1314VARRENTRAPP REACTION
Varrentrapp reaction. Cleavage of oleic acid vegetable black. In general, any form of more
into palmitic and acetic acids by heating with molten or less pure carbon produced by incomplete com-
potassium hydroxide. The procedure has been ex- bustion or destructive distillation of vegetable mat-
tended to olefinic acids in general. ter, wood, vines, wine lees.
vasopressin. (-hypophamine; antidiuretic
vegetable dye. A colorant derived from a vege-
hormone). One of the hormones secreted by the table source, i.e., logwood, indigo, madder, etc.
posterior lobe of the pituitary gland. It causes in
blood pressure and an increase in water retention by
vegetable gum. See dextrin.
the kidney. Vasopressin is an octapeptide consisting
of eight amino acids.
vegetable oil. An oil extracted from the seeds,
Derivation: Synthetic, or from the posterior lobe of
fruit, or nuts of plants and generally considered to be
the pituitary of food animals.
a mixture of glycerides (e.g., cottonseed, linseed,
Grade: USP as an aqueous solution for injection.
corn, coconut, babassu, olive, tung, peanut, perilla,
Use: Medicine (antidiuretic).
oiticica, etc.). Many types are edible. Being plant-
derived products, vegetable oils are a form of bio-
vasopressin, 8-l-arginine-. See arginine va-
mass. Some are reported to be convertible to liquid
sopressin.
fuels by passing them over zeolite catalysts.
Use: Paints (as drying oils), shortenings, salad dress-
vat dye. A class of water-insoluble dyes that can
ings, margarine, soaps, rubber softeners, dietary
be easily reduced, i.e., vatted to a water-soluble and
supplements, pesticide carriers.
usually colorless leuco form in which they can readi-
ly impregnate fibers. Subsequent oxidation then
vegetable tanning. The tanning of leather by
produces the insoluble colored form that is remark-
plant extracts.
ably fast to washing, light, and chemicals. Examples
See tannic acid; tanning; wattle bark; quebracho.
are indigo (CI 73000) and Indanthrene Blue BFP (CI
69825). The reducing agents are usually an alkaline
vehicle. A term used in paint technology to indi-
solution of sodium hydrosulfite (Na
2
S
2
O
4
). Oxida-
cate the liquid portion of a paint, composed of drying
tion is by air, perborate, dichromate, etc.
oil or resin, solvent, and thinner, in which the solid
Use: For cotton, wool, and cellulose acetate.
components are dissolved or dispersed.
See paint.
vat printing assistant. A mixture of gums and
reducing and wetting agents used to carry the dye in
Venetian red. A high-grade ferric oxide pig-
printing fabrics with vat dyes. They assist in secur-
ment of a pure red hue. It is obtained either native as
ing penetration of the fabric and in converting the
a variety of hematite red or more often artificially by
dyes from a semileuco to a leuco state.
calcining copperas (ferrous sulfate) in the presence
of lime. The composition ranges from 15 to 40%
“Vatsol” [Cytec]. TM for a series of wetting
ferric oxide and from 60 to 80% calcium sulfate. The
agents made in several different grades and types:
40% ferric oxide is the “pure” grade and has a d 3.45.
OS, sodium isopropyl naphthalene sulfonic acid;
Grade: 20–40% ferric oxide.
OT, sodium dioctyl sulfosuccinate.
See iron oxide red.
vatting The process of solubilizing vat dyes in an
venturi. A type of flowmeter used for liquids or
aqueous solution of caustic soda and sodium hydro-
fine particulates. It is a tube like device having
sulfite.
broad, flaring ends and a narrow central portion, or
throat; this so constricts the passage of the fluid that
Vauquelin’s salt. (Pd(NH
3
)
4
)Cl
2
•PdCl
2
.A
its rate of flow increases while the pressure de-
compound obtained by treating palladium chloride
creases. The difference in pressure thus created is a
with ammonia.
measure of the flow. Venturis are used in scrubbers,
liquid and solid conveying systems, pipelines, and
aircraft instrument control, as well as in numerous
VC. Abbreviation for vinyl chloride or vinylidene
chemical process techniques such as hydrogenation,
chloride.
chlorination, and oxidation. The hydrogenation
technology involves hydrogen entrainment by rapid
vector. (1) In biochemistry, an animal (insect,
flow of a liquid catalyst through the venturi nozzle.
rodent, etc.) that carries or transports infectious mi-
croorganisms. Typical vectors are rats and mosqui-
toes. (2) A DNA molecule known to replicate auton-
veratraldehyde. (vertraldehyde; 3,4-dime-
omously in a host cell, to which a segment of DNA thoxybenzaldehyde).
may be spliced to allow its replication. The current CAS: 120-14-9. (CH
3
O)
2
C
6
H
3
CHO.
types are plasmids, cosmids, YAC’s or a temperate- Properties: Mp 42–45C, bp 281C, flash p 235F
phage DNA. (112C), mw 166.18.