30M (134ppm)	LUNGS, THORAX, OR RESPIRATION: OTHER CHANGES	JAMA, Journal of the American Medical Association. Vol. 165, Pg. 1908, 1957.
mammal (species unspecified)	LC50	inhalation	20100mg/m3 (20100mg/m3)	SENSE ORGANS AND SPECIAL SENSES: OTHER: EYE BEHAVIORAL: EXCITEMENT LUNGS, THORAX, OR RESPIRATION: DYSPNEA	Gigiena Truda i Professional'nye Zabolevaniya. Labor Hygiene and Occupational Diseases. Vol. 19(7), Pg. 54, 1975.
mouse	LC50	inhalation	23gm/m3/4H (23000mg/m3)		Current Toxicology. Vol. 1, Pg. 47, 1993.
mouse	LD50	intraperitoneal	500mg/kg (500mg/kg)		IARC Monographs on the Evaluation of Carcinogenic Risk of Chemicals to Man. Vol. 36, Pg. 101, 1985.
mouse	LD50	oral	900mg/kg (900mg/kg)		Gigiena Truda i Professional'nye Zabolevaniya. Labor Hygiene and Occupational Diseases. Vol. 25(11), Pg. 57, 1981.
mouse	LD50	subcutaneous	560mg/kg (560mg/kg)	BEHAVIORAL: GENERAL ANESTHETIC	Acta Pharmacologica et Toxicologica. Vol. 6, Pg. 299, 1950.
rabbit	LD50	skin	3540mg/kg (3540mg/kg)		Union Carbide Data Sheet. Vol. 12/13/1963,
rabbit	LDLo	intravenous	300mg/kg (300mg/kg)	BEHAVIORAL: CONVULSIONS OR EFFECT ON SEIZURE THRESHOLD LUNGS, THORAX, OR RESPIRATION: OTHER CHANGES	Journal of Pharmacology and Experimental Therapeutics. Vol. 30, Pg. 429, 1927.
rabbit	LDLo	subcutaneous	1200mg/kg (1200mg/kg)	BEHAVIORAL: CONVULSIONS OR EFFECT ON SEIZURE THRESHOLD LUNGS, THORAX, OR RESPIRATION: OTHER CHANGES	Journal of Pharmacology and Experimental Therapeutics. Vol. 30, Pg. 429, 1927.
rat	LC50	inhalation	13300ppm/4H (13300ppm)	BEHAVIORAL: EXCITEMENT LUNGS, THORAX, OR RESPIRATION: DYSPNEA	National Technical Information Service. Vol. OTS0534485,
rat	LD50	oral	661mg/kg (661mg/kg)	PERIPHERAL NERVE AND SENSATION: SPASTIC PARALYSIS WITH OR WITHOUT SENSORY CHANGE BEHAVIORAL: ALTERED SLEEP TIME (INCLUDING CHANGE IN RIGHTING REFLEX) LUNGS, THORAX, OR RESPIRATION: DYSPNEA	Agents and Actions, A Swiss Journal of Pharmacology. Vol. 4, Pg. 125, 1974.
rat	LD50	subcutaneous	640mg/kg (640mg/kg)	BEHAVIORAL: GENERAL ANESTHETIC	Acta Pharmacologica et Toxicologica. Vol. 6, Pg. 299, 1950.
rat	LDLo	intraperitoneal	500mg/kg (500mg/kg)	LUNGS, THORAX, OR RESPIRATION: DYSPNEA LUNGS, THORAX, OR RESPIRATION: OTHER CHANGES	Journal of Biological Chemistry. Vol. 152, Pg. 41, 1944.