Cinnamic aldehyde ((3-phenyl acrolein), C6H5ï¿½CH: CHï¿½CHO, an unsaturated aromatic aldehyde, is the chief constituent of cinnamon oil.
It may be obtained from storax by distillation with water, and synthetically by heating cinnamic acid with lime, by the action of aluminium chloride on a mixture of vinyl bromide and benzene, by removing the elements of hydrobromic acid from bromethylbenzene by means of alcoholic potash, or, best, by treating (-bromhydrocinnamic acid with soda, when it yields styrolene, carbon dioxide and hydrobromic acid.
The co-chlor compound results when, (3-phenyl-a-chlorlactic acid (from hypochlorous acid and cinnamic acid) is heated with water; it has a hyacinthine odour and yields phenylacetaldehyde when heated with water.
It contains about 20% of cinnamic acid in addition to 18 or even more of benzoic. (3) Palembang benzoin, an inferior variety, said to be obtained from Styrax benzoin in Sumatra, consists of greyish translucent resinous masses, containing small white opaque tears.
It does not appear to contain cinnamic acid.
CINNAMIC ACID, or Phenylacrylic Acid, C9H80 2 or C 6 H 5 CH: CH COOH, an acid found in the form of its benzyl ester in Peru and Tolu balsams, in storax and in some gumbenzoins.
The residual liquor is filtered and acidified with hydrochloric acid, when cinnamic acid is precipitated, C 6 H 5 CH0+CH 3 000Na= C 6 H 5 CH :CH 000Na-}-H 2 O.
Cinnamic acid crystallizes in needles or prisms, melting at 133° C.; on reduction it gives phenyl propionic acid, C 6 H 5 CH 2 CH 2 000H.
An isomer of cinnamic acid known as allo-cinnamic acid is also known.
For the oxy-cinnamic acids see Coumarin.
Resins when soft are known as oleo-resins, and when containing benzoic or cinnamic acid they are called balsams. Other resinous products are in their natural condition mixed with gum or mucilaginous substances and known as gum-resins.
Heated with anhydrous sodium acetate and acetic anhydride it gives cinnamic acid; with ethyl bromide and sodium it forms triphenyl-carbinol (C 6 H 5) 3 C OH; with dimethylaniline and anhydrous zinc chloride it forms leuco-malachite green C6H5CH[C6H4N(CH3)2]2; and with dimethylaniline and concentrated hydrochloric acid it gives dimethylaminobenzhydrol, C 6 H 5 CH(OH)C 6 H 4 N(CH 3) 2.
It occurs naturally in some resins, especially in gum benzoin (from Styrax benzoin), in dragon's blood, and as a benzyl ester in Peru and Tolu balsams. It can be prepared by the oxidation of toluene, benzyl alcohol, benzaldehyde and cinnamic acid; by the oxidation of benzene with manganese dioxide and concentrated sulphuric acid in the cold (L.
The resins when taken internally have much the same action as essential oils, which are closely allied chemically, while the benzoic and cinnamic acids in the balsams modify their actions very slightly.
They are polymers of cinnamic acid, into which they readily pass on distillation.
Riiber (Ber., 1902, 35, p. 2411; 1904, 37, P. 22 74), by oxidizing diphenyl-2.4-cyclo-butane-bismethylene malonic acid (fron cinnamic aldehyde and malonic acid in the presence of quinoline) with potassium permanganate.
It consists essentially of cinnamic aldehyde, and by the absorption of oxygen as it becomes old it darkens in colour and develops resinous compounds.