IAYDCSTRIa4LA S D ESGISEERIIYG C’HEJIISTRY
March, 19:30 Table I-Sulfur
F o u n d i n N a p h t h a s 2, 3, 4, a n d 6 a f t e r S t e a m Distillation f r o m Alkali a n d Copper S a l t s
MERClPTAN
SCLFUR ADDED
MERCAPTAN SULFUR IN DISTILLATE
REACES:T
2:
n-Butyl rec-Butyl
n-Am y l S . s ~ a T r i . 43:
Ethyl n-Propyl 1,opropyl
0 0792 0 0434 0 0537 0 0563 0 0882 0 0592
Hi0 CUSOI ( I O J I ) CUAC? CuSOa[l’l J f ) CUAC? HzO CuAc:
100
E N I h C AND
REDVC.
16g
%
0,083 0.030
0.078 0.043 0.034 0,036 0.028 0.0.54 0.009
98 54 43 a2 41 97 16
0.029 n 043 0.038 0.041 0.030
52 .5 1 64 69 51
0.04s 0.053 0.040 0.035 0 036 0.033 0.018 0.039 0.038
61 67 ;10
0.029
76 72
0.016
31 67 66
0 . 01’4
0.025
Tr
0.058
Tr S
S 0,038 0.040 S
CU.%C?
4: n-Hut)-l
s found x
70
Tr
CUAC?
MERCAPTAN SULFUR :OUND AFTER SWEET-
A . S . T. M. METHOD Sulfur less blank
70
“0 NAPHTHA
255
0.019 0.007 0.010 0,011 0 037 0.012 0.019
S?PiIms
0 0796
sei-Butyl
0 0462
~ec-Arn>-l
0 0562
X~PHT 6: H . ~ Ethyl n-Propyl
0 Oil5 0 0543
Isoprop>-l
0 0330
n-Hut>-l Isobutyl sec-ButyI n-Amyl
0 0 0 0
sec-.4myl
0 0470
0477 0528 0491 0501
CuSO:(lO .IJ) CuSOa KaOH Cuilc: CUSOIllO 31) CUSOIYaOH CUAC? CUSOi(l0 Jf) CuSO, XaOH CUAC?
0.017 0.020
CUSOi(l0 .If) CuSOa(2 5 M) CuSOa ( 5 0 M ) CuSOa (10 M ) CUACZ CuSOa ( 2 5 J J ) CUSOl ( 5 0 J f ) c u s o 4 (10 MI CUAC? c u s o 4 (10 J1) CUAC? cuso4 (10 .If) CuSOi ( 2 5 J J ) CUSO, ( 5 0 J I ) CUSO, 110 MI CuAcz c u s o a (10 .Lf)
0.004 0.011 0.005 Tr
S
0 004 0.004 S 0.006 0.0(17 S
-,,
S
0.0?3 0,020 0.013
S
0.005 S 0.017 0.024 0.014 0 009
S
0.017
0.017 0,019
0.020
0 019
change in the mercaptan sulfur due to the distillation. Thii mas te.ted with one sample, sec-octyl, and the difference before and after diatillation was 0.002 per cent, or within the range of experimental error. Whether this will be true for all is not known. (If possible a solution of the mercaptan in a different naphtha will be used to check this work.) On distillation from a copper acetate (same mol ratio as uqed in previous work) the didillate was sweet. It should be noted that the per cent of the added mercaptan sulfur recovered in the distillate from n- and sec-hexyl, n- and see-heptyl, and sec-octjl is the same as for the lower nier-
captans-that is, from 50 to 66 per cent. But with n-octgl the recovery dropped to 18 per cent, and with the n- and sec-nonyl the recovery is 10 per cent. The resultq from naphtha 7 show that the nonyl mercaptans are not so stable as the lower ones. That is, if the mercaptan group is attached to a carbon chain of nine carbons (or maybe eight), it is not so stable as if it were attached to a shorter carbon chain. Literature Cited (1) Borgstrom and Reid, IVD EVG. C H C M ,Anal E d , 1, 186 (1929) (2) Faragher, Morrell, and Monroe, IVDE v c C H E M ,19, 1281 (1927)
Maple Sirup Color Standards’’ R. T. Balch
I
S ORDER to promote uniformity in the grading of niaple 4rups. which is based principally on color, Bryan ( 1 ) published in 1910 a n arbitrary method for preparing
color standards from caramel dissolved in glycerol. The scale numbers ranged from Xo. 1, consisting of pure glycerol, to S o . 20, the full color of the standard caramel preparation. Commercial practice had already established the fact that high-quality maple sirup possesses an amber color, or one on the border line between amber and red, when Tiewed through the round pint bottle which is customarily usrd for packing this sirup. Maple sirup with color corresponding to that a t 1 Recehed January 23, 1930. Presented before the Division of Sugar Chemistry a t the 78th Meeting of the American Chemical Society, Minneapolis, I f i n n , September 9 to 13, 1929. Contribution No 68 from Carbohydrate Dirision, Bureau of Chemistry and Soils, r,S Department of Agriculture.
the border line betw-eeii amber and red wa. designated by Bryan as No. 7 . and sirups lighter or darker were graded according to the number to which their color corresponded on the arbitrary scale. The duplication of the Bryan color units depend. upon the reproduction of the exact color of the standard caramel preparation, since the remaining operations are mechanical and can be followed explicitly. I n formulating his directions for making the standard caramel, Bryan evidently believed that all granulated sugars beha\-e similarly when heated under the specified conditions and produce caramels of equal color intensity. Unfortunately this is not the caw, which fact was brought to the author’s attention when complaints were received to the effect that the standards made from cube sugar caramel were considered t o be entirely too light in color.
INDUSTRIAL A S D ENGIXEERING CHENIXTRY
256
Upon investigation the principal causes of this error were found to be twofold. The first, although not especially important in comparison to the other, but considered worthy of consideration, was the lack of adequate temperature control in Bryan's specifications. It was found that if the heating was conducted a t a temperature I " C. above or below the specified 212" C. for the entire period of 30 minutes, the color of the caramel from cube sugar varied *9 per cent from that produced a t exactly 212" C. The second cause for variation in the color of the standard caramel was due to the difference in behavior of granulated sugars when subjected to such a high temperature. Taking the caramel made from highly purified sucrose as a standard, the caramel from various samples of granulated sugar available on the market increased in color as much as 300 per cent.
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55
Vol. 22, KO.3
reliance was placed upon the judgment of one thoroughly familiar with the grading of maple sirups. The aid of C. H. Jones, of the Vermont Agricultural College, was enlisted to furnish a caramel solution which he considered to be a S o . 7-that is, one whose color was on the border line between amber and red when viewed through a pint bottle, the dimensions of which were believed to be the same as originally used by Bryan. This No. 7 caramel solution thus became our standard and starting point for the preparation of the remaining color units. After numerous trials with different lots of sugar, one was found that produced a caramel which, after being diluted for a I o . 7 according to Bryan's directions, corresponded in color to the Yo. 7 submitted by Jones. This caramel was therefore assumed to have the same color as that obtained originally by Bryan. This standard caramel preparation was then diluted with varying proportions of glycerol and the resulting solutions were examined spectrophotometrically and in a Pfund color grader, with the results recorded in Table I. .Voie-The Pfund color grader was designed particularly for the grading of honeys, hut owing to the similarity of the color standard (glass) t o the color of some sirups, it may be used for the grading of these as well a s for honey. T h e construction and mode of operation are described in U. S. Dept. Agr., Circ. 24.
$ t F/G /
P€E C€N7 ~ ~ ~ N ~ ~ / ~ ~ / 0 C€,L ~ ~ ~ 6 0 r n - /
With such variations in the quality of granulated sugar, it is impossible to make, with any degree of assurance, a caramel of standard color direct from sugar. These serious defects in the Bryan method, coupled with the fact that the caramel standards are not permanent, made it imperative that a study be made to find, if possible, (1) a trustworthy method of preparing color standards, particularly from caramel; and (2) standards having greater permanency than caramel solutions.
In comparing these solutions by use of the color analyzer it was not considered necessary to determine the complete transmission curves, but instead the per cent transmission was observed a t 560mp wave length, only. Table I-Spectrophotometric COMPOSITIOX m CARAM&LSOLU
